Extremes in weather more likely - scientists

Deborah Smith 

The Age, April 27, 2012

See also - Climate change altering oceans,  rainfall: study

Wet areas have become wetter and dry areas drier during the past 50 years due to global warming, a study of the saltiness of the world's oceans by a team including CSIRO researchers has shown.

The intensification of rainfall and evaporation patterns, which is occurring at twice the rate predicted by climate change models, could increase the incidence and severity of extreme weather events in future.

The team's leader, Paul Durack, said the finding was important because reductions in the availability of fresh water posed more of a risk to human societies and natural ecosystems than a rise in temperature alone.

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"Changes to the global water cycle and the corresponding redistribution of rainfall will affect food availability, stability, access and utilisation," said Dr Durack, a former CSIRO researcher now at the Lawrence Livermore National Laboratory in California.

The fact that hotter air can hold more water underpinned predictions that recent warming of the globe's surface and lower atmosphere could have already strengthened the natural evaporation and precipitation cycle – increasing rainfall where it was higher than average and decreasing it where it was lower.

Initial attempts to study this "rich get richer" effect, however, were hindered by a shortage of good rainfall records on land and a lack of long-term satellite measurements. So Dr Durack and his Australian colleagues studied the oceans.

"The ocean matters to climate," said Richard Matear, a CSIRO researcher and member of the team. "It stores 97 per cent of the world's water and receives 80 per cent of all the surface rainfall." The team analysed about 1.7 million records of surface sea salinity collected worldwide between 1950 and 2000.

Their results are published in the journal Science (Ocean Salinities Reveal Strong Global Water Cycle Intensification During 1950 to 2000). They found regions near the equator and the poles, where greater rainfall keeps surface waters less salty than average, had become even fresher during the past half century. Saltier areas, such as in the centre of oceans where evaporation dominated, had become even saltier.

Brian Soden, a meteorologist at the University of Miami in the US, said the study had important implications for extreme weather.

Warmer water moving faster from the surface into the atmosphere could fuel violent storms, and floods and droughts could become more intense.

Susan Wijffels, a CSIRO researcher and team member, said a network of 35000 Argo floats throughout the world's oceans would be vital for continued observation of salinity changes.

Antarctic ice melting from warm water below: study

The Age, April 26, 2012 

Antarctica's massive ice shelves are shrinking because they are being eaten away from below by warm water, a new study finds.

That suggests that future sea levels could rise faster than many scientists have been predicting.

The western chunk of Antarctica is losing 23 feet (seven metres) of its floating ice sheet each year. Until now, scientists weren't exactly sure how it was happening and whether or how man-made global warming might be a factor. The answer, according to a study published Wednesday in the journal Nature, is that climate change plays an indirect role — but one that has larger repercussions than if Antarctic ice were merely melting from warmer air.

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Hamish Pritchard, a glaciologist at the British Antarctic Survey, said research using an ice-gazing NASA satellite showed that warmer air alone couldn't explain what was happening to Antarctica. A more detailed examination found a chain of events that explained the shrinking ice shelves.

Twenty ice shelves showed signs that they were melting from warm water below. Changes in wind currents pushed that relatively warmer water closer to and beneath the floating ice shelves. The wind change is likely caused by a combination of factors, including natural weather variation, the ozone hole and man-made greenhouse gases, Pritchard said in a phone interview.

As the floating ice shelves melt and thin, that in turn triggers snow and ice on land glaciers to slide down to the floating shelves and eventually into the sea, causing sea level rise, Pritchard said. Thicker floating ice shelves usually keep much of the land snow and ice from shedding to sea, but that's not happening now.

That whole process causes larger and faster sea level rise than simply warmer air melting snow on land-locked glaciers, Pritchard said.

"It means the ice sheets are highly sensitive to relatively subtle changes in climate through the effects of the wind," he said.

What's happening in Antarctica "may have already triggered a period of unstable glacier retreat", the study concludes. If the entire Western Antarctic Ice Sheet were to melt — something that would take many decades if not centuries — scientists have estimated it would lift global sea levels by about 16 feet (4.87 metres).

NASA chief scientist Waleed Abdalati, an expert in Earth's ice systems who wasn't involved in the research, said Pritchard's study "makes an important advance" and provides key information about how Antarctica will contribute to global sea level rise.

Another outside expert, Ted Scambos of the National Snow and Ice Data Centre, said the paper will change the way scientists think about melt in Antarctica. Seeing more warm water encircling the continent, he worries that with "a further push from the wind" newer areas could start shrinking.

