Global warming's paradox: more Antarctic sea ice

The Age, April 1, 2013   

Global warming is expanding the extent of sea ice around Antarctica in winter in a paradoxical shift caused by cold plumes of summer melt water that re-freeze fast when temperatures drop, a study showed on Sunday.

An increasing summer thaw of ice on the edges of Antarctica, twinned with less than expected snowfall on the frozen continent, is also adding slightly to sea level rise in a threat to low-lying areas around the world, it said.

Climate scientists have been struggling to explain why sea ice around Antarctica has been growing, reaching a record extent in the winter of 2010, when ice on the Arctic Ocean at the other end of the planet shrank to a record low in 2012.

"Sea ice around Antarctica is increasing despite the warming global climate," said Richard Bintanja, lead author of the study at the Royal Netherlands Meteorological Institute.

"This is caused by melting of the ice sheets from below," he told Reuters of the findings in the journal Nature Geoscience.

Ice is made of fresh water and, when ice shelves on the fringes of Antarctica thaw in summer because of upwellings of warming sea water, the meltwater forms a cool layer that floats on the denser, warmer salty sea water below, the study said.

In winter, the melt water readily turns to ice because it freezes at zero degrees Celsius, above sea water at -2C (28.4F).

At a winter maximum in September, ice on the sea around Antarctica covers about 19 million sq kms (7.3 million sq miles), bigger than Antarctica's land area. It then melts away into the ocean as summer approaches.

Winds

Among other scientists, Paul Holland of the British Antarctic Survey stuck to his findings last year that a shift in winds linked to climate change was blowing a layer of melt water further out to sea and adding to winter ice.

"The possibility remains that the real increase is the sum of wind-driven and melt water-driven effects, of course. That would be my best guess, with the melt water effect being the smaller of the two," he said.

Bintanja's study also said the cool melt water layer may limit the amount of water sucked from the oceans that falls as snow on Antarctica. Cold air can hold less moisture than warm.

"Cool sea surface temperatures around Antarctica could offset projected snowfall increases in Antarctica, with implications for estimates of future sea-level rise," it said.

The U.N. panel of climate scientists has estimated that sea levels will rise by between 18 and 59 cm (7-24 inches) this century, more if thaws of Antarctica and Greenland accelerate.

The panel's main scenarios assume that Antarctica alone will make sea levels fall by between 2 and 14 cms this century because more snowfall will extract water from the sea.

But Sunday's study said that Antarctica was losing about 250 billion tonnes of ice a year - equivalent to 0.07 millimetre (0.003 inch) of sea level rise a year, Bintanja said. "Antarctic mass loss seems to be accelerating," it said.

Another study in Nature Geoscience said Antarctica's snowfall had been over-estimated by between 11 and 36.5 billion tonnes a year because of fierce winds blasting many regions.

Strong winds created conditions to "sublimate" snow, or make it pass from a frozen state to a gas without first becoming liquid, a US-led team wrote.

Link to Antarctica melt water study: (http://www.nature.com/doifinder/10.1038/ngeo1767)

Reuters

Read more: http://www.theage.com.au/environment/climate-change/global-warmings-paradox-more-antarctic-sea-ice-20130401-2h262.html#ixzz2PAZH0d5S

Global warming predictions prove accurate

Analysis of climate change modelling for past 15 years reveal accurate forecasts of rising global temperatures 

Duncan Clark 

Guardian.co.uk, Wednesday 27 March 2013

Forecasts of global temperature rises over the past 15 years have proved remarkably accurate, new analysis of scientists' modelling ofclimate change shows.

The debate around the accuracy of climate modelling and forecasting has been especially intense recently, due to suggestions that forecasts have exaggerated the warming observed so far – and therefore also the level warming that can be expected in the future. But the new research casts serious doubts on these claims, and should give a boost to confidence in scientific predictions of climate change.

The paper, published on Wednesday in the journal Nature Geoscience, explores the performance of a climate forecast based on data up to 1996 by comparing it with the actual temperatures observed since. The results show that scientists accurately predicted the warming experienced in the past decade, relative to the decade to 1996, to within a few hundredths of a degree.

The forecast, published in 1999 by Myles Allen and colleagues at Oxford University, was one of the first to combine complex computer simulations of the climate system with adjustments based on historical observations to produce both a most likely global mean warming and a range of uncertainty. It predicted that the decade ending in December 2012 would be a quarter of degree warmer than the decade ending in August 1996 – and this proved almost precisely correct.

The study is the first of its kind because reviewing a climate forecast meaningfully requires at least 15 years of observations to compare against. Assessments based on shorter periods are prone to being misleading due to natural short-term variability in the climate.

