The Conversation

Eastern Australia’s wild weather has left coastal homes teetering on the brink of collapse, and has eroded beaches by up to 50m in parts of Sydney.

Now the attention turns to the clean-up. There are several legal issues for owners of damaged properties, particularly the question of if and how they can be compensated.

While the recent events cannot be attributed directly to climate change, they are certainly consistent with a warming world. Our institutions are ill-prepared for a potential increase in the frequency and severity of such events.

Insurance

Unfortunately, the success of insurance claims for damaged homes in Sydney will depend entirely on the terms of their policies. Some policies don’t cover erosion at all. Some policies only cover it if it occurs within a certain proximity of another insured event (for example, within 48 hours of a named storm event). Some policies also comprehensively exclude coverage for damage caused by actions of the sea.

What’s more, while insurance will cover damage to buildings, policies do not extend to cover damage to or loss of land. This is especially problematic in the case of damage caused by waves and storms, because erosion will often result in loss of land.

Under the traditional law doctrine, where land is lost to erosion, the Crown automatically gains title to the inundated land, without any obligation to pay compensation. So even if a home-owner is insured, they may find themselves with no land to rebuild on.

Legal proceedings

Another potential avenue for home-owners to pursue is proceedings against the relevant local government for negligent approval of development. The success of this type of proceeding is highly speculative – much will hinge upon when the development was approved and how much information on the coastal hazards was available at that time.

Where development was approved decades ago, it may be difficult to prove that a local government was negligent, because of the limited state of knowledge at the time. In the case of more recent development approvals, there may be an argument that a local government had a high level of knowledge of the risk and control of risk information. These are the type of factors a court will look at in assessing negligence.

On the flip side, a court may also find that a landholder knew of and accepted the risk. Negligence proceedings are by no means a guaranteed avenue for landholders to recoup their loss, but are an avenue that Collaroy landholders may be able to explore.

Disaster assistance

Where insurance is not available, and there are no strict legal rights against government, landholders may request disaster relief or assistance from government.

Despite the lack of any legal compulsion to do so, Australian governments have a long history of providing disaster relief to citizens when an extreme weather event causes property damage.

A recent Productivity Commission report estimated that, over the past decade, the federal government spent A$8 billion on post-disaster relief and recovery. State governments spent a further A$5.6 billion.

However, the availability and amount of a payment are not guaranteed. This may depend upon the number of other claims for assistance, and any other demands on government resources. A claim for disaster relief from government may be an option for Collaroy landholders, but many other home-owners are also affected by flooding due to the recent extreme weather – and so potentially there are many other requests for relief.

What should we learn from this event for the future?

While the pictures of houses being lost to the sea in Collaroy are confronting, these images may become more commonplace. The most recent scientific report from the Intergovernmental Panel on Climate Change suggests that, under a business-as-usual scenario, a global sea-level rise in the range of 0.53-0.97m by 2100 is likely.

Even if emissions are immediately reduced, a global sea-level rise of 0.28-0.60m by 2100 is still possible. This will be especially problematic in Australia, with an estimated 711,000 residential addresses located within 3km of the shore and less than 6m above sea level – not to mention the billions of dollars' worth of government infrastructure also located in these regions.

As sea levels rise, some properties may be permanently inundated. Others may be hit by storm surge impacts or erosion, which may be exacerbated by sea-level rise.

If these events continue to attract disaster relief, the financial burden will become too great for governments to bear. Furthermore, government disaster assistance does not solve the more intractable problem of land being lost to the sea.

The pictures from Collaroy should therefore prompt a discussion about how we, as a society, can deal with the potential impacts of coastal hazards on existing developments.

This is a challenging question to answer, but there is an opportunity to address it in a planned and co-ordinated fashion.

Justine Bell-James has previously received funding from the Australian Research Council and the National Climate Change Adaptation Research Facility.

The massive storms that have lashed Australia’s east coast over the past few days are not just a threat to lives and property, but also to our marine wildlife.

The increasing urbanisation of our coastlines, and proliferation of impervious surfaces, has meant that up to 80% of stormwater now runs rapidly into a dense underground network of drains.

These drains act like an expressway for pollution and debris in our cities, roads, gutters and gardens, sending a cocktail of contaminants directly into the aquatic ecosystems that lie at the end of the pipe.

Stormageddons

Earlier this year, Newcastle recorded its wettest January day since 1862. In 2015, New South Wales experienced a “once in a century” storm event.

These storms along Australia’s east coast originated mainly from naturally occurring low-pressure systems, which may become less frequent but more severe in the future. Worldwide extreme weather events are becoming more common, with about 18% of heavy precipitation events attributed to global warming.

Australia is not the only country receiving a drenching. Torrential rains have hit Texas twice this year, breaking records in May and unleashing two 100-year storms in less than a week. Louisiana and Mississippi have been placed on flood watch.

Across the Atlantic, Europe is also emerging from receding flood waters, with the River Seine in France at its highest levels since 1910 and southern Germany battered by thunderstorms, hail and flash flooding.

A pollution cocktail

Stormwater is a mixture of rain and any dissolved or solid pollutants carried along with it. The excess water flowing along streets and gutters picks up litter, oil and grease, and metals. Run-off from parks and gardens introduces fertilisers, pathogens, pesticides and soil.

In Sydney Harbour it has been estimated that more than two-thirds of the pollutants entering the waterway do so via stormwater drains, creating hotspots of pollution with concentrations 20 times higher than natural levels. More than 80% of the city’s catchment is covered by concrete, increasing the volumes of stormwater run-off.

When stormwater reaches a waterway it represents a significant ecological risk. Together with international colleagues, we have been investigating the impact of stormwater pollution on ecological communities large and small, including changes to the number of species, nutrient cycling, and the release of toxic compounds such as ammonia, nitrous oxide and hydrogen sulphide.

Mobile animals such as fish and crustaceans may be able to avoid pollution by temporarily moving. But other aquatic organisms such as seaweeds and animals that anchor to rocks are more vulnerable. If they don’t die from the exposure, they may accumulate significant concentrations of pollutants within their bodies.

In stagnant or poorly flushed waterways, the risk of exposure is greater as pollutants tend to linger in the water and become bound to sediments where they act as an ongoing stress.

A big question is what happens when ecosystems are exposed to many different pollutants. Some studies suggest the impacts will be greater than the sum of the individual pollutants.

Building better cities

The solution to stormwater run-off is to build better: to design and construct cities to protect waterways such as rivers, manage stormwater and also make them liveable for people too. This approach is known as water-sensitive urban design.

One example is the large underground water tanks that collect stormwater to be reused for irrigation at Sydney’s Barangaroo Reserve.

You can help at home too by retaining vegetation, installing rainwater tanks, clearing excess leaf litter and debris from guttering and driveways, and reducing the use of pesticides and fertilisers on gardens. Rainwater tanks have proven particularly successful at capturing all stormwater for reuse in toilet flushing and irrigation.

While we need to clean up our waterways, we also need to make sure that enough water and organic matter are flowing through our rivers and into the oceans. Getting the balance right will make for better cities and healthier oceans.

Katherine Dafforn receives funding from the Australian Research Council and Lendlease. She is affiliated with the Sydney Institute of Marine Science.

Emma Johnston receives funding from the Australian Research Council.

The flooding rains that have drenched eastern Australia have tragically left several people dead and several more missing in New South Wales and Tasmania. This is an all-too-common story – flooding rains are a major cause of deaths around the globe.

Since 1994, we have studied the trends and causes of deaths due to natural disasters. Recent research into flood fatalities in Australia from 1900 to 2015 is revealing some important insights.

Our research suggests many of these deaths are avoidable.

How people die in floods

Since 1900, 1,859 people in Australia have died in floods. That’s more than in bushfires and earthquakes, but less than heatwaves, which remain by far Australia’s most deadly natural peril (excluding pandemic diseases). Of these flood deaths, 178 have occurred since 2000.

The majority of deaths have been male (79%), although the proportion of females has increased since the 1960s. Children and adults younger than 29 make up the majority.

Overall, most deaths have occurred in New South Wales and Queensland, although a greater proportion of people die in the Northern Territory compared to the population. Most deaths happen in relative isolation, in flood events that claim either one or two lives.

Most people have died while attempting to cross a bridge, causeway, culvert or road, either on foot or in a vehicle. While most victims were capable of independent action and aware of the flood, the speed and depth of the water took them by surprise.

Of those who were attempting to reach a destination at the time of death, the greatest number were on their way home. Playing in flood water is also a significant cause of death, particularly for children and young adults. More women and children died in floods due to the decisions of others – for example, being a passenger in a vehicle.

Those on foot mostly perished during the daytime, whereas those in vehicles were more likely to die in the evening when visibility is poorer. The majority of fatalities happened within the local area close to where they lived.

Overall, flood deaths have been declining since the early 1960s. This is probably due to investments in flood mitigation and warning systems, and the work of emergency service organisations such as the State Emergency Services. Deaths associated with motor vehicles, however, are on the rise and those associated with four-wheel-drive vehicles have increased over the past 15 years. The large majority of drivers have been men.

Our research has shown that many people simply ignore warnings and road closure signs. In one case in 2015 in NSW, 84% of motorists were observed driving past road closure signs and entering flood waters. Most were men driving four-wheel-drive vehicles.

How can we prepare people?

Our unpublished survey has revealed that Australian emergency managers prefer improving roadside warning signage at causeways, flood warning systems and road design in flood-prone areas.

However, it is clear that current practices are failing and must be complemented with a strategy to inspire behavioural change in the community.

Education programs should be targeted at young males at risk of entering floodwater, and at females and children to raise their awareness so that they may be empowered to influence motorist behaviour.

It is too easy to underestimate the dangers associated with floods. Our vehicles, even four-wheel-drives, do not provide a safe means of crossing flooded roadways. The public must understand that flood waters need to be respected, and be ready to work with authorities to reduce risks posed by flooding to our towns and cities.

See here for the full research report.

Katharine Haynes receives funding from and is affiliated with the Bushfire and Natural Hazard Cooperative Research Centre.

Andrew Gissimg receives funding from the Bushfire and Natural Hazards Cooperative Research Centre.

Fire significantly added to our ability to change the world. Fire image from www.shutterstock.com

Over the past year, carbon dioxide (CO₂) levels in the atmosphere have risen faster than any period in the past 55 million years. That’s the finding of my study published in Global Change Biology.

From April 2015 to April 2016, CO₂ levels rose by 4.6 parts per million (ppm), reaching a level of 407.42ppm at Mauna Loa observatory, Hawaii. This rate has increased in the past 200 years and forms a unique spike, reflecting accelerating global warming reinforced by the recent El Niño.

CO₂ levels above 400ppm have not been observed in the Earth’s climate record since the Pliocene, 5.3-2.6 million years ago, when sea level was about 25 metres higher than at present.

While climate change has gained scientific attention in the past 50 years, and political action in the last 25, humans have been altering the atmosphere much longer than that.

