Lowy Institute Poll shows Australians’ support for climate action at its highest level in a decade


Matt McDonald, The University of Queensland

The annual Lowy Institute Poll on Australian attitudes to the world and global issues for 2018 has been released. Among a series of interesting findings, one thing is clear: support for climate action and renewable energy continue to grow.

In response to the survey’s questions on climate and energy, 59% of respondents agreed with the statement: “climate change is a serious and pressing problem. We should begin taking steps now even if this involves significant costs.”


Lowy Institute Poll 2018

This represents an increase of 5 percentage points from 2017, and a consistent increase in support for this statement over the past six years. It suggests that support for climate action in Australia is bouncing back towards its high point of 68% in the first set of Lowy Polls in 2006.




Read more:
It’s ten years since Rudd’s ‘great moral challenge’, and we have failed it


What’s more, while the federal government doggedly pursues a “technology-neutral” energy policy, Australians don’t seem to be buying it. Public support for a large-scale energy transition in Australia is even more emphatic than support for climate action.

According to the Lowy poll, which involved a nationally representative sample of 1,200 adults, 84% of Australians support the statement that “the government should focus on renewables, even if this means we may need to invest more in infrastructure to make the system more reliable”.


Lowy Institute Poll 2018

This is a staggering verdict, one that casts a shadow over Australia’s rising greenhouse emissions and the looming Commonwealth-state negotiations over the National Energy Guarantee.

Both figures suggest that most Australians are genuinely concerned about climate change, a finding consistent with the ever-growing scientific consensus.

The big question is: will Australia’s political leaders respond to this support for climate action and energy transition by putting legitimate policy in place?

It’s political

Two key impediments present themselves here, both political.

The first is Prime Minister Malcolm Turnbull’s own party. Most governments around the world that have instituted legitimate climate and energy policies have at some stage faced down their political opponents. But the biggest political opponents to Australian climate action are the government’s own internal pro-coal cabal, featuring former prime minister Tony Abbott and backbench energy committee chair Craig Kelly.

This group has fought their more moderate colleagues tooth and nail on climate and energy policy. In the process they have painted even relatively timid policies – such as the National Energy Guarantee – as extreme or fiscally irresponsible. Abbott even recently claimed he had been misled on whether the Paris targets he announced as a “definite commitment” – a 26-28% reduction of greenhouse gas emissions by 2030 relative to 2005 – were actual targets.

The second impediment to climate leadership is trepidation on the opposition benches after a bruising decade of climate policy wars. Previously, Kevin Rudd’s Labor had a field day with John Howard’s climate inaction in 2006-07, which coincided with the high point of public concern in Lowy polls.

But the party’s current leadership is all too aware that turning public concern into sustained public consensus is tricky. In the face of Abbott’s scare campaign on carbon pricing and an associated collapse in public support for climate action, Rudd infamously walked away from acting on the “greatest moral challenge”. When Rudd’s successor Julia Gillard finally legislated a carbon price, Abbott promised that the 2013 election, which he duly won, would be a “referendum on the carbon tax”.




Read more:
Two new books show there’s still no goodbye to messy climate politics


The new Lowy poll continues the trend of an inverse relationship between climate action and public concern. When the federal government is perceived as doing little (such as from 2013 to now), support for strong climate action has grown. But when the government announces or pursues genuine climate action (2007-13), support has waned.

Aligning policy with politics won’t be easy, and will take real leadership. Will we see it from Bill Shorten’s Labor if he wins office?

Security and economics: grounds for hope?

If we can’t rely on our leaders to lead – or even to respond faithfully to public opinion and scientific consensus – is there any hope for strong climate policy in Australia? There is, and it’s in some strange places.

When we think of concerns that might stymie action on issues like climate change, we might think of factors such as national security or economic growth. But in Australia and elsewhere, these concerns are arguably beginning to drive calls for climate action.

In May, a Senate inquiry into the national security implications of climate change concluded that it represents a clear and present danger to Australian security. The Lowy poll suggests that the public endorses this sentiment – Australians ranked climate change as a more pressing threat than cyber attacks, foreign interference, or the rise of China.




Read more:
Senate report: climate change is a clear and present danger to Australia’s security


While some Australian politicians are steadfast in their support for coal, despite the questionable economics, mainstream financial institutions and even energy companies like AGL are shifting away from fossil fuels. Far from economic considerations preventing climate action, as they seemed to in the 1990s, the economy might just be starting to drive that action.

The ConversationThe climate message, in short, seems to be reaching the Australian people. But will it get to those we’ve elected to represent us?

Matt McDonald, Associate Professor of International Relations, The University of Queensland

This article was originally published on The Conversation. Read the original article.