The new research also found that, compared to the forecast, the early years of the new millennium were somewhat warmer than expected. More recently the temperature has matched the forecast level very closely, but the relative slow-down in warming since the early years of the early 2000s has caused many commentators to assume that warming is now less severe than predicted. The paper shows this is not true.

Allen said: "I think it's interesting because so many people think that recent years have been unexpectedly cool. In fact, what we found was that a few years around the turn of the millennium were slightly warmer than forecast, and that temperatures have now reverted to what we were predicting back in the 1990s."

He added: "Of course, we should expect fluctuations around the overall warming trend in global mean temperatures (and even more so in Britishweather!), but the success of these early forecasts suggests the basic understanding of human-induced climate change on which they were based is supported by subsequent observations."

More angry, more often: March heatwave signals a new normal

"We can't talk about the exceptionally hot summer and early autumn without talking about climate change." 

Sophie Lewis, Postdoctoral Research Fellow at University of Melbourne and Sarah Perkins, Post Doctoral Research Fellow,  Climate Change Research Centre

The Conversation, 28 March 2013

http://theconversation.com/more-angry-more-often-march-heatwave-signals-a-new-normal-13068

Daylight hours are dwindling and our first month of autumn is ending. But in many places, March felt a lot like summer. Get used to it: looking ahead, all indications are that future summers could be just like this one, or more extreme.

Southeast Australia welcomed autumn with a persistent heat wave. For the first 12 days of autumn, temperatures were 6.9 degrees above normal across Tasmania and 6.8 degrees above normal in Victoria.

Melbourne's March record-breaking weather included nine days of temperatures of 32 degrees or above and its hottest overnight March temperature in 110 years of record keeping. Adelaide experienced ten such hot days.

The unusually warm autumn weather was part of a much larger and much longer warm spell. The last six months have been characterised by sequences of heat waves and record temperatures across the entire Australian region.

Summer was the hottest on record across all of Australia. InJanuary, Australia had its hottest month on record. The hottest day ever recorded for the entire continent occurred on January 7.

The surrounding oceans, from the Great Australian Bight through Bass Strait, also broke previous extreme temperature records. These waters exhibited the hottest sea surface temperatures on record in February.

Our exceptionally hot summer cannot be discussed simply as a catalogue of interesting record-breaking events. This summer was not normal. And we can't talk about the exceptionally hot summer and early autumn without talking about climate change.

Australian average temperatures have increased faster than the global average increase (0.8°C) and are now 0.9 degreeswarmer than a century ago.

It may not sound like much, but research shows that changes in average temperatures (even less than 1°C) can lead to huge changes in the frequency and severity of extreme climate events.

This is exactly what Australia just experienced with this sequence of heat waves, extending from November 2012 to March 2013.

Our recent research in the internationally peer-reviewed Journal of Climate shows that there has been a significant increase in the number of heat wave days for most of the country from 1951-2008. The paper describes heat waves as a period of three or more days where temperatures are excessively hot – in the top five to 10% of temperatures recorded.

This trend is greatest in eastern Australia, where both the number of heat waves and their duration has increased.

Recently, we extended the time period of the analyses to include the period from 1911 to 2011. Not surprisingly, our initial results suggest that heat waves are now occurring earlier than 100 years ago. In some places, the first heat wave of the season is occurring almost a month earlier.

Recent studies from other parts of the world have shown that many, if not most, of the recent record-breaking heat waves and extremely warm summers would have been unlikely to occur without human influence on climate change.

Although we can never say categorically whether an individual climate event, such as a heat wave, would have occurred without human-related greenhouse gas emissions, it is possible to assess how global warming has changed the likelihood of extreme events occurring.

Working with other climate scientists we investigated the probability of extreme summer heat occurring across Australia using a suite of climate model simulations representing current climate conditions. We then used a parallel suite of control experiments, in which greenhouse gases from human activities were entirely absent.

Previous studies using similar methods have found strong human contributions to the severity of extreme summer temperatures. James Hansen and other NASA scientists found a 10-fold increase in areas experiencing extremely hot summers due to global warming. Similarly, climate scientistGareth Jones and his colleagues at the UK Met Office Hadley Centre found a dominant human influence on rapidly increasing hot summers in the Northern Hemisphere.

When we ran our hot, angry summer through a large group of the latest generation of climate models it became clear that there was likely to have been a substantial human influence on our recent extreme summer heat. Our early results indicate that anthropogenic climate change more than tripled the risk of Australia's extremely hot summer occurring.

As for the future, it is now virtually certain that the frequency and severity of hot days will increase. Extremely hot seasons will worsen, with the biggest impacts of climate change being felt by Australians in summer. Spring weather will come earlier, and autumn later.

Additional global warming over the next 50 years, under a business-as-usual fossil fuel emissions scenario, is expectedto see global average temperatures increase by at least 1°C. Such a change means that our recent summer on steroids will become the norm and far worse summers will occur with greater frequency.