About 7,000 years ago, the development of agriculture, burning and land clearing is believed to have led to a small rise in CO₂ in the atmosphere (around 20-25ppm). Methane also rose by a small amount from 5,000 years ago.

These small rises didn’t lead to increasing temperatures, because the overall temperature trend until the 18th century was cooling.

Humans have since increased CO₂ from 280ppm before the Industrial Revolution to over 400ppm. Together these global changes, driven by our use of energy, have led scientists to define a new geological age, the Anthropocene.

A new age

Although not yet officially recognised, the Anthropocene is widely considered to have begun in the 18th century with the release of greenhouse gases (CO₂, methane and nitrogen oxides), land clearing, chemical pollution and other human activities. These changes have accelerated since the 1950s.

Some think the Anthropocene began much earlier, linked to the first rise in greenhouse gases around 7,000 years ago. In evolutionary terms, it can be suggested the blueprint for anthropogenic global warming originated earlier still with the harnessing of fire.

The only natural parallel with the speed of climate changes over the last few decades is during mass extinctions, when the pace of change exceeds the ability of species to adapt. Mass extinctions in the past have been triggered by large-scale volcanic events or asteroid impacts.

This time it’s us causing the changes. The unique ability of an organism to trigger a mass extinction has a possible precedent in the history of Earth.

As US palaeontologist Peter Ward explains in Under Green Sky (2008), the Permian-Triassic mass extinction (about 251 million years ago) was, at least in part, caused by toxic gas released by purple-green algae from the oceans.

Fire and ice

What has made humans so effective at causing environmental change? There are two essential factors.

First, with the exception of humans, no species has ever been able to harness combustion in order to magnify its energy output. Humans mastered fire at least 1 million years ago, and possibly earlier.

Fire has allowed us to cook. Consequently, we were able to increase our protein consumption, hunt, protect ourselves from cold and wild animals, move into inhospitable climate, clear the land, smelt metals and construct machines.

Fire vastly increased the amount of energy available for people to use. Human respiration dissipates 2–10 calories per minute, a camp fire covering one square metre releases approximately three to four orders of magnitude more, and the output of a 1,000 megawatt-hour power plant expends yet higher orders of magnitude than the energy produced by human respiration.

Second, humans have been blessed by a relatively stable climate over the past 7,000 years, although mean global variations of less than 1℃ were sufficient to cause serious disruption to agriculture and a decline to collapse of civilisations.

Ice core evidence for the concentration of greenhouse gases and atmospheric temperatures during the last 740,000 years suggests highly unstable and often extreme climates during the ice ages (glacial) and during abrupt cooling phases (called “stadials”) during warmer (interglacial) periods, preventing the development of farming.

A stable climate developed around 7,000 years ago. This allowed large-scale Neolithic production of extra food and thereby the emergence of villages, towns and later cities. This opened the way for Homo sapiens to expand its population and trigger energy output by huge amounts.

Thus, despite their high intelligence, humans were largely restricted to hunting and gathering until they mastered fire and then until the climate stabilised enough to allow farming.

The future

Since the onset of the industrial age, humans have released more than 600 billion tonnes of carbon, pushing mean global temperatures up by around 1°C globally, or 1.5°C on the continents.

Allowing for the cooling effects of sulphur aerosols (which reflect sunlight), the rise in temperatures is closer to 2°C, a mean global temperature similar to the Pliocene (2.6 - 5.3 million years ago). More recently the rise of atmospheric CO₂ accelerated, to rates higher than 3ppm per year during 2012-2016.

While we know a lot about what may happen in a warming world, widely agreed projections of future temperatures do not include the possibility of abrupt climate tipping point events.

Following the peak of previous warm periods, the Atlantic Mid-Ocean Circulation (AMOC) has repeatedly collapsed due to the melting Greenland ice sheet and flow of cold meltwater into the ocean, triggering much colder temperatures, followed by further warming. Examples are the cold Younger Dryas (12,900-11,700 years ago) and the collapse of the North American ice sheet about 8,200 years ago.

A future AMOC collapse may be signified by a growing cold region southeast of Greenland in the North Atlantic. An AMOC collapse will trigger a sharp decline in temperatures in the North Atlantic region for a limited but unspecified period. With high atmospheric CO₂ levels, such a collapse would be followed by renewed warming.

Recent history inexorably links human civilisation to the Earth’s climate. Given its mastery of fire and nuclear fission, humanity would need to be both wise and in control if it is to avert the energy released from these sources from threatening nature and its own future.

This article is based on Climate, Fire and Human Evolution (2016) by Andrew Glikson.

Andrew Glikson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Australia’s east coast is recovering from a weekend of wild winds, waves and flooding, caused by a weather pattern known as an East Coast Low. Tragically, several people have died in flooding.

Parts of New South Wales have received more than 400mm of rain since Friday morning. Some places such as Canberra and Forster recorded their wettest June day on record. Waves have also caused severe coastal erosion and damaged property.

East Coast Lows are a type of low-pressure system or cyclone that occur on the Australian east coast. They are not uncommon, with about seven to eight lows a year causing widespread rainfall along the east coast, particularly during late autumn and winter. An East Coast Low in April last year caused similar damage.

But whenever they happen they raise the question: did climate change play a role?

Good news?

Climate models suggest that the cyclones that move through the global mid-latitudes, around 30° to 50°S, are moving south. This is contributing to long-term declines in winter rainfall in southwestern Australia and parts of southeast Australia.

These models also suggest that the atmospheric conditions that help East Coast Lows form could decline by between 25% and 40% by the end of the century.

In recent work, my colleagues and I looked even more closely at how climate change will affect individual East Coast Lows.

Our results also found East Coast Lows are expected to become less frequent during the cool months May-October, which is when they currently happen most often.

But there is no clear picture of what will happen during the warm season. Some models even suggest East Coast Lows may become more frequent in the warmer months.

And increases are most likely for lows right next to the east coast – just the ones that have the biggest impacts where people live.

This chart shows how the frequency of East Coast Lows could change by 2080 across May-October (left) and November-April (right). Red indicates fewer storms, while blue indicates more. Crosses show high agreement between climate models. What about the big ones?

The results in the studies I talked about above are for all low-pressure systems near the coast – about 22 per year, on average.

But it’s the really severe ones that people want to know about, like the current event, or the storm that grounded tanker Pasha Bulker in Newcastle in June 2007.

These storms are much rarer, which makes it harder to figure out what will happen in the future. Most of the models we looked at had no significant change projected in the intensity of the most severe East Coast Low each year.

Warming oceans provide more moisture, so intense rainfall is expected to increase by about 7% for each degree of global warming. East Coast Lows are no different – even during the winter, when East Coast Lows are expected to become less frequent, the frequency of East Coast Lows with heavy rain is likely to increase.

Finally, even though there may be fewer East Coast Lows, they are occurring in an environment with higher sea levels. This means that many more properties are vulnerable to storm surges and the impact of a given storm surge is that much worse.

Was it climate change?

While the frequency of cool-season East Coast Lows looks likely to decrease in the future, changes in the big ones are a lot less certain.

However, East Coast Lows are very variable in frequency and hard to predict. So far, there hasn’t been any clear trend in the last 50 years, although East Coast Lows may have been more frequent in the past.

As for extreme rainfall, studies have found little influence of climate change on Australian extreme rainfall so far. Climate variability, such as El Niño, currently plays a much larger role. This doesn’t mean climate change is having no effect; it just means it’s hard to tell what impact a warming world is having at this stage.

So did climate change cause this weekend’s storms? No: these events, including intense ones, often occur at this time of year.

But it is harder to rule out climate change having any influence at all. For instance, what is the impact of higher sea levels on storm surges? And how much have record-warm sea temperatures contributed to rainfall and storm intensity?

We know that these factors will become more important as the climate system warms further – so as the clean-up begins, we should keep an eye on the future.

Acacia Pepler receives funding from the Australian Research Council

Drink containers are the biggest contributors to rubbish in Australia. Litter image from www.shutterstock.com

Australians are serial wasters. For every 1,000 square metres (or about four tennis courts), Australians litter about 49 pieces of rubbish. The biggest culprits are drink containers, making up five of the top nine recorded pieces of litter by volume.

One way to reduce this litter is to refund people when they deposit drink containers for recycling through container deposit recycling (CDR) schemes. South Australia and the Northern Territory have CDR schemes. In May this year, New South Wales Premier Mike Baird announced a CDR scheme for his state, to begin in July 2017.

Under the scheme most drink containers over 150ml will be eligible for a 10c refund through state-wide depots and reverse vending machines. This has re-ignited an ongoing debate, largely driven by the drinks industry, which – as previously debated on The Conversation - vociferously opposes these schemes.

Refunds work

As part of the NSW process, we at BehaviourWorks Australia at Monash University recently reviewed research and data from 47 examples of CDR schemes or trials around the world. This work was commissioned by, but independent of, the NSW Environment Protection Authority.

The 47 CDR schemes recovered an average of 76% of drink containers. In the United States, beverage container recovery rates for aluminium, plastic and glass in the 11 CDR states are 84%, 48% and 65% respectively, compared with 39%, 20% and 25% in non-CDR states. The figures are similar in South Australia, one of the longest-running CDR schemes in the world: 84%, 74% and 85% for cans, plastic and glass compared with national averages of 63%, 36% and 36%.

Some CDR schemes donate the refund to charity, but people are more likely to return a container for a refund. And the greater the refund, the greater the return rates. Most schemes refund 5-10c; the 11 schemes in Canadian provinces include those with refund rates as high as 40c for glass containers over 1 litre in Saskatchewan.

CDR schemes reduce litter overall. Data from seven US states show 69–83% reductions in container waste and 30–47% reductions in overall waste.

Finally, government CDR schemes are sustainable. The 40 government schemes worldwide have operated for an average of 24.8 years and all except two are still going.

Industry opposition

CDR schemes work, so why do they face continued opposition from the drinks industry?

The first major argument against is cost – to the public, to producers, to jobs and to government via, for example, a reduction in alcohol tax revenues due to reduced sales.

We found little published evidence to support these claims. The few studies identified were either funded by the beverage industry or theoretical arguments without any empirical data. Manufacturers and consumers will share the costs of the NSW CDR scheme, with consumers paying an estimated A$30 into the scheme annually should they not redeem any deposits.

The most robust cost data, the Packaging Impacts Decision Regulation Impact Statement, was prepared for the Australian government in 2014. This found that CDR schemes were more expensive than other packaging recovery and recycling options, but reduced litter the most.

The question of whether the cost is worth the return is an important aspect of the debate, and one that should be considered not just by the beverage industry but by all stakeholders, including the wider community.

Can industry do the job?

The second argument against government CDR schemes is that industry can recycle containers itself. Examples to support this argument are sparse and unconvincing.

In 2010, Coca-Cola launched a reverse vending machine scheme in Dallas Fort-Worth, Texas, with a target of 3 million beverage containers recycled per month. The scheme folded in October 2014, having achieved roughly a quarter of this target.