Advertisements

Antarctica has lost 3 trillion tonnes of ice in 25 years. Time is running out for the frozen continent



File 20180613 110178 4dith6.jpg?ixlib=rb 1.1
As the world prevaricates over climate action, Antarctica’s future is shrouded in uncertainty.
Hamish Pritchard/British Antarctic Survey

Steve Rintoul, CSIRO and Steven Chown, Monash University

Antarctica lost 3 trillion tonnes of ice between 1992 and 2017, according to a new analysis of satellite observations. In vulnerable West Antarctica, the annual rate of ice loss has tripled during that period, reaching 159 billion tonnes a year. Overall, enough ice has been lost from Antarctica over the past quarter-century to raise global seas by 8 millimetres.

What will Antarctica look like in the year 2070, and how will changes in Antarctica impact the rest of the globe? The answer to these questions depends on choices we make in the next decade, as outlined in our accompanying paper, also published today in Nature.




Read more:
Ocean waves and lack of sea ice can trigger Antarctic ice shelves to disintegrate


Our research contrasts two potential narratives for Antarctica over the coming half-century – a story that will play out within the lifetimes of today’s children and young adults.

While the two scenarios are necessarily speculative, two things are certain. The first is that once significant changes occur in Antarctica, we are committed to centuries of further, irreversible change on global scales. The second is that we don’t have much time – the narrative that eventually plays out will depend on choices made in the coming decade.

Change in Antarctica has global impacts

Despite being the most remote region on Earth, changes in Antarctica and the Southern Ocean will have global consequences for the planet and humanity.

For example, the rate of sea-level rise depends on the response of the Antarctic ice sheet to warming of the atmosphere and ocean, while the speed of climate change depends on how much heat and carbon dioxide is taken up by the Southern Ocean. What’s more, marine ecosystems all over the world are sustained by the nutrients exported from the Southern Ocean to lower latitudes.

From a political perspective, Antarctica and the Southern Ocean are among the largest shared spaces on Earth, regulated by a unique governance regime known as the Antarctic Treaty System. So far this regime has been successful at managing the environment and avoiding discord.

However, just as the physical and biological systems of Antarctica face challenges from rapid environmental change driven by human activities, so too does the management of the continent.

Antarctica in 2070

We considered two narratives of the next 50 years for Antarctica, each describing a plausible future based on the latest science.

In the first scenario, global greenhouse gas emissions remain unchecked, the climate continues to warm, and little policy action is taken to respond to environmental factors and human activities that affect the Antarctic.

Under this scenario, Antarctica and the Southern Ocean undergo widespread and rapid change, with global consequences. Warming of the ocean and atmosphere result in dramatic loss of major ice shelves. This causes increased loss of ice from the Antarctic ice sheet and acceleration of sea-level rise to rates not seen since the end of the last glacial period more than 10,000 years ago.

Warming, sea-ice retreat and ocean acidification significantly change marine ecosystems. And unrestricted growth in human use of Antarctica degrades the environment and results in the establishment of invasive species.

Under the high-emissions scenario, widespread changes occur by 2070 in Antarctica and the Southern Ocean, with global impacts.
Rintoul et al. 2018. Click image to enlarge.

In the second scenario, ambitious action is taken to limit greenhouse gas emissions and to establish policies that reduce human pressure on Antarctica’s environment.

Under this scenario, Antarctica in 2070 looks much like it does today. The ice shelves remain largely intact, reducing loss of ice from the Antarctic ice sheet and therefore limiting sea-level rise.

An increasingly collaborative and effective governance regime helps to alleviate human pressures on Antarctica and the Southern Ocean. Marine ecosystems remain largely intact as warming and acidification are held in check. On land, biological invasions remain rare. Antarctica’s unique invertebrates and microbes continue to flourish.

Antarctica and the Southern Ocean in 2070, under the low-emissions (left) and high-emissions (right) scenarios. Each of these systems will continue to change after 2070, with the magnitude of the change to which we are committed being generally much larger than the change realised by 2070.
Rintoul et al. 2018. Click image to enlarge.

The choice is ours

We can choose which of these trajectories we follow over the coming half-century. But the window of opportunity is closing fast.

Global warming is determined by global greenhouse emissions, which continue to grow. This will commit us to further unavoidable climate impacts, some of which will take decades or centuries to play out. Greenhouse gas emissions must peak and start falling within the coming decade if our second narrative is to stand a chance of coming true.

If our more optimistic scenario for Antarctica plays out, there is a good chance that the continent’s buttressing ice shelves will survive and that Antarctica’s contribution to sea-level rise will remain below 1 metre. A rise of 1m or more would displace millions of people and cause substantial economic hardship.

Under the more damaging of our potential scenarios, many Antarctic ice shelves will likely be lost and the Antarctic ice sheet will contribute as much as 3m of sea level rise by 2300, with an irreversible commitment of 5-15m in the coming millennia.