We already know what is causing the changes we see now. Clearly, it is time to stop talking about record-breaking heat as isolated incidents and recognise them in the context of climate change.

It's time to start preparing for more angry summers, more frequently.

Asia starts to lead way on clean energy

Tom Arup 

The Age, March 26, 2013 

Australia's neighbours in Asia - especially China - are emerging as the countries best placed to prosper from moves to cut greenhouse gas emissions, an international study has found.

In their second study of the ''low carbon competitiveness'' of the world's largest economies, multinational GE and the Climate Institute found the momentum for action on climate change had shifted from Europe and the United States towards emerging Asian economies.

The index also tracks a fall in America's ability to compete in a lower emissions world during the first few years of President Barack Obama's time in office.

Nineteen economic, energy and industrial indicators were used to calculate a country's carbon competitiveness. The updated ranking includes new data from 2008 to 2010, and indicators used include emissions growth, energy generation and the make-up of export industries.

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Australia ranks 17th out of 19 countries for low-carbon competitiveness - above only India and Saudi Arabia. It fell one place from a year ago as Indonesia leapfrogged a number of nations.

But due to a lag in data Australia's position does not take into account the national carbon price and associated programs introduced last July.

Climate Institute chief executive John Connor said that while the carbon price was working, Australia's ranking was unlikely to have improved significantly in the first year of operation because of uncertainty over the scheme's future. He said Australia's position was unlikely to significantly improve until 2014.

''I don't expect that ranking to have changed a great deal in the first year it has now come in,'' he said. ''It is actually about how we start to boost it with the [$10 billion] Clean Energy Finance Corporation and greater certainty [around the carbon price].''

The survey shows the biggest movers between 2008 and 2010 were China and Indonesia, which both moved up four spots to third and 14th respectively.

The report says the rapid rise of China is attributable to increases in clean energy investment and high-technology exports. If China had maintained its clean energy investment at 2008 levels, it would be in eighth place, the report says.

It says Asia is on track to replace Europe as the world's largest clean energy investment region, capturing more than a third of the world's investment in 2012.

Clean energy powerhouse Germany fell from second to sixth. The US fell from ninth to 11th due to declining high-tech exports and a surge in reliance on air freight.

France remained the top country on the index due to its relatively low-emission and energy-efficient economy and high-technology exports. It is followed by Japan and then China. South Korea and Britain round out the top five.

Carbon dioxide's climb speeds up

By Paul Brown

See also The Guardian - Large rise in CO2 emissions sounds climate change alarm

A few days ago came the news that atmospheric concentrations of carbon dioxide, the main greenhouse gas from human activities, had reached almost 395 parts per million, close to a significant milestone which shows how far the world is from agreeing resolute measures to tackle climate change.

The news last week that there has been a significant increase in atmospheric carbon dioxide (CO2) in the last year should have caused a ripple of fear around the world. Instead, a large stride towards the milestone of 400 parts per million (ppm) of CO2 went almost unremarked.

Yet many scientists, environmentalists and journalists who have studied climate change, campaigned to prevent it, or spent years reporting too little action by world leaders to reduce emissions, must have inwardly shuddered.

For those who understand the implications of the overwhelming scientific consensus on climate change, this is not a milestone to be passed in such a hurry and with so little attention.  If the science is right, then the human race is about to lose control of what happens to our civilization and our future.

There are those reading this who will disagree with this summary.  Some are simply in denial about what is happening. There are also campaigners who call themselves sceptics, who do not and will not accept the scientific consensus, through optimism, obstinacy, or because they have an alternative political agenda, sometimes encouraged and paid for by the fossil fuel lobby.

But what is surprising is the silence of the majority of rational human beings who accept the science but carry on as if nothing were happening.

There is admittedly room for argument about how quickly and fundamentally our lives will change. Are we merely approaching the cliff, standing on the edge, or have we already jumped?

Just to recap on where we are: the consensus the world (politicians and scientists) has reached on climate change is that the increase in global temperatures must be pegged to 2°C or below, otherwise climate change will literally get too hot to handle.

Chances shrink

Less than 10 years ago scientists came to the conclusion that to have an 80% chance of avoiding that 2°C threshold, CO2 in the atmosphere must not exceed 400 ppm.

Last week it reached 395 ppm, having risen 2.67 ppm in 2012. At that rate we will be past the 400 ppm mark in two years, with no sign at all of measures being in place to curb the rise.

In fact coal-burning world-wide, one of the chief human contributions to CO2 emissions, reached record levels in 2012 and continues to increase.

The next milestone is 450 ppm, and it is the one politicians like to mention, probably because it still seems quite a long way away. But let us remind ourselves that 450 ppm is the point at which scientists calculate we have only a 50/50 chance of keeping below a 2°C rise, and then only if carbon dioxide emissions are on a sharply downward curve by then.