PepsiCo’s ongoing Dream Machine initiative of college-based reverse vending machines commenced in April 2010 with the goal of increasing the US beverage container recycling rate from 34% to 50% by 2018. It reported collection of over 93 million containers by 2012. Although an impressive-sounding yield, achieving the target of a 50% recycling rate would require multiplying this effort 400-fold.

These examples illustrate that industry-based CDR schemes appear either unsustainable or lack realistic targets.

Replacing recycling?

Thirdly, it is argued that CDR schemes will cannibalise existing kerbside recycling programs. The evidence suggests that the effect, if any, is the reverse – marginal increases in kerbside recycling have been noted following introduction of CDR legislation.

This may be linked to the “spillover effect” where people are more likely to do one thing if they are already doing something similar. The data from CDR schemes suggest that people may be more inclined to use kerbside recycling simply by buying a drink with a container deposit, not just getting the refund. As an example, South Australia’s overall recycling rate in 2008–2009 was 67%, against a national average of 51%.

Behavioural research also tells us that convenience is a major factor in CDR schemes, particularly how close collections are to people’s homes. Vending machines are perceived as convenient but data on whether they work are mixed.

There is also robust evidence that clean environments are likely to remain cleaner (than otherwise would be the case) and that littered environments are likely to attract more litter.

This underlines the findings from research that CDR schemes not only increase beverage container recycling, but reduce litter. Ongoing CDR debate should be informed by research evidence and involve all stakeholders in this multifaceted issue.

BehaviourWorks Australia received funding for this commissioned review from the NSW Environment Protection Authority. This funding was paid to Monash University, not any of the authors personally.

BehaviourWorks Australia received funding for this commissioned review from the NSW Environment Protection Authority. This funding was paid to Monash University, not any of the authors personally.

BehaviourWorks Australia received funding for this commissioned review from the NSW Environment Protection Authority. This funding was paid to Monash University, not any of the authors personally.

AAP/Paul Miller

With an unprecedented storm flooding large population centres on Australia’s east coast over the weekend, you would be forgiven for thinking politicians on the campaign trail might pause to reflect on climate change.

On the other side of the world, France and much of west and northern Europe are also experiencing extensive floods. They are unprecedented in the speed at which they have deluged cities and communities.

Climate change did not overdetermine these floods in Australia and Europe. But, it has super-charged their intensity and speed in a way that would make them rare in the past.

The weather patterns are complex, but the climate change part of the science is less so. Every 1℃ increase in global average temperature means the atmosphere can hold 7% more water vapour. This means that when moist air condenses into rainfall, it is capable of coming down for much longer and in much greater volume than it did in pre-industrial times.

Climate change is not about some kind of linear increase in temperature. It is about an increase in energy in the climate system that produces extremes – in drought, storms, wind, heatwaves and floods. Floods are just one of the expressions of the violence of the excess energy.

Analysis from the Potsdam Institute for Climate Impact Research, published last year and reported in the New York Times, showed record-breaking rainfall has increased 12% from 1980 to 2010 compared to the previous 80 years. In Europe, the increase was 31%. This is because the northern hemisphere temperature anomalies are so much greater than the south.

In France, the floods are getting attention as they are affecting globally recognised public treasures such as artwork at the Louvre and Musee d’Orsay. Paris hasn’t experienced a flood of this magnitude in more than 30 years, and certainly not one that has accumulated at the speed of this one.

This has moved French President Francois Hollande to link the flood to climate change, only six months after the climate summit held in Paris last December.

But, in Australia, at the midway point of an election campaign, the leaders of the major parties failed to mention our floods. Malcolm Turnbull aired the hang-up he shares with Bill Shorten about avoiding a hung parliament to shore up their own political power.

Ironically, a hung parliament might lead to power-sharing with the one party likely to drive effective action on climate – the Greens.

The Great Barrier Reef visits Australian voters

At a time when some are “reef-stricken” about the pending loss of coral at one of the world’s greatest natural wonders, many are oblivious to the seriousness of the bleaching process. While Environment Minister Greg Hunt would like to take credit for management of the Great Barrier Reef, the greatest palpable threat to the reef is warming sea-surface temperatures.

Just days after it was revealed the Australian government had lobbied for the removal of an entire chapter on the reef from a UN report, Hunt applauded his own management of the reef.

With the current floods, we are now seeing the hangover from the record sea surface temperatures that emerged in the last six months. This has devastated 93% of the reef.

But the leaders appear to be afraid of any kind of contest, let alone one on climate change. Last week’s highly scripted leaders’ debate largely dodged climate change, despite persistent questioning from Financial Review journalist Laura Tingle.

There is a growing indication that voters are taking extreme weather into their deliberations around climate policy. Even though mainstream media is notoriously bad at linking extreme weather to climate change, which is taboo for many Coalition MP’s, voters make this link themselves simply by experiencing it on an ever-more regular basis.

Even Deputy Prime Minister Barnaby Joyce, one of the eight-member kill-the-carbon-tax group that met every week in Cory Bernardi’s office, is having second thoughts. A feature article in the Sydney Morning Herald had him questioning his faith in Coalition groupthink.

After visiting his parents parched landholding in Rutherglen, Joyce declared:

I start to wonder whether climate change might really be happening.

This phenomena is an example of what 350.org founder Bill McKibben said at the end of what he regarded as a failed climate summit in Paris. Without an effective agreement, there is only one negotiation that remains: with physics itself. And physics actually holds all the cards.

As voters confront the physics or – put another way – extreme weather visits upon us, climate change becomes depoliticised.

But, in ignoring the physics, the cowardly climate stance that the major party leaders have taken is likely to backfire. Both leaders set out from the position that climate change has become so politicised that swinging voters are more likely to change their voter intention on other issues such as “jobs and growth”, education and hospitals.

A telling statistic here comes from three weeks of data collected by the ABC’s Vote Compass. 63% of the 250,000 respondents now want to see a price on carbon in Australia, compared to 50% in 2013.

But, more significantly, the shift was most marked in Coalition voters. There is a 13% increase in those wanting a price on carbon (41% agree, 22% are neutral).

These figures have prompted former Liberal leader John Hewson to challenge the idea that the Coalition’s 2013 campaign to “axe the tax” won it the last election.

As the Mona Lisa makes its way to higher ground, and Australians are asked to stay indoors across four states, the reality of climate change continues to assert itself. While they may be in denial, politicians cannot dismiss climate change as an issue that comes and goes. It is here to stay for today’s voters and for every election to come.

Our EcoCheck series takes the pulse of some of Australia’s most important ecosystems to find out if they’re in good health or on the wane.

Western Australia’s iconic Banksia woodlands are the predominant ecosystem along the Swan Coastal Plain – part of the southwest Australian global biodiversity hotspot, a region internationally recognised for its huge diversity of flowers and other wildlife.

The Swan Coastal Plain, home to Banksia woodlands, and most of Western Australia’s humans. Hesperian/IBRA/Wikimedia Commons, CC BY-SA

With more than 2,100 plant species, 2,250 invertebrates and 256 vertebrates, these woodlands are truly unique. However, they share this coastal plain with Perth, one of the fastest-growing cities in the world. Staggeringly, the Perth-Mandurah urban corridor is larger than the official city boundaries of Los Angeles and Tokyo put together (although, in fairness, those cities' satellite regions have their share of urban sprawl too).

Greater Perth’s population has crept past 2 million, across an area that extends 123km along the coast and about 30km inland. By 2050, Perth’s population is projected to reach 3.5 million and to stretch more than 240km along the coast.

While there have been some efforts to look at how to contain the sprawl, new land is still being released for development.

Banksia woodlands are under threat

Banksia woodlands are disappearing at an alarming rate. The woodlands have essentially been lost from the central part of their range (the Perth metropolitan area), leaving behind a scattering of suburban remnants.

These remnants, which include the 267 hectares of bushland in Perth’s iconic Kings Park, are under stress from other threats too, including inappropriate fire regimes, invasive species and climate change. Over the past 60 years these factors have contributed to a loss of many mature Banksia trees.

Around 80% of the woodland plants depend on pollinators such as native insects, birds, and mammals like Western Australia’s unique Honey Possum. Therefore, it is critical to maintain a connected network of woodland remnants across the metropolitan region, so that these pollinators can move freely throughout the habitat. It is not enough simply to conserve isolated patches such as Kings Park.

The federal government is assessing whether to add these Banksia woodlands to its list of threatened ecological communities, which would pave the way for a co-ordinated program to help protect them.

This is timely, coming in the face of the WA government’s proposed Perth-Peel Green Growth Plan, which will result in the loss of a further 9,800ha of Banksia woodlands (about 13,611 soccer fields, or 24.5 times the total area of Kings Park) and a further decline in numbers of the endangered Carnaby’s Black Cockatoo.

A way forward?

The good news is that Banksia woodlands can be successfully restored, and indeed some small pockets have been already. Roughly 70% of species returned to a restored site previously used for collecting construction sand.

However, Banksia trees take decades to reach maturity, making restoration a slow process, not to mention an expensive one. The cost of restoring cleared land has previously been estimated at A$30,000 per hectare, and Banksia attenuata seed alone can cost A$220 per 1,000 seeds.

The Perth-Peel plan would include the creation of 170,000ha of woodland reserves as mitigation for development. However, this is not a net gain, as these areas already exist. Some revegetation is planned, but as we have seen above, this is expensive and not always successful.

Perth has one of the lowest population densities in the world, with an average of just ten homes per hectare. Infill development has been proposed as an antidote to urban sprawl, but care needs to be taken that this infill does not fragment urban woodlands still further.

For a city of 2 million, Perth is still pretty flat. Bev Sykes/Wikimedia Commons, CC BY Smarter planning

We cannot undo past developments. However, we should learn from them and reduce our future impact. This means using the best available restoration science and translating it into smarter planning and development to preserve existing woodlands on the Swan Coastal Plain, rather than trying to fix or offset the losses.

We need to know how changes in climate, particularly rainfall, will impact on Banksia woodlands. But, above all, the issue needs to be communicated beyond the scientific community. The public should be aware of the environmental and social benefits of conserving and restoring Banksia woodlands, from cooling our city streets to preserving WA’s beloved black cockatoos.

Finding the balance between urban sprawl and healthy woodlands will require collaboration between ecologists, policy scientists, urban planners, developers and local councils. Only with smarter development planning will we secure the successful management and future of the Banksia woodlands that once covered the Swan Coastal Plain.

Are you a researcher who studies an iconic Australian ecosystem and would like to give it an EcoCheck? Get in touch.

Alison Ritchie receives research funding from Urban Resources. She is Honorary Secretary of the Society for Ecological Restoration Australasia (SERA).

Elizabeth Sinclair receives funding from Australian Research Council.

Jason Stevens receives funding from the Western Australian State Government, Australian Research Council.

Lucy Commander receives funding from Sinosteel Midwest Corporation. She is a board member of the Society for Ecological Restoration Australasia (SERA).