The ConversationWhile challenging, we can take action now to prevent Antarctica and the world from suffering out-of-control climate consequences. Success will demonstrate the power of peaceful international collaboration and show that, when it comes to the crunch, we can use scientific evidence to take decisions that are in our long-term best interest.

The choice is ours.

Steve Rintoul, Research Team Leader, Marine & Atmospheric Research, CSIRO and Steven Chown, Professor of Biological Sciences, Monash University

This article was originally published on The Conversation. Read the original article.

Ocean waves and lack of sea ice can trigger Antarctic ice shelves to disintegrate


Luke Bennetts, University of Adelaide; Rob Massom, and Vernon Squire

Large waves after the loss of sea ice can trigger Antarctic ice shelf disintegration over a period of just days, according to our new research.

With other research also published today in Nature showing that the rate of annual ice loss from the vulnerable Antarctic Peninsula has quadrupled since 1992, our study of catastrophic ice shelf collapses during that time shows how the lack of a protective buffer of sea ice can leave ice shelves, already weakened by climate warming, wide open to attack by waves.




Read more:
Antarctica has lost 3 trillion tonnes of ice in 25 years. Time is running out for the frozen continent


Antarctica is covered by an ice sheet that is several kilometres thick in places. It covers an area of 14 million square kilometres – roughly twice the size of Australia. This ice sheet holds more than 90% of the world’s ice, which is enough to raise global mean sea level by 57 metres.

As snow falls and compacts on the ice sheet, the sheet thickens and flows out towards the coast, and then onto the ocean surface. The resulting “ice shelves” (and glacier tongues) buttress three-quarters of the Antarctic coastline. Ice shelves act as a crucial braking system for fast-flowing glaciers on the land, and thus moderate the ice sheet’s contribution to sea-level rise.

In the southern summer of 2002, scientists monitoring the Antarctic Peninsula (the northernmost part of mainland Antarctica) by satellite witnessed a dramatic ice shelf disintegration that was stunning in its abruptness and scale. In just 35 days, 3,250 square km of the Larsen B Ice Shelf (twice the size of Queensland’s Fraser Island) shattered, releasing an estimated 720 billion tonnes of icebergs into the Weddell Sea.

This wasn’t the first such recorded event. In January 1995, roughly 1,500 square km of the nearby Larsen A Ice Shelf suddenly disintegrated after several decades of warming and years of gradual retreat. To the southwest, the Wilkins Ice Shelf suffered a series of strikingly similar disintegration events in 1998, 2008 and 2009 — not only in summer but also in two of the Southern Hemisphere’s coldest months, May and July.

These sudden, large-scale fracturing events removed features that had been stable for centuries – up to 11,500 years in the case of Larsen B. While ice shelf disintegrations don’t directly raise sea level (because the ice shelves are already floating), the removal of shelf ice allows the glaciers behind them to accelerate their discharge of land-based ice into the ocean – and this does raise sea levels. Previous research has shown that the removal of Larsen B caused its tributary glaciers to flow eight times faster in the year following its disintegration.




Read more:
Cold and calculating: what the two different types of ice do to sea levels


The ocean around ice shelves is typically covered by a very different (but equally important) type of ice, called sea ice. This is formed from frozen seawater and is generally no more than a few metres thick. But it stretches far out into the ocean, doubling the area of the Antarctic ice cap when at its maximum extent in winter, and varying in extent throughout the year.

The response of Antarctic sea ice to climate change and variability is complex, and differs between regions. Around the Antarctic Peninsula, in the Bellingshausen and northwestern Weddell seas, it has clearly declined in extent and annual duration since satellite monitoring began in 1979, at a similar rate to the Arctic’s rapidly receding sea ice.

The Southern Ocean is also host to the largest waves on the planet, and these waves are becoming more extreme. Our new study focuses on “long-period” swell waves (with swells that last up to about 20 seconds). These are generated by distant storms and carry huge amounts of energy across the oceans, and can potentially flex the vulnerable outer margins of ice shelves.

The earliest whalers and polar pioneers knew that sea ice can damp these waves — Sir Ernest Shackleton reported it in his iconic book South!. Sea ice thus acts as a “buffer” that protects the Antarctic coastline, and its ice shelves, from destructive ocean swells.

Strikingly, all five of the sudden major ice shelf disintegrations listed above happened during periods when sea ice was abnormally low or even absent in these regions. This means that intense swell waves crashed directly onto the vulnerable ice shelf fronts.

The straw that broke the camel’s back

The Antarctic Peninsula has experienced particularly strong climate warming (roughly 0.5℃ per decade since the late 1940s), which has caused intense surface melting on its ice shelves and exacerbated their structural weaknesses such as fractures. These destabilising processes are the underlying drivers of ice shelf collapse. But they do not explain why the observed disintegrations were so abrupt.