So as politicians continue to fail to act, humans race towards having only a 50% chance of avoiding catastrophic climate change.

One other fact that most people conveniently forget is that the atmosphere takes up to 30 years to react to the extra CO2 that has been pumped into it. The extreme weather events occurring internationally are caused by the carbon levels of the 1980s.  Weather extremes will soon be getting a whole lot worse, whatever we do now.

Outside the climate debate and these dire predictions, economists and politicians talk another language - of the need for growth and development to feed the world's growing population.

The ostrich approach

The expansion of China, India, Brazil and two dozen or more states in Asia (and more recently Africa) is taken for granted. It is as if the stresses of climate change, water and food shortages, and the migration of peoples from arid and drowned lands, belong to another world.

An example of this double think comes from the UK. Government ministers are urging youngsters to save for their pensions, while at the same time putting back the retirement age. They are talking about this younger generation having a life expectancy close to 100.

If the scientists are right about climate change, then this is complete bunk. In 80 years' time most pension funds will have collapsed, along with the rest of civilization, and this will mainly be because today's politicians, who have their heads in the sand, have failed to act.

So why was there so little reaction to our lurch even closer to the 400 ppm milestone when so many people understand its implications?

For the scientists, part of the reason is that they have been battered into silence by the powerful and well-funded climate sceptic lobby, which has hacked into their emails, campaigned to have their grants stopped, and repeatedly questioned and obstructed their research.

Journalists have some trouble re-telling such a grim story. Each new record is incremental, and news desks do not like to depress readers too much. In the words of a (probably not apocryphal) news editor: "The punters like reading about other people's misfortunes and not their own."

Politicians calculate that they will be out of power before the worst of the effects happen, so why take difficult decisions that damage their chances of re-election?

Maybe many of the rest of us have a version of the same thoughts. We may not last long enough to see the worst of it, so why worry? The next generation may wonder why we were so irresponsible when the disastrous consequences were so perfectly clear. 

- Climate News Network
Paul Brown, one of the founders of the Climate News Network, wrote Global Warning: The Last Chance for Change in 2006. It was published in the United Kingdom by Guardian Books and A & C Black Publishers Ltd that year and in 2007 by Readers' Digest in North America.

Angry summer shaped by a shifting climate

Will Steffen, Australian Climate Commissioner,  Executive Director of the ANU Climate Change Institute at Australian National University

The Conversation, 4 March 2013

The hottest summer on record. The hottest month on record. The hottest day ever recorded for the whole of Australia. Heatwaves, bushfires, record rainfall and floods – extreme events across the land. This was the angry summer.

The Climate Commission's latest report, The Angry Summer, assesses the events of this summer and the influence of climate change on them.

Australia is a land of "droughts and flooding rains". Our history is defined by extreme events. Black Friday in 1939, Cyclone Tracy in 1974, Ash Wednesday in 1983, Black Saturday in 2009 and the terrible floods of the last few years – disasters are etched into the Australian psyche. The angry summer continues this history of extremes.

The angry summer is unusual for the record-breaking intensity and duration of the weather events. The season began with one of the driest periods on record from July to December. The heatwave in late December 2012 and the first weeks of January 2013 was unusually long and widespread. During this heat event more than 70% of Australia experienced extreme temperatures at some stage. The hot, dry weather contributed to dangerous bushfire conditions in many parts of Australia.

Later in the summer, parts of Queensland and New South Wales experienced record-breaking heavy rainfall, with daily rainfall of more than 400 millimetres in many locations. This rainfall produced severe flooding along the coast of Queensland and northern New South Wales.

All weather is influenced by climate change. The climate system is warmer and moister than it was 50 years ago, and this influences the nature, impact and intensity of extreme weather events. All of the extreme weather events of the angry summer occurred in a climate system that has vastly more heat compared to 50 years ago. That means that they were all influenced to some extent by a climate that is fundamentally shifting.

The average temperature in Australia has risen by 0.9°C since 1910. The change in average temperature has greater impacts at the margins of the temperature scale. It is highly likely that extreme hot weather will become more frequent and severe in Australia over the coming decades. Australia's angry summer shows that climate change is already adversely affecting Australians.

Looking towards the future, it is virtually certain that extreme hot weather will continue to become even more frequent and severe around the globe, including Australia, over the coming decades. It is also likely that the frequency of heavy rainfall will increase over many areas of the globe.

In Australia and around the world we need to take urgent action to reduce greenhouse gas emissions. The preventative action we take now and in the coming years will greatly influence the extent of climate change in the future, and therefore the severity of extreme weather events that our children and grandchildren will have to cope with.

This is the critical decade to get on with the job.