Robert Davis has previously received funding from Perth Region NRM and the Department of Parks and Wildlife to study Banksia woodland birds. He is an immediate past director of Birdlife Australia.

William Fowler does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Trade Minister Steven Ciobo, speaking on Q&A. Q&A

The Conversation is fact-checking claims made on Q&A, broadcast Mondays on the ABC at 9.35pm. Thank you to everyone who sent us quotes for checking via Twitter using hashtags #FactCheck and #QandA, on Facebook or by email.

Excerpt from Q&A, May 30, 2016.

Global demand for coal is still going through the roof. – Trade Minister Steven Ciobo, speaking on Q&A, May 30, 2016.

Trade Minister Steve Ciobo told the Q&A audience that global demand for coal is still going through the roof. (Watch from 2:38 in the clip above.) Is that correct?

Checking the source

When asked for a source to support his statement, a spokesman for Steven Ciobo said the minister had addressed the issue in a tweet sent the day after the Q&A program aired.

Ciobo’s tweet refers to the International Energy Agency’s (IEA) 2014 Medium-Term Coal Market Report.

This report said:

In 2013, coal added more primary energy than any other fuel and was the fastest-growing fossil fuel. 2013 coal demand grew 2.4% on a tonnage basis, more than oil and gas, enhancing its position as the second-largest primary energy source and closing the gap with oil.

The report, however, goes on to note that coal prices in 2014 were low due to significant global oversupply, saying that:

In 2014, coal oversupply persists and very low coal prices continued to dominate. For a few years, the focus of coal producers was to expand production. New capacity was constantly added and demand led by China consumed every additional tonne. However, since 2011, oversupply and low prices have dominated.

Fast-forward one year, and the IEA’s 2015 Medium-Term Coal Market Report says that global coal demand growth has “halted”:

For the first time since the 1990s, global coal demand growth halted in 2014. This was the result of a combination of some structural and temporal factors, mostly in China, where half of global coal is used… Given the economic rebalancing in China and ongoing structural decline in OECD countries, even with the continuation of growth in India and ASEAN countries, a downward trend in global coal consumption in 2015 is likely.

Declining coal consumption in China is reducing global demand

The decrease in coal consumption in China was effectively an overhang from the global financial crisis (GFC).

During the GFC, China sought to avoid economic decline by a significant domestic stimulus program.

The stimulus program bolstered investment in construction and manufacturing in the years following, but is now petering out. Reports point to a worsening situation in 2015, as coal imports declined sharply from 2014.

Further evidence of declining global coal demand is the fall in coal prices out of Newcastle.

A good indication of coal demand is the share prices for coal miners. In the US and in Australia, coal mining companies’ share prices are not showing evidence of high expectations of growth in demand.

Author provided. Can India fill the gap?

The IEA’s 2015 Medium-Term Coal Market Report noted that India is the only major economy with strong coal growth.

However, the report found that:

India is not the new China. As forecast in former editions of this report, India will become the second-largest coal consumer in the world, bypassing the United States, and the largest importer of thermal coal… [However], growth in India and ASEAN countries will not compensate for the new trajectory of Chinese coal demand.

The situation in India is fluid. Prime Minister Narendra Modi is reported to be a champion of solar energy and the country is pursuing significant investment in solar (as well as coal).

India’s Energy Minister Piyush Goyal is committed to eliminate costly coal imports of thermal coal for use in electricity generation.

IEA modelling gives clues about future global coal demand

The IEA makes projections into the future in a report called the World Energy Outlook.

Last year’s projections provided three scenarios: a current policies scenario, a new policies scenario (also known as the medium scenario) and a 450 scenario.

The 450 scenario models energy demand based on policies required to cap the concentration of greenhouse gases in the atmosphere to 450 ppm (parts per million). That’s the level needed to stand a chance of keeping global warming to 2°C.

The IEA’s new policies (or “medium”) scenario and subsequent modelling of global leaders' commitments to carbon reduction assume that “climate ambition is not raised progressively” and warming will most likely be in the 2.7 to 3.5 degree range.

Author provided.

Global leaders reaffirmed at the Paris Climate Conference the goal of limiting global temperature increase well below 2°C.

On that basis, the IEA’s 450 scenario may give us a clue about future energy demand in a world committed to avoiding dangerous climate change.

The IEA’s 450 scenario shows a very significant decline in consumption of coal in the decades ahead. That also calls into question the minister’s claim that coal demand is still going through the roof.

Verdict

Steven Ciobo’s statement that global coal demand is “going through the roof” is inaccurate.

Review

The FactCheck is correct, but the author could place more emphasis on the central scenario from the International Energy Agency, rather than its 450 scenario.

The latest predictions for the future of coal demand from the International Energy Agency have highlighted that the massive growth in demand for coal over the past 15 years will not continue, and the fuel faces more uncertain times.

Consumption of coal across OECD countries is predicted to fall 40% by 2040. Yet the central scenario of the IEA still has coal meeting 10% of future increases in energy needs to 2040.

This is driven in particular by Southeast Asia, where primary energy demand for coal is predicted to triple between 2020 and 2040.

This means that the most likely IEA scenario is that global consumption of coal will continue to increase but at a much slower rate than before, noting that there is still uncertainty about how China’s and India’s consumption may change over time. – John Rolfe

Have you ever seen a “fact” worth checking? The Conversation’s FactCheck asks academic experts to test claims and see how true they are. We then ask a second academic to review an anonymous copy of the article. You can request a check at checkit@theconversation.edu.au. Please include the statement you would like us to check, the date it was made, and a link if possible.

John Rolfe receives funding from the Australian Coal Association Research Program (ACARP) for a research project on mine closures and land use change back to agriculture.

Lynette Molyneaux does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

You know that feeling when you open the fridge and are met with something “on the nose”. We all know what food waste looks and smells like.

But food waste stinks in more ways than one. It is expensive, costing the average household over A$2,200 a year, and it undermines the resilience and sustainability of our food supply.

A new report from our Foodprint Melbourne Project has estimated the amount of food that is wasted in feeding Melbourne. We found that feeding Melbourne generates more than 900,000 tonnes of edible food waste every year, or over 200 kg per person.

This is enough to feed more than 2 million people for a year*.

Food waste occurs at different stages for each food type. Foodprint Melbourne Undermining sustainability

Growing this wasted food uses 180 gigalitres of water each year, or 113 litres per person per day. This is equivalent to running your shower for an extra 10 minutes a day.

This wasted food also uses around 3.6 million hectares of land – around 41 ha per person, or more than 20 times the area of the Melbourne Cricket Ground.

And this wasted food is responsible for around 2.5 million tonnes of greenhouse gas emissions, 60% of which is generated by food waste rotting in landfill, and the rest in producing the wasted food.

This uneaten food is not only a source of unnecessary greenhouse gas emissions. It represents a waste of natural resources that are in increasingly limited supply.

Australia is a water-scarce region that is likely to become drier due to climate change, while only 6% of Australia’s land is suitable for growing crops.

With the associated waste of natural resources, high levels of food waste add to the challenge of producing sufficient food to feed a growing population.

Reducing food waste

There are many ways to reduce food waste at home. These include making meal plans, sharing leftover food with friends or neighbours, checking the fridge before going shopping and storing food correctly.

The Cloud-Freezer app can help you to keep track of what’s in your freezer and fridge. Worm farms, bokashi bins and other forms of composting are also great ways to divert food waste from landfill.

While we can all take steps to reduce food waste at home, we need to look at the bigger picture. Our research shows that more than 60% of food waste is generated before food reaches your fridge or freezer.

Strict standards defining the shape, size and colour of fresh fruit and vegetables in supermarkets can mean that a significant proportion of a crop never leaves the farm.

Low prices for second-grade produce can make it financially unviable for farmers to pick, pack and ship imperfect produce. Pressure to keep supermarket shelves full for appearance’s sake, losses during food processing and storage problems also lead to food being wasted.

Initiatives that aim to make more imperfect fruit and vegetables available, such as Woolworth’s Odd Bunch campaign, go some way to reducing this problem, but more needs to be done.

Our research estimates that if food waste was halved across the food supply chain, Melbourne could save 1.8 million hectares of land, 90 million litres of water and avoid 1.3 million tonnes of greenhouse gases each year.

We need to halve food waste

In recognition of the significant challenge that food waste represents to sustainable food systems, the new Sustainable Development Goals set a target to halve the global food waste per person that is generated by retailers and consumers by 2030.

The United States government has also set a national target to reduce food waste by 50% by 2030. It has established a cross-sector partnership of stakeholders across the food system to tackle the problem.

The UK government has been an early mover in taking action to tackle food waste. In 2007, it launched the WRAP Love Food Hate Waste program aimed at reducing food waste. An evaluation in 2012 showed that avoidable waste of food and drink (that could have been eaten) had fallen by 21% in five years following the launch of the program.

Most of this reduction has been in household food waste. The WRAP program is now working with the food industry to reduce waste in other sectors. The successful UK Love Food Hate Waste program aimed at reducing household food waste has been taken up by state governments in Victoria and New South Wales.

Australia is developing a national food waste strategy – the Food Waste 2025 Strategy – and stakeholders from across the food supply chain meet this month to discuss how to reduce food waste.

Australia should follow suit in setting a target to halve food waste across the food supply chain to put Australia’s food system on a more sustainable footing.

*Correction: This figure has been updated. It previously incorrectly stated that Melbourne’s food waste is enough to feed 2,000 people per year.

Seona Candy is a research fellow on the Foodprint Melbourne project, which is funded by the Lord Mayor's Charitable Foundation. Project partners include the City of Melbourne and the peak bodies representing the local government areas in Melbourne's city fringe foodbowl. She has previously received funding from an Australian Research Council Linkage grant on the project ‘Modelling policy interventions to protect Australia's food security in the face of environmental sustainability challenges’ (LP120100168), a collaboration between researchers at the Victorian Eco-Innovation Lab (VEIL) at the University of Melbourne, Deakin University and Australian National University. She is currently also receiving funding from the Cooperative Research Centre for Low Carbon Living for a project investigating urban innovations for post-carbon resilient cities.

Jennifer Sheridan is a researcher on the Foodprint Melbourne project, which which is funded by the Lord Mayor's Charitable Foundation. Project partners include the City of Melbourne and the peak bodies representing the local government areas in Melbourne's city fringe foodbowl.

Rachel Carey is a Research Fellow on the Foodprint Melbourne project, which is funded by the Lord Mayor's Charitable Foundation. Project partners include the City of Melbourne and the peak bodies representing the local government areas in Melbourne's city fringe foodbowl. She is also a Research Fellow on the project 'Regulating Food Labels: The case of free range food products in Australia', which is funded by the Australian Research Council.

The Bropkas meet the grid

In what must surely be a first for the Conversation, I am writing this post from the village of Sakteng in remote eastern Bhutan. That I can do so is a remarkable testimony to the will of the Bhutanese government in the electrification of what has to be one of the most difficult countries in the World to electrify.