Our new study suggests that the trigger mechanism was swell waves flexing and working weaknesses at the shelf fronts in the absence of sea ice, to the point where they calved away the shelf fronts in the form of long, thin “sliver-bergs”. The removal of these “keystone blocks” in turn led to the catastrophic breakup of the ice shelf interior, which was weakened by years of melt.

Our research thus underlines the complex and interdependent nature of the various types of Antarctic ice – particularly the important role of sea ice in forming a protective “buffer” for shelf ice. While much of the focus so far has been on the possibility of ice shelves melting from below as the sea beneath them warms, our research suggests an important role for sea ice and ocean swells too.

The edge of an ice shelf off the Antarctic Peninsula, with floating sea ice beyond (to the left in this image).
NASA/Maria Jose Vinas

In July 2017 an immense iceberg broke away from the Larsen C Ice Shelf, just south of Larsen B, prompting fears that it could disintegrate like its neighbours.

Our research suggests that four key factors will determine whether it does: extensive flooding and fracturing across the ice shelf; reduced sea ice coverage offshore; extensive fracturing of the ice shelf front; and calving of sliver-bergs.




Read more:
Don’t worry about the huge Antarctic iceberg – worry about the glaciers behind it


If temperatures continue to rise around the Antarctic, ice shelves will become weaker and sea ice less extensive, which would imply an increased likelihood of future disintegrations.

However, the picture is not that clear-cut, as not all remaining ice shelves are likely to respond in the same way to sea ice loss and swell wave impacts. Their response will also depend on their glaciological characteristics, physical setting, and the degree and nature of surface flooding. Some ice shelves may well be capable of surviving prolonged absences of sea ice.

The ConversationIrrespective of these differences, we need to include sea ice and ocean waves in our models of ice sheet behaviour. This will be a key step towards better forecasting the fate of Antarctica’s remaining ice shelves, and how much our seas will rise in response to projected climate change over coming decades. In parallel, our new findings underline the need to better understand and model the mechanisms responsible for recent sea ice trends around Antarctica, to enable prediction of likely future change in the exposure of ice shelves to ocean swells.

Luke Bennetts, Lecturer in applied mathematics, University of Adelaide; Rob Massom, Leader, Sea Ice Group, Antarctica & the Global System program, Australian Antarctic Division and Antarctic Climate and Ecosystems CRC, and Vernon Squire, Deputy Vice-Chancellor Academic, Professor of Applied Mathematics

This article was originally published on The Conversation. Read the original article.

Why methane should be treated differently compared to long-lived greenhouse gases



File 20180607 137295 b7km0d.jpg?ixlib=rb 1.1
Livestock is a significant source of methane, a potent but short-lived greenhouse gas.
from http://www.shutterstock.com, CC BY-SA

Dave Frame, Victoria University of Wellington; Adrian Henry Macey, Victoria University of Wellington, and Myles Allen, University of Oxford

New research provides a way out of a longstanding quandary in climate policy: how best to account for the warming effects of greenhouse gases that have different atmospheric lifetimes.

Carbon dioxide is a long-lived greenhouse gas, whereas methane is comparatively short-lived. Long-lived “stock pollutants” remain in the atmosphere for centuries, increasing in concentration as long as their emissions continue and causing more and more warming. Short-lived “flow pollutants” disappear much more rapidly. As long as their emissions remain constant, their concentration and warming effect remain roughly constant as well.

Our research demonstrates a better way to reflect how different greenhouse gases affect global temperatures over time.

Cost of pollution

The difference between stock and flow pollutants is shown in the figure below. Flow pollutant emissions, for example of methane, do not persist. Emissions in period one, and the same emissions in period two, lead to a constant (or roughly constant) amount of the pollutant in the atmosphere (or river, lake, or sea).

With stock pollutants, such as carbon dioxide, concentrations of the pollutant accumulate as emissions continue.

Flow and stock pollutants over time. In the first period, one unit of each pollutant is emitted, leading to one unit of concentration. After each period, the flow pollutant decays, while the stock pollutant remains in the environment.
provided by author, CC BY

The economic theory of pollution suggests different approaches to greenhouse gases with long or short lifetimes in the atmosphere. The social cost (the cost society ought to pay) of flow pollution is constant over time, because the next unit of pollution is just replacing the last, recently decayed unit. This justifies a constant price on flow pollutants.

In the case of stock pollutants, the social cost increases with constant emissions as concentrations of the pollutant rise, and as damages rise, too. This justifies a rising price on stock pollutants.




Read more:
Cows exude lots of methane, but taxing beef won’t cut emissions


A brief history of greenhouse gas “equivalence”

In climate policy, we routinely encounter the idea of “CO₂-equivalence” between different sorts of gases, and many people treat it as accepted and unproblematic. Yet researchers have debated for decades about the adequacy of this approach. To summarise a long train of scientific papers and opinion pieces, there is no perfect or universal way to compare the effects of greenhouse gases with very different lifetimes.