Sakteng is one of Bhutan’s two main Bropka settlements. To get to Sakteng we walked from Merak, the other main Bropka settlement. It took us 8-hours trekking over the Nakchung pass at 4,100 m, though the locals take only half that time. From Sakteng to the road head is another 2 hours walk.

The Bropkas are yak herders that originate from Tibet, and inhabit the high mountains along the north eastern border of Bhutan and Arunachal Pradesh in neighbouring India. In many respects, Bropka life seems little changed from time immemorial, governed by the seasonal movement of their yak herds up and down the precipitous Himalayan mountains slopes. Traditional dress remains very much the order of the day with men in their dear skin jackets and woman adorned by their astonishing yak fur hats. But lives in these remote villages have changed in very real and tangible ways.

Bropka women from the village of Merak in eastern Bhutan, with their distinctive yak-fur hats.

Despite the road only just now reaching Merak, and not planned to get to Sakteng for a few years yet, both villages are on the grid, and have been for almost 10 years. Mobile telephony arrived soon after electricity.

A nation defined by steepness

Like few other countries, Bhutan is defined by steepness.

As anyone who has flown into the only international airport at Paro understands, precipitous slopes rise alarmingly even in the flattest parts of the country. Everywhere, the densely forested slopes are covered with landslide debris - primed for further collapse given the slightest nudge. I doubt that there is any country with a greater steepness index. One of the Himalaya’s most iconic images, the Taktshang monastery, testifies to the way the Bhutanese so readily accommodate this steepness in their daily life.

The Taktshang (Tiger’s Nest) Monastry, Bhutan.

By comparison with other segments of the Himalaya, the Bhutanese frontal ranges bordering the Indian plains of Assam and West Bengal are unusually steep. The steepness has afforded a natural defence that has helped isolate this remote kingdom for generations. The traditional Bhutanese strongholds lie in regions of comparatively low relief at 1500-3000 metres elevation, between the steep frontal ranges and the towering peaks of the high Himalayan along its northern border with Tibet. In more recent times this very steepness has created political distress of its own kind, as once welcome Nepali settlers of southern borderlands were evicted creating some 200,000 refugees.

But its topographic steepness comes with another penalty - the steep cost of moving things around.

On this trip we started our geological work in the south east corner of the country near the outpost of Daifam. By the way the crow flies it is just 250 kms from the nation’s capital Thimphu.

You can’t get to Daifam from Thimphu without leaving Bhutan and traversing through Assam. The quickest route is via the border town of Phuntsholing, 5 hours from Thimphu, and then another 9 hours via Assam. Alternatively you can take Bhutan’s main “highway” east from Thimphu to Trashigang (20 hours), down to Sandrup Jongkhar (5 hours) and across Assam (5 hours). Crows would appear to have it easy in Bhutan.

The isolated villages in the mountains to the north of Daifam are also mostly connected to the grid. To do so required carrying all the poles and wires, often up to a day’s walk up steep slopes through thick forest. Remote rural houses are provided with 100 units of electricity free, but do not go close to consuming that.

In the Bangtar district, on the southern border between Daifam and Sandrup Jongkhar, we met the electrical engineer helping build the transmission line that will send power from a hydro plant near Mongar in the north down to Assam in India. He explained it in some places it will take 2-days by foot to carry the material for the poles and wires from the road head to the proposed transmission route. All of Bhutan’s grid supplied electricity is sourced from hydro, and exports already greatly exceed domestic consumption.

The question of coal

Back in Australia, our coal lobby is fond of quotes of the ilk … “_Only when Third World children can do homework at night using cheap coal-fired electricity can they escape from poverty” .

And at least some in our government seem of a like mind.

Why, might we ask, does it matter that it is just “cheap coal-fired” electricity that alone will alleviate poverty? Why does not cheap hydro, geothermal, nuclear or whatever else, also do the trick?

No doubt coal has been a useful source of electricity in the third world, and will likely remain so for some time given that not all countries are endowed with the hydro resources of the Bhutanese. But is clear that Bhutan puts paid to the idea that coal alone can alleviate poverty.

But Bhutan also shows that there is something more fundamental that our coal lobby is loathe to acknowledge, and it speaks to the very paradox that lies at the heart of their claim - given that cheap coal has been around powering electricity systems for over 150 years, why are any children still living in poverty?

Could it be that the purported saviour of the world’s poor - the coal industry - doesn’t really have such a flash track record in the altruism stakes after all?

Bhutan shows that it is not really coal or any other source of energy that is the missing ingredient in providing electricity to children of the Third World.

Despite the immense impediment to transporting anything in such incredibly steep and forested terrain, Bhutan’s remarkable program of electrification suggests the real missing ingredient in providing access to energy is the will of government.

Disclosure

Mike Sandiford receives funding from the Australian Research Council for his geological research.

Worth crowing about? Birds that can problem-solve do best in cities. Gypsytwitcher/shutterstock.com

Life in the city can be stressful – for birds just as much as people. For humans, cities are expressly designed to put roofs over heads and food within easy reach, but the opposite can be true for many urban birds. They can find food and shelter harder to come by in the concrete jungle – with some notable exceptions.

For any species in any habitat, survival is about problem-solving and adapting to the environment. So what street smarts do city birds need? And why do some species, such as lorikeets, crows and ravens, seem to dominate our urban landscapes?

In general, urban birds must be bolder than those that remain in natural habitats, as can be seen by the boldness (or “habituation”) with which some species will forage for food with people nearby. But they also need to be able to avoid or retreat from unfamiliar objects or situations if they seem dangerous.

City birds also need to withstand exposure to a wide range of pathogens. A study of birds in Barbados found that urban birds have enhanced immune systems relative to their country counterparts.

While we have changed the environment in which some birds live, reducing resources in terms of food and shelter and increasing the number of pathogens that may impact their health, some birds have largely benefited from the new way of life.

Winners and losers

Within the urban ecosystem, there are winners and losers in the bird world. The suburban landscape, for example, now provides more nectar from flowers than native vegetation due to the gardens that people have established. This is a big help to nectar-feeding parrots such as Rainbow Lorikeets.

A recent study in Sydney found that the lorikeets benefit from the increased abundance of flowers in urban areas, and their numbers were higher in the leafy suburbs than in bushland.

But if urban areas are such a rich source of nectar, why are some nectar-feeding species declining?

The Regent Honeyeater feeds mainly on nectar and other plant sugars. It has been seen in orchards and urban gardens, but is listed as critically endangered by the federal government.

This is partly because widespread clearance of woodland habitat has led to the increase of the aggressive Noisy Miner and Red Wattlebird. These species find it easy to “bully” other birds in open habitats. Noisy Miners have been observed pulling apart Regent Honeyeaters' nests as they were being built.

Regent Honeyeaters, in contrast, are less adaptable to changed landscapes, because they are migratory and rely on detailed knowledge of existing food sources. If these resources are changed or removed, they may not have enough interconnected patches of habitat to move safely towards new resources – potentially leaving them vulnerable to cats, foxes and aggression from other birds.

Habitat loss can threaten some bird species or even leave them at risk of dying out if they do not locate alternative resources. The ability to find new food sources therefore becomes a valuable survival skill.

What’s more useful: flexibility or intelligence?

For some bird species, flexibility in finding food is crucial in making a successful switch to urban environments. One example is the Grey-crowned Babbler, which is endangered in Victoria, but my colleagues and I have documented it living in a suburban area in Dubbo, New South Wales.

This species usually nests in coniferous woodland and forages in the leaf litter beneath the trees. But in Dubbo, we saw these birds feeding on lawns, in playgrounds and even in leaf litter along a train track at the back of urban housing, sometimes visiting backyards along the way. This suggests that these birds can survive the loss of their woodland habitat by being sufficiently adaptable to life in the suburbs – as long as they can continue to find enough food, disperse between nearby groups and have access to native nesting trees.

For other species, such as crows and ravens, intelligence seems to be the key. These species can survive anywhere in the urban sprawl, including places where trees are scarce but rubbish bins are everywhere. Crows and ravens can literally pull food out of a bin and eat it – clearly a learned behaviour that has resulted from problem-solving.

These birds are highly opportunistic and social, allowing them to learn new ways of adapting to the almost complete removal of their natural environment.

Survive and thrive

What we can deduce from these examples is that some birds, like Rainbow Lorikeets and Grey-crowned Babblers, can adapt successfully to the urban sprawl as long as some characteristics of their habitat still remain. Other species, such as crows, have gone a step further and worked out how to survive purely on urban resources – effectively making a living in an environment that is completely unnatural to them.

This suggests that the more we urbanise an area without natural aspects, the less bird diversity we will have – and the more our urban areas will come to be dominated by those few species that are hardy, clever or adaptable enough to thrive.

Luckily, some councils in Australia and cities throughout the world are bringing the natural aspects of the forest back into the concrete jungle, so that a wider range of birds might survive here. More research is needed to work out exactly what each species will need, but planting more native plants is always a good start.

Kathryn Teare Ada Lambert does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Springtails come in variety of shapes and sizes. Springtail image from www.shutterstock.com

You’ve probably never heard of them, let alone seen them, but it’s likely you have some in your home. Springtails are only 1-2 mm long but are ubiquitous, found in every habitat except the oceans.

Springtails are closely related to insects – they have six legs and a head, thorax and abdomen – but are not insects because they lack wings and have soft bodies and hidden mouthparts. Springtails are known scientifically as Collembola.

Collembola are unique in carrying a jumping organ beneath the abdomen, held in place with hooks. When released, the jumping organ springs free, hitting the ground and forcing the animal to leap into the air, hence their common name.

In the wild, springtails can be found in leaf litter, soil, under bark, in sand, under stones, in tree canopies and even in caves and ant and termite nests. In termite nests they may control fungal growth. Most importantly, springtails have been shown to be useful bioindicators of environmental change.

Some male springtails perform a complex mating dance to attract the female. Other species are carried by insects for dispersal or feeding purposes.

A springtail mating dance as shown in David Attenborough’s Life in the Undergrowth.

In Australia, there are several thousand species, most found only in this country. In any garden compost heap there will be millions of individuals belonging to about ten species. Native springtails may be brightly coloured and patterned; white, if living in soil; or black if living in exposed habitats such as mountain tops, beaches or coral reefs.

Native springtails can be brightly coloured - this is Acanthanura from Tasmania. Copyright Andy Murray Another Tasmanian springtail, Temeritus. Copyright Andy Murray Springtails in the home

Three species are commonly found inside buildings, all with an elongated bodies and belonging to the family Entomobryidae. These are introduced species, which were probably brought to Australia in soil and animal fodder before quarantine controls were put in place.

If you put sticky or water traps in a garage or shed, for instance, after only a day or two springtails should appear floating on the water or trapped in the glue. You might have to use a magnifying glass to see them.

Cellars invariably harbour several species. One unusual example was in a doctor’s surgery, where every morning springtails were found floating in the then-cooled water of the steriliser, having emerged overnight from their hiding place and fallen in.

This Entomobrya springtail is from the family often found in homes. Andy Murray/Flickr, CC BY-SA

Springtails are dispersed involuntarily in several ways. They can be transported in air currents and in flowing water in drains, as well as being carried in timber, packing materials and footwear, by domestic animals and on fresh vegetables and house plants. Species on vegetables could only become established in pot plant soil.

Household springtails feed on fungi and other microorganisms, which can be present in clean, relatively dry habitats such as within walls and under floors.

One species of springtail is sometimes found in baths and basins, having crawled up drain pipes. This species is most commonly observed in summer when conditions outside are particularly hot and dry, but cooler, moister conditions exist indoors.

Springtails only very rarely become a nuisance, not because they cause allergies or bite, but because they sometimes become extremely numerous in domestic situations. The few records of springtails being found on the human body have almost all been shown to be a case of mistaken identity.

If springtails become too numerous in a house, it is best to use normal cleaning methods, such as vacuuming carpets and sweeping floors to reduce populations. But if the source population is in walls or under floors, this won’t work.

Chemical methods may not be successful as, on the whole, these animals are resistant to pesticides. Instead, the source of the population should be found, which could be pot plant soil, adjacent garden soil, or debris under the floor, and the habitat cleaned out.

Domestic springtails are harmless to us and do not carry diseases. In the natural environment they are considered “goodies” as they are detritivores and contribute to nutrient cycling by breaking down organic matter by grazing on microorganisms on dead leaves and in logs.

In the home, therefore, springtails are not to be feared. In the wild, they play a valuable ecological role and many species are colourful and have intriguing habits.

This article is part of a series profiling our “hidden housemates”. Are you a researcher with an idea for a “hidden housemates” story? Get in touch.

Penelope Greenslade does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

The killing of tourist Cindy Waldron by a saltwater crocodile while swimming north of Cairns on Sunday has reignited the debate about how to keep people safe from crocs. Federal MP Bob Katter has called for a bigger crocodile cull, although the Queensland government has once again ruled this out. There are very good reasons for this decision.

The evidence suggests that calls for complete deregulation of croc hunting are based on flawed arguments. The easiest way to keep people safe is to make sure they understand the risks.

What have we been doing about crocodiles?

Crocodile populations have been managed in northern Australia since the early 1970s. Before that, it was open season: three decades of hunting wiped out 95% of wild crocodiles, although getting them all proved impossible.

Many hunters grew to respect these unequivocally Australian “beasts”, supporting their subsequent protection. Yet their numbers bounced back much faster than anyone expected. Questions were soon being asked about the wisdom of allowing their recovery.

Sub-adult saltwater crocodile basking on a tidal mud bank, a popular sight for the many tourists who visit northern Australia each year. Adam Britton

Recognising the value of crocodiles to people and ecosystem health, the Northern Territory government changed tack. Crocs became tourism icons, their eggs and skins were harvested sustainably to create local jobs and a fledgling industry, and safety issues were managed by the targeted removal of “problem” crocodiles, alongside visible media campaigns about staying safe. Despite differences between states and territory, the same basic approach is still used.

Has it been effective in saving lives? The first subsequent recorded fatal attack in Queensland happened in 1975, when Peter Reimers was killed while wading in a creek near Mission River. This was only a year after the crocodile population had been protected because it was on the verge of disappearing. Three decades of unregulated hunting hadn’t saved Reimers' life.

The latest statistics as compiled by CrocBITE show 112 attacks between 1971 and May 2016, 33 (30%) of them fatal. That’s an average of 2.5 non-fatal attacks per year and 0.7 fatal attacks per year across Western Australia, the Northern Territory and Queensland. The rate has increased slightly over the past decade, but crocodile attacks remain extremely rare in Australia.

Number of reported saltwater crocodile attacks per country (April 2007 to April 2014). Fatal proportion in red, percentage shows fatality rate. Adam Britton / CrocBITE

The average size of crocodiles is increasing as the population continues to mature towards full recovery. However, given the very low number of attacks, it’s difficult to assess if this has had any impact on the fatality rate.

Attacks usually happen because people get in the water with crocodiles. Such an obvious cause should be easy to prevent, and indeed this is the case.

Attack risk in Australia is low, largely because of the success of long-running campaigns to warn people of the dangers of swimming in crocodile-populated waters.

What lurks beneath? If you’re in crocodile habitat and you find water, always assume that it harbours a crocodile. Adam Britton

Those who live locally are generally most keenly aware of the dangers. Sadly, a disproportionate number of attack victims are visitors who aren’t as aware of the risks. The real problem can therefore be interpreted as a failure to communicate risk, and therein lies the solution.

How to not get eaten by a crocodile

Crocodile attacks are traumatic, unfortunate and potentially tragic incidents that generally can be avoided. Australia has an excellent track record in saving people from crocodile attack. Despite having more saltwater crocodiles than any other country, we have low fatality rates because our management and education program is world-class.

Other countries with crocodiles come to Australia for advice on how to manage their crocodile populations and prevent conflict with people.

But there’s still a grey area for many people. How do you know whether it’s safe to swim in northern Australia? What’s the risk of doing so?

We make decisions every day to assess risk, whether we’re driving, walking down the street, swimming in a pool, or taking a boat out on the water. We’ve been trained to minimise the risks we face.

The same is true of going into the bush and facing potential dangers from snakes, mosquitoes or other animals. Sometimes accidents will happen, often because someone decided to push their luck.

Distribution of saltwater crocodiles throughout their range, including northern Australia. Green are viable populations, orange are recently extirpated populations and blue represents their potential for movement within and between countries. Brandon Sideleau / CrocBITE

But with crocodiles the rules are simple: don’t enter the water in crocodile habitat. In these areas, stay away from the water’s edge, don’t disturb water consistently in the same place, don’t approach or tease crocodiles, camp at least 50 metres from the bank, and don’t go out in small, unstable boats.

Warning signs about crocodiles are there for a reason, to allow you to make an informed decision about your personal safety. Ignore them and you may get away with it, but eventually you will not.

The name ‘saltwater crocodile’ is misleading. They are equally at home in freshwater habitats. Adam Britton

There’s little doubt that Australia knows how to manage wild crocodile populations. The risk of being attacked by a crocodile here is vanishingly small because crocs and people are managed effectively.

We already have a limited cull of crocodiles; the targeting and removal of specific animals that, through their actions, pose an elevated risk to the public. A wider cull won’t gain anything, at the cost of local livelihoods and our natural resources.

This article was co-authored by Erin Britton, a biologist at Big Gecko Crocodilian Research in Darwin.

Adam Britton received funding from Charles Darwin University to develop the technology for the CrocBITE database.

Summer stayed into autumn in many parts of Australia. Bondi image from www.shutterstock.com

It’s the same old story: with 2016 on track to become the hottest year on record globally, and record-breaking heat already evident around the world, Australia has just experienced its hottest autumn on record.

Figures from the Bureau of Meteorology indicate Australia has experienced its hottest autumn on record. Bureau of Meteorology

The Bureau of Meteorology has reported that for average temperatures across Australia, this has been the hottest March-May period ever recorded – beating the previous record, set in 2005, by more than 0.2℃.

Within this period, March was also the hottest on record, while April and May were each the second-warmest in a series extending back to 1910.

Temperatures were well above average across much of the country, especially in the east. Bureau of Meteorology Why so hot?

El Niño events tend to cause warmer weather across the east and north of Australia and the major El Niño of 2015-16 undoubtedly contributed to the extreme temperatures experienced across these areas.

However, climate change also played a significant role in our warmest autumn. Previous work, led by ANU climatologist Sophie Lewis, indicates that the human influence on the climate has made a record-breakingly hot autumn roughly 20 times more likely.

In other words, without climate change we would be much less likely to experience autumns as warm as this one has been in Australia.

How we’ll remember autumn 2016

In the past few months, Australia has seen many extreme hot weather events. Melbourne experienced its warmest March night on record, while Sydney had a run of 39 days with daytime highs above 26℃, as the summer heat continued long into March.

But it’s the coral bleaching event on the Great Barrier Reef that will likely linger in our memories the longest. Some 93% of the reef was found to be affected by bleaching and recent surveys have revealed that more than one-third of coral in the northern and central parts of the reef have died.

Without climate change, a bleaching event like this would be virtually impossible.

The extreme heat over Australia this autumn and the associated damage to the reef are also having an effect on the election campaign. As public concern over the future of the reef grows, the parties are being asked to defend their climate change policies.

Both major parties have made election commitments to the reef, with the Coalition announcing an extra A$6 million to tackle crown-of-thorns starfish (adding to a further A$171 million committed under the 2016 budget), and Labor an extra A$377 million over five years (A$500 million in total). While both Labor and the Coalition aim to improve water quality in the reef through their policies, the coral bleaching and death this year is linked with warm seas.

Whether we’ll be able to save parts of the reef largely depends on whether we reduce our greenhouse gas emissions and manage to prevent the rising trend in temperatures from continuing.

Andrew King receives funding from the ARC Centre of Excellence for Climate System Science.

Putting gorillas behind steel and glass might seem harsh, but these barriers help keep them safe. Tim/Zoo Atlanta Flickr/Wikimedia Commons, CC BY

The death of Harambe, a 17-year-old silverback Western lowland gorilla shot dead by Cincinnati Zoo staff after a four-year-old boy fell into his enclosure, has sparked anger and controversy.

One lesson we can take from this sad episode is the need to be realistic about the conditions in which gorillas and other captive animals live. If we accept that gorillas are going to be kept in zoos, we need to make sure those zoos don’t fail these animals by letting situations like this arise.

Harambe and the young boy.

Gorillas are obviously potentially dangerous to humans. We are a danger to them too, not least because our genetic closeness makes gorillas vulnerable to many human diseases.

As unpalatable as it seems to zoo visitors who might want to see animals living as “naturally” as possible, gorillas need to be kept behind glass, steel mesh or wide divides – for their own safety as well as ours.

Safety-first zoo design

One of the biggest questions about the Cincinnati Zoo incident is how the young boy could so easily have fallen into Harambe’s enclosure and come into direct contact with him. In light of this, there are certain principles that can be followed for the safe design of enclosures for large animals.

If an outdoor enclosure has some type of moat for containment, it may be a deep concrete moat with shallow water (less than 50cm) for gorillas to use without risk of drowning (gorillas can’t swim).

According to one set of recommendations, the typical minimum barrier should be 3.65 m high and 3.65 m across, but there is no law concerning minimum standards for gorilla enclosures. For extra security, a second barrier, sometimes electrified, is needed to keep people away.

In terms of minimum standards, the Cincinnati Zoo enclosure is suitable. But for great apes such as gorillas, it should no longer be acceptable simply to meet minimum standards. This is as true for containment as it is for the animals' other needs: space, complexity, and behavioural and psychological stimulation. The cost of building optimal enclosures for gorillas runs into millions of dollars, which places constraints on zoos who rarely have the funds to upgrade or redevelop enclosures. Who should fund these improvements?