This point was made in the first major climate report produced by the Intergovernmental Panel on Climate Change (IPCC) way back in 1990. Those early discussions were loaded with caveats: global warming potentials (GWP), which underpin the traditional practice of CO₂-equivalence, were introduced as “a simple approach … to illustrate the difficulties inherent in the concept”.

The problem with developing a concept is that people might use it. Worse, they might use it and ignore all the caveats that attended its development. This is, more or less, what happened with GWPs as used to create CO₂-equivalence.

The science caveats were there, and suggestions for alternatives or improvements have continued to appear in the literature. But policymakers needed something (or thought they did), and the international climate negotiations community grasped the first option that became available, although this has not been without challenges from some countries.

Better ways to compare stocks and flows

An explanation of the scientific issues, and how we address them, is contained in this article by Michelle Cain. The approach in our new paper shows that modifying the use of GWP to better account for the differences between short- and long-lived gases can better link emissions to warming.

Under current policies, stock and flow pollutants are treated as being equivalent and therefore interchangeable. This is a mistake, because if people make trade-offs between emissions reductions such that they allow stock pollutants to grow while reducing flow pollutants, they will ultimately leave a warmer world behind in the long term. Instead, we should develop policies that address methane and other flow pollutants in line with their effects.

Then the true impact of an emission on warming can be easily assessed. For countries with high methane emissions, for example from agriculture, this can make a huge difference to how their emissions are judged.

For a lot of countries, this issue is of secondary importance. But for some countries, particularly poor ones, it matters a lot. Countries with a relatively high share of methane in their emissions portfolios tend to be either middle-income countries with large agriculture sectors and high levels of renewables in their electricity mix (such as much of Latin America), or less developed countries where agricultural emissions dominate because their energy sector is small.

This is why we think the new research has some promise. We think we have a better way to conceive of multi-gas climate targets. This chimes with new possibilities in climate policy, because under the Paris Agreement countries are free to innovate in how they approach climate policy.

Improving the environmental integrity of climate policy

This could take several forms. For some countries, it may be that the new approach provides a better way of comparing different gases within a single-basket approach to greenhouse gases, as in an emissions trading scheme or taxation system. For others, it could be used to set separate but coherent emissions targets for long- and short-lived gases within a two-basket approach to climate policy. Either way, the new approach means countries can signal the centrality of carbon dioxide reductions in their policy mix, while limiting the warming effect of shorter-lived gases.

The new way of using global warming potentials demonstrably outperforms the traditional method in a range of emission scenarios, providing a much more accurate indication of how stock and flow pollutants affect global temperatures. This is especially so under climate mitigation scenarios.

Well designed policies would assist sectoral fairness within countries, too. Policies that reflect the different roles of stock and flow pollutants would give farmers and rice growers a more reasonable way to control their emissions and reduce their impact on the environment, while still acknowledging the primacy of carbon dioxide emissions in the climate change problem.

The ConversationAn ideal approach would be a policy that aimed for zero emissions of stock pollutants such as carbon dioxide and low but stable (or gently declining) emissions of flow pollutants such as methane. Achieving both goals would mean that a farm, or potentially a country, can do a better, clearer job of stopping its contribution to warming.

Dave Frame, Professor of Climate Change, Victoria University of Wellington; Adrian Henry Macey, Senior Associate, Institute for Governance and Policy Studies; Adjunct Professor, New Zealand Climate Change Research Institute. , Victoria University of Wellington, and Myles Allen, Professor of Geosystem Science, Leader of ECI Climate Research Programme, University of Oxford

This article was originally published on The Conversation. Read the original article.

Is Australia’s current drought caused by climate change? It’s complicated


Andrew King, University of Melbourne; Anna Ukkola, Australian National University, and Ben Henley, University of Melbourne

Much of southern Australia is experiencing severe drought after a very dry and warm autumn across the southern half of the continent. Australia is no stranger to drought, but this recent dry spell, and Prime Minister Malcolm Turnbull’s visit to drought-stricken parts of the country, has prompted discussion of the role of climate change in this event.

Turnbull said that farmers need to “build resilience” as rainfall “appears to be getting more variable”. This prompted former Nationals leader John Anderson to warn against “politicising” the drought by invoking climate change. This in turn was followed by speculation from numberous commentators about the links between climate change and drought.




Read more:
Australia’s 2017 environment scorecard: like a broken record, high temperatures further stress our ecosystems


So are droughts getting worse, and can they be attributed to climate change? Drought is a complex beast and can be measured in a variety of ways. Some aspects of drought are linked with climate change; others are not.

Recent warm and dry conditions have resulted in drought over parts of southern Australia.
Bureau of Meteorology

How do we measure drought?

In Australia, the Bureau of Meteorology uses rainfall deficiencies to identify regions that are under drought conditions.