All zoos have regulations and procedures to follow for risk management, including animal escape and recapture. Additional precautions are taken for all incidents or interactions with those considered dangerous species (such as big cats, great apes, elephants and so on).

There are strict legal requirements for protecting the public. But because of the rarity of such events, zoo staff may be inexperienced with situations involving human intruders (accidental or otherwise) in an exhibit.

Are gorillas ‘gentle giants’?

In 1996, a three-year-old boy fell into a similar enclosure at Brookfield Zoo. While the zoo visitors were also screaming and yelling, an eight-year-old female gorilla, Binti Jua, “rescued” the boy by carrying him to zoo staff at a side entrance. As animal researcher Marc Bekoff points out, Binti Jua was hailed as a gentle “heroine”, whereas Harambe was treated as a threat, but in both cases the gorillas were in situations where they had no control over the outcome.

It is impossible to say for certain whether Harambe would have become aggressive. He appeared to show behavioural signs of stress – hardly surprising given that people were shouting and screaming at him. Gorillas are sensitive and respond to non-verbal behaviour, such as towering over them or staring at them, which can be seen as a threat.

When faced with a stressful, noisy and threatening situation, gorillas – like most other animals, humans included – have a physiological “fight or flight” response. It is hard to predict how any individual will react under stress, but based on the video footage, Harambe did not appear to be behaving aggressively.

Silverbacks are powerful animals, weighing up to 180kg. When they are living in stable groups and not facing a threat, they are indeed gentle, but adult silverbacks can engage in infanticide when taking over a new family group.

A 2005 study found that the behaviour and welfare of gorillas in zoos are influenced by the number of people nearby, how close they are, and how much noise they are making. While zoo visitors can behave in almost any way they want, in the wild there are strict guidelines for tourists visiting gorillas.

To avoid disease transmission, behavioural disturbance and stress for wild gorillas, tourists who visit their native habitats must be over the age of 16, and in groups of no more than eight. The guidelines allow them to spend one hour quietly watching from a distance of about 10m.

Gorillas may be “gentle giants” when treated with respect and awe, but they are so much stronger than us.

Wild gorillas: look, but don’t touch. Augustine Tours/Wikimedia Commons, CC BY Expectations vs reality

When gorillas are housed in zoos, their exhibits must be designed from three perspectives: the safety and wellbeing of gorillas in the enclosure; the safety and satisfaction of visitors; and the safety and ease of maintenance by keepers and other staff.

These aims aren’t always mutually compatible. Zoo visitors might expect gorillas to be visible, active and “entertaining”, whereas the gorillas themselves are likely to seek quiet, secluded areas, and to spend much of their day resting or foraging.

Zoos and wild gorilla tourism sites must manage their visitors' expectations, so that all visitors understand that animal welfare and comfort take priority over optimal viewing.

We also can’t pretend that gorillas have control over their lives in captivity or even in natural habitats. They are impacted by human activities in all the places they live. Conservation is far more complicated than merely ensuring that gorillas have somewhere to live.

Zoo-based management programs have to deal with issues such as providing long-term care for old gorillas, who can reach 50 years of age. Captive breeding programs also have to deal with a “surplus” of males, because only a subset of silverbacks form family units or harems, which feature multiple females. In the wild there are many different group formations, including those with multiple silverbacks, but in captivity it is harder to manage social groups, as there is rarely space to separate individuals when aggression occurs.

Meanwhile, sanctuaries in Africa are struggling to care for orphaned gorillas as a result of the bushmeat trade. There is no truly safe wild haven for gorillas. Populations of critically endangered Western Lowland gorillas are declining, mainly as a result of the Ebola virus, which has killed thousands of gorillas in the Congo Basin, as well as commercial hunting and human disease.

Do gorillas belong in zoos? Why do zoo visitors want to see large animals in urban zoos? Are gorillas safer in the wild than inside enclosures and, if so, where? These are questions on which there will inevitably be strong differences of opinion.

But one thing we should all agree on is that we must strive to be compassionate and foster peaceful co-existence between people and other species, and work towards creating safe environments for gorillas with minimal human impact.

We can’t pretend that a moated enclosure without bars is any less of a cage than one with mesh. If keeping them safe in a zoo means putting a bigger barrier between us and them, or only letting us view them via hidden cameras as they live in a more protected and secluded exhibit, then so be it.

Carla Litchfield does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Nemo is actually a 'false clownfish'. Motoya Kawasaki/Flickr, CC BY-NC-ND

Anemonefish, or clownfish, were made famous by the 2003 Disney-Pixar film Finding Nemo, and are about to play a starring role in the sequel, Finding Dory. They are well known for their special relationship with anemones, which provide a safe place to call home.

But anemonefish face a number of threats. Some researchers have warned of an increase in the wild-caught anemonefish trade, as happened following Finding Nemo.

Anemones, on which anemonefish depend, are threatened by warming seas in a similar way to corals. In fact anemones were affected by the recent coral bleaching on the Great Barrier Reef, which recent updates show has left a third of coral colonies dead or dying in the north and central parts of the reef.

So will Nemo be left homeless?

A healthy (left) and bleached (right) bubble-tip anemone (Entacmaea quadricolor) on the Great Barrier Reef. Ashley Frisch Nemo and his 27 cousins

There are 28 species of anemonefish. Although some people call this group “clownfish”, technically this name is only used for one species, Amphiprion percula. “Nemo” (A. ocellaris) looks similar, but is actually known as the “false clownfish”.

Anemonefish are famous for their special relationship with anemones. Although they can survive in aquariums without anemones, in nature they rely on anemones for protection from predators.

The pink anemonefish (Amphiprion perideraion) in a bleached anemone (Heteractis magnifica) at Christmas Island. JP Hobbs.

In return for providing a safe home, the resident anemonefish will provide nutrients and defend the anemone from predators such as butterflyfish. Both the number and size of anemonefish is linked to the size and number of anemones – and vice versa. Therefore, any decrease in one partner affects the other.

The collection of anemones and anemonefish for the aquarium trade has to be managed properly to ensure the future of anemonefishes. Anemonefish can be easily bred in captivity and this provides a reliable source for aquarium enthusiasts without impacting wild populations.

Cinnamon anemonefish (Amphiprion melanopus) in a bleached anemone (Entacmaea quadricolor) on the Great Barrier Reef. Ashley Frisch

Ten species of anemones are inhabited by anemonefish. The highest diversity of anemonefish occurs in Indonesia, where anemonefish species outnumber anemones. As a result, different species of anemonefish have learnt to share the same anemone.

In most other locations, anemonefish aggressively prevent other species from entering their anemone. Anemonefish species differ in the number of anemone species they associate with.

Clark’s anemonefish (Amphiprion clarkii) in a bleached anemone (Cryptodendrum adhaesivum) at Christmas Island. JP Hobbs.

Clark’s anemonefish (A. clarkii) can live in all ten anemone species and is widely distributed throughout the Indian and Pacific Oceans. In contrast, McCulloch’s anemonefish (A. mccullochi) inhabits only one species of anemone and occurs only on reefs around Lord Howe Island.

After hatching, anemonefish larvae use their keen sense of smell to find their preferred anemone species and avoid unhealthy (bleached) anemones.

Anemones in hot water

Anemones are closely related to corals and get their colour from microscopic algae (zooxanthellae) that live symbiotically within the tissue of the anemone. Like corals, anemones expel their algae and turn white when they become stressed.

This process – termed “bleaching” – is usually in response to periods of elevated seawater temperatures. All ten species of anemones are susceptible to bleaching, which can result in a decrease in the size and number of anemonefishes and reduced reproduction.

McCulloch’s anemonefish (Amphiprion mccullochi) in a bleached anemone (Entacmaea quadricolor) at Lord Howe Island. Justin Gilligan.

If seawater temperatures remain high for too long, then bleached anemones will die. In 1998, a prolonged period of elevated water temperatures in Japan resulted in mass mortality of bleached anemones and local extinction of anemonefish.

In March 2016, the Great Barrier Reef experienced a severe bleaching event due to elevated water temperatures associated with a strong El Niño event. There was mass bleaching of both corals and anemones.

Marine biologist Jean-Paul Hobbs studying anemonefish (Amphiprion mccullochi) and their host anemones (Entacmaea quadricolor) at Lord Howe Island. Justin Gilligan.

In April 2016, elevated water temperatures also caused mass bleaching of corals and anemones off north-west Australia, including Christmas Island. Bleached anemones have also recently been reported elsewhere in the Pacific Ocean, Indian Ocean and in the Red Sea.

The future of the bleached anemones and their resident anemonefish will depend on how quickly the water temperature returns to normal. If the temperature decreases swiftly, bleached anemones can regain their colour (reabsorb zooxanthellae) and survive.

However, the frequency and intensity of bleaching events are predicted to increase as the climate changes. Consequently, there are serious concerns about the ability of anemones and anemonefish to cope with rising water temperatures.

Reducing global greenhouse gas emissions will limit subsequent bleaching events and help ensure the future of Nemo and its relatives.

Jean-Paul Hobbs currently receives funding from Curtin University and Christmas Island Divers Association. His past research on anemones and anemonefishes has been funded by James Cook University, ARC Centre of Excellence for Coral Reef Studies, Great Barrier Reef Marine Park Authority, Lord Howe Island Marine Park, Parks Australia, WA Department of Fisheries, Wet n Dry Adventures Christmas Island and the Australian Government Department of the Environment.

Ashley J Frisch has received funding from the ARC Centre of Excellence for Coral Reef Studies, James Cook University, and the Great Barrier Reef Marine Park Authority.

The problems caused by mass bleaching on the Great Barrier Reef have continued to deepen, with the latest estimates based on results from our surveys showing that 35% of corals are now dead or dying along the northern and central sections of the reef north of Townsville.

We have been tracking this severe bleaching event for months, documenting the damage as abnormally high water temperatures caused the coral to bleach, losing the algae that live within their tissues and supply most of the corals' energy.

Although corals can recover from bleaching when water temperatures drop, they can also die if they are without their algae for too long. From our surveys, we estimate this has now happened to one-third of the corals on reefs north of Townsville and to half of the corals on reefs that were hit hardest by the bleaching event.

The scale of the damage

For this latest survey, my colleagues and I carried out in-water surveys of corals on 84 reefs, spanning 1,300 km from Townsville to the Torres Strait, between mid-March and mid-April this year. We counted the number of coral colonies that were either recently dead, bleached completely white, partially bleached or healthy, as well as quantifying the percentage cover of hard corals and other organisms at each reef.

When you’re underwater, it’s easy to spot corals that have recently died due to bleaching because their white skeletons are coated in a thin film of greenish-brown algae. Over time, the algae grows to form a thick mat that obscures the skeleton – a hallmark of long-dead corals that are not victims of the recent bleaching. Our surveys did not include these colonies.

Corals that are bleached totally white, having lost nearly all of their symbiotic algae, have an extremely low chance of recovering because it takes several months for the algae to come back. In contrast, most corals that are only partially bleached will survive and recover quickly.

In the reef’s central section, between Cairns and Townsville, colonies tended to be partially bleached instead of completely white or dead. We estimate that fewer than 5% of colonies will die on many of these reefs.

But on the reef’s northernmost section, north of Cooktown, we estimate that more than half of the coral colonies on many reefs have died.

What do these figures really mean?

Corals are made up of tiny modules, called polyps, that are joined together to form colonies. Most of the polyps in each colony can reproduce, and this obviously means that larger colonies can produce more larvae.

Similarly, reefs with more different colonies living on them can produce more larvae overall, providing a supply of new corals that can disperse to nearby damaged reefs and kick-start their recovery.

In places where corals have died on just a few reefs among many other healthy reefs, the supply of larvae from the neighbouring healthy reefs can facilitate more rapid recovery.

But in places where coral deaths are spread across most of the reefs, such as the stretch north of Cooktown, the coral larvae needed to recolonise the reefs have to travel much longer distances and this slows down the recovery.

Recovery prospects

This shows why coral bleaching is particularly damaging to reefs: its effects can be apparent over a scale of thousands of kilometres. Other disturbances, like cyclones, can also kill lots of coral, but their effects are usually more localised, meaning that recovery is easier.

Based on previous bleaching events, it can take several decades before these reefs recover, and much longer before the oldest and largest colonies are able to re-establish themselves. Some areas of the reef that were severely bleached in 1998 still haven’t recovered. The fear is that the time between bleaching events is now shorter than the time needed for reefs to recover.

Ocean currents are crucial to reef recovery, because of the importance of dispersing coral larvae for repopulating damaged reefs. On the Great Barrier Reef, the East Australian Current helps to transport larvae from north to south. However, this current begins its southward path at around 18º South (just north of Townsville), meaning that this current will be little help (and will in fact be an active hindrance) to the recovery of the most severely bleached reefs beyond that.

Another factor that impedes recovery is that bleached corals have lower reproductive output after a bleaching event. This means that even colonies that don’t die this year will contribute fewer larvae in the coming years.

Fixing the damage?

Coral bleaching events happen mainly when ocean temperatures are abnormally warm. Consequently, reducing greenhouse gas emissions is the main way we can help to prevent more global bleaching events from striking in the future.

Improving water quality and controlling outbreaks of crown-of-thorns starfish are also very important, because reducing coral loss due to these other factors can increase the resilience of the reef to bleaching.

Technological approaches, like shading reefs or artificially restocking reefs, might be considered for specific small reef sites, but they are not feasible for the conservation of the 2,300 km Great Barrier Reef, or for coral reefs on a global scale.

Mia Hoogenboom receives funding from Australian Research Council.

Ten years ago, An Inconvenient Truth opened in cinemas in the United States.

Starring former US vice president Al Gore, the documentary about the threat of climate change has undoubtedly made a mark. It won two Academy Awards, and Gore won the 2007 Nobel Peace Prize for his efforts to communicate human-induced climate change.

An Inconvenient Truth (AIT for short) is the 11th-highest-grossing documentary in the United States. According to Texan climatologist Steve Quiring:

AIT has had a much greater impact on public opinion and public awareness of global climate change than any scientific paper or report.

But has the film achieved what it set out to do – raise public awareness and change people’s behaviour in order to reduce greenhouse gas emissions?

Measuring the film’s impact

A public survey by the Pew Research Center for People & the Press found that in the months following the documentary’s release, the percentage of Americans attributing global warming to human activity rose from 41% to 50%. But how do we know whether AIT contributed to this increase?

Several studies have experimentally tested the impact of viewing the film. A UK study found that showing selective clips from AIT resulted in participants feeling more empowered and more motivated to make lifestyle changes to fight climate change.

Similarly, surveys of moviegoers and students found that watching AIT increased knowledge about the causes of global warming and willingness to reduce greenhouse gases. However, this increased willingness didn’t necessarily translate into action. A follow-up survey conducted a month later found little change in behaviour.

One novel approach found a 50% increase in the purchase of voluntary carbon offsets in areas where AIT was shown. This is encouraging evidence that the film did lead to tangible behaviour change. But again, the effect wasn’t long-lasting. A year later, there was little difference in carbon offset purchases.

An analysis of drivers of public attitudes towards climate change found a significant relationship between media mentions of AIT and public perception of the urgency of climate change. In other words, the film produced a significant positive jump in the general public’s perceptions of the issue.

This study also found that polarisation decreased after the release of AIT, pouring cold water on the claim that Al Gore polarised the climate debate. Rather, the polarised positions on climate science among Democratic and Republican leaders (one party broadly accepting the science, the other significantly rejecting it) was found to be the key driver of public polarisation on climate change.

This led the study’s author, Robert Brulle, to state:

I think this should close down forever the idea that Al Gore caused the partisan polarisation over climate change.

This body of research underscores the difficulties confronting any public awareness campaign. AIT was successful in raising public awareness of climate change, increasing willingness to change behaviour and, in some cases, actually changing behaviour.

However, the effect didn’t last long. This indicates that persistent communication efforts are required to promote sustained behaviour change.

Scientists critique An Inconvenient Truth

While AIT was effective among the general public, there is no tougher crowd for a science documentary than scientists. A survey of members of the American Meteorological Society and the American Geophysical Union found that among the scientists who had seen and rated AIT, 72% said the film was either somewhat or very reliable.

To put this in perspective, only 12% of scientists who had read Michael Crichton’s contrarian novel State of Fear rated it as somewhat or very reliable.

Going into more detail, an edition of GeoJournal had four scientists critique the scientific accuracy of AIT. Unfortunately, the panel was made up of two mainstream scientists and two contrarian scientists – a false-balance form of coverage that actually causes confusion rather than increases literacy in the context of media coverage. (For an incisive look at false-balance coverage of climate change, watch John Oliver’s statistically representative climate change debate.)

A statistically significant climate change debate

The outcome is somewhat predictable, with mainstream scientists reporting a more positive assessment of the accuracy of AIT than the contrarian scientists. Nevertheless, a useful overview of the exercise is provided by Texan climatologist Gerald North, who concluded that while there were some inaccuracies in AIT, on the whole it represented mainstream scientific views on global warming.

Ultimately, the factual inaccuracies in AIT were deemed inconsequential and don’t undermine the main message of the film.

Inspiring others

While most of the research into the impact of AIT investigates the direct effect on viewers, a potentially more significant impact is the film’s role in inspiring others to follow Gore’s example in communicating the issue of climate change to others.

Personally, I can attest to this influence. Before 2006, I hadn’t given much thought to the climate change issue. Watching AIT raised a number of questions about the human role in global warming.

With the issue salient in my mind, I got into conversations with family members who happened to reject the scientific consensus on climate change. This precipitated the founding of Skeptical Science, which led to me becoming a researcher in climate communication at the University of Queensland.

I’ve spoken to or know of many other climate communicators whose awareness of the issue dawned with their viewing of AIT. While the direct effect of the original screening of the film may have dissipated, the impact of those inspired to communicate the realities of climate change persists.

For me, the film precipitated a series of events that ultimately redirected the course of my life. An Inconvenient Truth wasn’t just behaviour-changing, it was life-changing.

No lab experiment can quantify that level of impact.

John Cook does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Australia is a land of extreme weather. Events such as the 2009 Victorian bushfires, the 2011 Queensland floods and Cyclone Yasi in 2013 are stark examples of climate-related risks faced by Australian households. Many homes are built in high-risk locations including floodplains, coastlines and bushfire-prone land.

The Climate Institute has today released a report detailing the critical role Australian housing plays in the economy, and the risks housing faces with a changing climate.

It also sets out the role of banks and insurers in promoting risk reduction and climate adaptation for Australian housing.

Built on sand

Housing represents many Australians' biggest financial commitment – including those who rent rather than buy. Housing accounts for up to one-third of the economy, through direct and indirect means and across sectors such as finance, insurance and construction. With population projections forecasting continued growth and attraction to risky locations, banks and other financial institutions have a crucial role to play in minimising the economic threat posed by climate change.

But while the role of land-use planning and insurance with regard to climate risks has been well documented, the role of banks as gatekeepers to housing finance has been largely overlooked.

As the Climate Institute’s report points out, banks have a “unique ability and incentive” to steer housing purchases, because they are the main providers of residential financing. As such, they have large financial liabilities if homes are lost to fires, floods or other climate effects.

There are a range of tactics banks might use to reduce or mitigate climate risk. For instance, they could favour lending on homes that meet specific risk-reduction requirements, such as raised floor levels for homes in flood zones, or fireproof construction materials in bushfire-prone regions. This approach could also be used in setting mortgage insurance premiums as well as the mortgages themselves. Another approach is to better apportion their exposure - by lending on a reduced percentage threshold of the total property value.

Westpac has a Climate Change Position Statement and both the Commonwealth Bank and NAB have committed in reducing carbon. But more needs to be done for housing.

If banks continue under a business as usual approach, they face the risk that many properties will be devalued over time, through continued exposure to extreme weather events. This represents a significant financial liability, especially when you consider that a home loan typically takes 30 years to play out – a similar time scale to the many climate impacts expected for Australia.

Banks are already making moves to restrict lending based on location.

But the report outlines several other things banks could do, such as:

• examine climate risk exposure in their current lending practices

• use their role as financiers to support good policy, by engaging policymakers and financial regulators

• encourage stakeholders, including the public, private sector and civil society sectors, to develop ways to minimise climate impact risks for housing

• ensure losses are addressed in an equitable way.

A climate insurance policy

The report also details how the insurance sector assesses risk to housing, and how it might improve its approach in the future, given the intersection of urbanisation, population trends and the trend towards living in climate-threatened areas.

The insurance sector has historically been seen as the messenger of housing market signals, because of its keen focus on assessing weather-related risk. But the 2011 Queensland floods highlighted many weaknesses in relying on insurance alone.

Many properties did not have adequate flood insurance, leaving many people without a home after losing their house to the floods. The Australian and Queensland governments and the private sector struggled to co-ordinate a cost-effective response, partly because of previous bad land-use planning decisions, but also because of the lack of adequate insurance cover.

A federal government levy helped the affected regions to “build better back”. Some chose to rebuild in the same high-risk locations.

Critically, gaps identified in building codes, land use and climate resilience still require a more co-ordinated response. The current Stage 2 coastal law reforms in New South Wales offer a potential example of how competing interests might be balanced.

At face value, this issue is a no-brainer. After all, risk mitigation is bread and butter for lending institutions and insurers, and we already know that extreme weather events are forecast to increase in frequency and severity. National resilience is required.

Quantifying this risk will be easier if financial institutions utilise access to relevant data on issues like coastal risk. Some of these data are becoming more freely available. Recognising the value of climate data is a trend that should continue. For a robust and resilient future, governments and the private sector should end their tango over who should pay for the information and agree that financial climate risks are best faced with eyes wide open.

Tayanah O'Donnell does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.