Droughts are also exacerbated by low humidity, higher wind speeds, warmer temperatures, and greater amounts of sunshine. All of these factors increase water loss from soils and plants. This means that other metrics are often used to describe drought which go beyond rainfall deficiencies alone. These include the Palmer Drought Severity Index and the Standardised Precipitation Evaporation Index , for example.

This means that there are hundreds of metrics which together can provide a more detailed representation of a drought. But this also means that droughts are less well understood and described than simpler phenomena such as temperature and rainfall.

Hydrological drought, often defined by a period of low streamflow, is a response to numerous upstream processes that are unique to each river system. Hydrologists and water planners therefore often focus on directly observing and modelling runoff from water catchments.

The point here is that droughts can be multidimensional, affecting agriculture and water supplies on a wide range of spatial and temporal scales. A seasonal-scale drought that reduces soil moisture on a farm, and a decade-long drought that depletes reservoirs and groundwater supplies, can both be devastating, but in very different ways.

So is climate change affecting Australian droughts?

As we have so many ways of looking at droughts, this is a more complex question than it might first sound. Climate change may affect these drought metrics and types of drought differently, so it is hard to make general statements about the links between human-induced climate change and drought.

We know that over southern Australia, and in particular the southwest, there has been a rapid decline in winter rainfall, and that this has been linked to climate change. In the southeast there has also been a decline but the trend is harder to distinguish from the year-to-year variability.

Winter rainfall in Southwestern Australia has been in decline since the 1960s.
Bureau of Meteorology

For recent short-term droughts in southern Australia, analyses have found an increased likelihood of rainfall deficits related to human-caused climate change. Also, it has been suggested that the character of droughts is changing as a result of the human-induced warming trend.




Read more:
Recent Australian droughts may be the worst in 800 years


There is some evidence to suggest that widespread and prolonged droughts, like the Millennium Drought, are worse than other droughts in recent centuries, and may have been exacerbated by climate change. But the role of climate change in extended drought periods is difficult to discern from background climate variability. This is particularly true in Australia, which has a much more variable climate than many other parts of the world.

What does the future hold?

Future projections of drought are also difficult to constrain, as they vary across Australia and depend on the measure of drought being used. Climate models project a continuing decline in rainfall over southern Australia over the next century. Dry conditions like those seen in southeast Australia in 2006, for example, are projected to become more frequent under even low global warming targets associated with the Paris Agreement. Rainfall projections for other parts of the continent are more uncertain.




Read more:
Why 2℃ of global warming is much worse for Australia than 1.5℃


Rainfall is projected to become more extreme, with more intense rain events and fewer light rain days. This would potentially influence what future droughts look like, and how and where water moves through the land.

River flows are also projected to decline in parts of the country, with consequences for water supply to cities, ecosystems and agriculture. In the southwest, declining rainfall has led to drastic reductions in river flows since the 1970s. This trend is expected to continue. Elsewhere, changes are more uncertain but studies have suggested that the southeast could also experience declining river flows in the coming decades.

Part of the challenge of projecting future change is related to how temperature and precipitation vary together. The relationship is a double-edged sword. Increased greenhouse gas emissions mean an increased probability that low-precipitation years are also warm, suggesting that under climate change droughts may be hotter in some parts of the world. But dry conditions also often result in warmer local temperatures, increasing water loss from soils and plants.




Read more:
El Niño is here and that means droughts, but they don’t work how you might think


Droughts are tricky

Compared with other extreme weather types, it is hard to make useful statements about how climate change is altering droughts and their impacts. Protracted droughts are also rarer than many short-term natural hazards such as heatwaves. We need much longer records to reliably understand how they are changing, but these are not always available.

Compared to heatwaves and cold spells it is harder to assess the role of climate change in droughts.
National Academy of Science

There is some evidence to suggest that climate change is exacerbating drought conditions in parts of Australia, especially in the southwest and southeast. Much more work is needed to understand the intricacies of the effects of climate change on different aspects and types of drought.

The ConversationWith the uncertainties of a rapidly changing climate we need to bolster our adaptation plans so we are ready for the next big dry.

Andrew King, ARC DECRA fellow, University of Melbourne; Anna Ukkola, Research Associate, Climate Change Research Centre, Australian National University, and Ben Henley, Research Fellow in Climate and Water Resources, University of Melbourne

This article was originally published on The Conversation. Read the original article.

A bird’s eye view of New Zealand’s changing glaciers



File 20180607 137298 1hi3mur.jpg?ixlib=rb 1.1
Small aircraft carry scientists high above the Southern Alps to survey glacier changes.
Hamish McCormick/NIWA, CC BY-SA

Andrew Lorrey, National Institute of Water and Atmospheric Research; Andrew Mackintosh, Victoria University of Wellington, and Brian Anderson, Victoria University of Wellington

Every March, glacier “watchers” take to the skies to photograph snow and ice clinging to high peaks along the length of New Zealand’s Southern Alps.

This flight needs to happen on cloud-free and windless days at the end of summer before new snow paints the glaciers white, obscuring their surface features.

Each year, at the end of summer, scientists monitor glaciers along New Zealand’s Southern Alps.

Summer of records

The summer of 2017-18 was New Zealand’s warmest on record and the Tasman Sea experienced a marine heat wave, with temperatures up to six degrees above normal for several weeks.

The loss of seasonal snow cover and older ice during this extreme summer brings the issue of human-induced climate change into tight focus. The annual flights have been taking place for four decades and the data on end-of-summer snowlines provide crucial evidence.

The disappearance of snow and ice for some of New Zealand’s glaciers is clear and irreversible, at least within our lifetimes. Many glaciers we survey now will simply vanish in the coming decades.

The Franz Josef glacier advanced during the 1980s and 1990s but is now retreating.
Andrew Lorrey/NIWA, CC BY-SA

Glaciers are a beautiful part of New Zealand’s landscape, and important to tourism, but they may not be as prominent in the future. This stored component of the freshwater resource makes contributions to rivers that are used for recreation and irrigation of farm land.

Meltwater flowing from glaciers around Aoraki/Mt Cook into the Mackenzie Basin feeds important national hydroelectricity power schemes. Seasonal meltwater from glaciers can partially mitigate the impacts of summer drought. This buffering capacity may become more crucial if the eastern side of New Zealand’s mountains become drier in a changing climate.

Pioneering glacier monitoring

When Trevor Chinn began studying New Zealand’s 3,000 or so glaciers in the 1960s, he realised monitoring all of them was impossible. He searched for cost-effective ways to learn as much as he could. This resulted in comprehensive glacier mapping and new snow and ice observations when similar work was dying out elsewhere. Mapping of all of the world’s glaciers – nearly 198,000 in total – was only completed in 2012, yet Trevor had already mapped New Zealand’s ice 30 years earlier.

Octogenarian Trevor Chinn still participates in the snowline flights every year to support younger scientists.
Dave Allen/NIWA, CC BY-SA

In addition, he wanted to understand how snow and ice changed from year to year. Trevor decided to do annual glacier photographic flights, looking for the end-of-summer snowlines – a feature about half way between the terminus and the top of a glacier where hard, blue, crevassed glacier ice usually gives way to the previous winter’s snow. The altitude of this transition is an indicator of the annual health of a glacier.

It was a visionary approach that provided a powerful and unique archive of climate variability and change in a remote South Pacific region, far removed from well-known European and North American glaciers. But what was hidden at the time was that New Zealand glaciers were about to undergo significant changes.

Trevor Chinn took part in this summer’s flight and said:

This year is the worst we’ve ever seen. There was so much melt over the summer that more than half the glaciers have lost all the snow they had gained last winter, plus some from the winter before, and there’s rocks sticking out everywhere. The melt-back is phenomenal.

New insights from old observations

The Southern Alps end-of-summer snowline photo archive, produced by the National Institute of Water and Atmospheric Research, is a remarkable long-term record. Our colleagues Lauren Vargo and Huw Horgan are leading the effort to harness this resource with photogrammetry to deliver precise (metre-scale) three-dimensional models of glacier changes since 1978, building directly on Trevor Chinn’s work.

Glaciers respond to natural variability and human-induced changes, and we suspect the latter has become more dominant for our region. During the 1980s and 1990s, while glaciers were largely retreating in other parts of the world, many in New Zealand were advancing. Our recent research shows this anomaly was caused by several concentrated cooler-than-average periods, with Southern Alps air temperature linked to Tasman Sea temperatures directly upwind.

The situation changed after the early 2000s, and we postulated whether more frequent high snowlines and acceleration of ice loss would occur. Since 2010, multiple high snowline years have been observed. In 2011, the iconic Fox Glacier (Te Moeka o Tuawe) and Franz Josef Glacier (Kā Roimata o Hine Hukatere) started a dramatic retreat – losing all of the ground that they regained in the 1990s and more.

In a series of ice collapses, New Zealand’s Fox Glacier retreated by around 300 m between January 2014 and January 2015.

Looking ahead by examining the past

How New Zealand’s glaciers will respond to human-induced climate change is an important question, but the answer is complicated. A recent study suggests human-induced climate warming since about 1990 has been the largest factor driving global glacier decline. For New Zealand, which is significantly influenced by regional variability of the surrounding oceans and atmosphere, the picture is less clear.

To assess how human-induced climate influences and natural variability affect New Zealand glaciers requires the use of climate models, snowline observations and other datasets. Our research team, with support from international colleagues, are doing just that to see how Southern Alps ice will respond to a range of future scenarios.

The ConversationContinuing the snowline photograph work will allow us to better identify climate change tipping points and warning signs for our water resources – and therefore better prepare New Zealand for an uncertain future.

Andrew Lorrey, Principal Scientist & Programme Leader of Climate Observations and Processes, National Institute of Water and Atmospheric Research; Andrew Mackintosh, Professor & Director of Antarctic Research Centre, expert on glaciers and ice sheets, Victoria University of Wellington, and Brian Anderson, Senior Research Fellow, Victoria University of Wellington

This article was originally published on The Conversation. Read the original article.

Why remote Antarctica is so important in a warming world


Chris Fogwill, Keele University; Chris Turney, UNSW, and Zoe Robinson, Keele University

Ever since the ancient Greeks speculated a continent must exist in the south polar regions to balance those in the north, Antarctica has been popularly described as remote and extreme. Over the past two centuries, these factors have combined to create, in the human psyche, an almost mythical land – an idea reinforced by tales of heroism and adventure from the Edwardian golden age of “heroic exploration” and pioneers such as Robert Falcon Scott, Roald Amundsen and Ernest Shackleton.

Recent research, however, is casting new light on the importance of the southernmost continent, overturning centuries of misunderstanding and highlighting the role of Antarctica in how our planet works and the role it may play in a future, warmer world.

Heroic exploration, 1913.
wiki

What was once thought to be a largely unchanging mass of snow and ice is anything but. Antarctica holds a staggering amount of water. The three ice sheets that cover the continent contain around 70% of our planet’s fresh water, all of which we now know to be vulnerable to warming air and oceans. If all the ice sheets were to melt, Antarctica would raise global sea levels by at least 56m.

Where, when, and how quickly they might melt is a major focus of research. No one is suggesting all the ice sheets will melt over the next century but, given their size, even small losses could have global repercussions. Possible scenarios are deeply concerning: in addition to rising sea levels, meltwater would slow down the world’s ocean circulation, while shifting wind belts may affect the climate in the southern hemisphere.

In 2014, NASA reported that several major Antarctic ice streams, which hold enough water to trigger the equivalent of a one-and-a-half metre sea level rise, are now irreversibly in retreat. With more than 150m people exposed to the threat of sea level rise and sea levels now rising at a faster rate globally than any time in the past 3,000 years, these are sobering statistics for island nations and coastal cities worldwide.

An immediate and acute threat

Recent storm surges following hurricanes have demonstrated that rising sea levels are a future threat for densely populated regions such as Florida and New York. Meanwhile the threat for low-lying islands in areas such as the Pacific is immediate and acute.

Much of the continent’s ice is slowly sliding towards the sea.
R Bindschadler / wiki

Multiple factors mean that the vulnerability to global sea level rise is geographically variable and unequal, while there are also regional differences in the extremity of sea level rise itself. At present, the consensus of the IPPC 2013 report suggests a rise of between 40 and 80cm over the next century, with Antarctica only contributing around 5cm of this. Recent projections, however, suggest that Antarctic contributions may be up to ten times higher.

Studies also suggest that in a world 1.5-2°C warmer than today we will be locked into millennia of irreversible sea level rise, due to the slow response time of the Antarctic ice sheets to atmospheric and ocean warming.

We may already be living in such a world. Recent evidence shows global temperatures are close to 1.5°C warmer than pre-industrial times and, after the COP23 meeting in Bonn in November, it is apparent that keeping temperature rise within 2°C is unlikely.

So we now need to reconsider future sea level projections given the potential global impact from Antarctica. Given that 93% of the heat from anthropogenic global warming has gone into the ocean, and these warming ocean waters are now meeting the floating margins of the Antarctic ice sheet, the potential for rapid ice sheet melt in a 2°C world is high.

In polar regions, surface temperatures are projected to rise twice as fast as the global average, due to a phenomenon known as polar amplification. However, there is still hope to avoid this sword of Damocles, as studies suggest that a major reduction in greenhouse gases over the next decade would mean that irreversible sea level rise could be avoided. It is therefore crucial to reduce CO₂ levels now for the benefit of future generations, or adapt to a world in which more of our shorelines are significantly redrawn.

This is both a scientific and societal issue. We have choices: technological innovations are providing new ways to reduce CO₂ emissions, and offer the reality of a low-carbon future. This may help minimise sea level rise from Antarctica and make mitigation a viable possibility.

The ConversationGiven what rising sea levels could mean for human societies across the world, we must maintain our longstanding view of Antarctica as the most remote and isolated continent.

Chris Fogwill, Professor of Glaciology and Palaeoclimatology, Keele University; Chris Turney, Professor of Earth Sciences and Climate Change, UNSW, and Zoe Robinson, Reader in Physical Geography and Sustainability/Director of Education for Sustainability, Keele University

This article was originally published on The Conversation. Read the original article.