Greenhouse gas emissions still on the rise, data shows

Ben Cubby

The Age, April 18, 2012 

See also - The Conversation - Australia on track to meet Kyoto Protocol target

AUSTRALIA'S greenhouse gas emissions continued to rise last year, driven by an increase in vehicle use and gases leaking from coalmines, federal government data show (see- Australia's Emissions).

The nation released 546 million tonnes more carbon dioxide than its land mass absorbed last year, not including the data from changes in land use and logging, which is recorded separately.

This is a 0.6 per cent increase on the 2010 emissions figure, still below the nation's peak in 2008.

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It keeps Australia within its international commitments, but only because it negotiated an unusually easygoing path for itself under the Kyoto Protocol. Under that deal, Australia's emissions can increase to 108 per cent of its 1990 greenhouse gas output; the present data puts the figure at 104 per cent.

The Climate Change Minister, Greg Combet, said the rise was in line with government predictions, and showed the need for a carbon price to drive more investment in renewable energy.

''This reflects the long-term trend of growth in Australia's greenhouse gas emissions since 1990 and highlights the need for action on climate change,'' Mr Combet said in a statement.

The opposition said that since Australia was on course to meet its commitments under the Kyoto Protocol, there was no need for the government's carbon price legislation, which has a baseline for Australian emissions of 578 million tonnes.

''Australians are already playing their part in reducing emissions and caring for the environment,'' the opposition climate spokesman, Greg Hunt, said.

''Slugging people with an electricity tax on top of the massive rises to date is therefore not only unfair on families but also unnecessary and ineffective.''

The new data shows that emissions equal an average of 24.3 tonnes of greenhouse gases a year for every person in Australia, a higher amount per capita than the US, which also released its national greenhouse inventory for 2010 yesterday.

The US figures show rapid growth of 3.2 per cent to just over 6.8 billion tonnes in 2010, indicating swift recovery from the slump caused by the global financial crisis.

The most recent Australian data from 2009-10, which has now been submitted to the United Nations, shows NSW remained the state that emits the most greenhouse gas, though when averaged out per person, the average Queenslander emits more than twice the amount per capita.

Total emissions for NSW came to 157.4 million tonnes of carbon dioxide or equivalent gases, just ahead of Queensland on 157.3 million and Victoria on 117.9.

Fugitive emissions from coalmines - the methane trapped underground that can leak out as coal is dug up - showed the biggest increase as more coalmining took place around the country.

''The trend increase for the quarter was largely driven by increases in emissions from fugitive emissions as a result of increased mining of black coal,'' the government's report said.

Greenhouse emissions from electricity generation dropped slightly - from 196 to 194 million tonnes, suggesting that renewable energy is making up the increase in electricity generation.

Vehicle emissions rose about 4.8 per cent, from 83 million to 87 million tonnes of carbon dioxide.

Eat less meat to prevent climate disaster, study warns

Suzanne Goldenberg,  US environment correspondent

Guardian.co.uk,  Friday 13 April 2012 

Fertilisers used in growing feed crops for cattle produce the most potent of the greenhouse gases causing climate change.

Meat eaters in developed countries will have to eat a lot less meat, cutting consumption by 50%, to avoid the worst consequences of future climate change, new research warns.

The fertilisers used in farming are responsible for a significant share of the warming that causes climate change.

A study published in Environmental Research Letters warns that drastic changes in food production and at the dinner table are needed by 2050 in order to prevent catastrophic global warming.

It's arguably the most difficult challenge in dealing with climate change: how to reduce emissions from food production while still producing enough to feed a global population projected to reach 9 billion by the middle of this century.

The findings, by Eric Davidson, director of the Woods Hole Research Centre in Massachusetts, say the developed world will have to cut fertiliser use by 50% and persuade consumers in the developed world to stop eating so much meat.

Davidson concedes it's a hard sell. Meat is a regular part of the diet in the developed world. In developing economies, such as China and India, meat consumption has risen along with prosperity.

"I think there are huge challenges in convincing people in the west to reduce portion sizes or the frequency of eating meat. That is part of our culture right now," he said.

Researchers have been paying closer attention in the past few years to the impact of agriculture on climate change, and the parallel problem of growing enough food for an expanding population. Some scientists are at work growing artificial meat which would avoid the fertilisers and manure responsible for climate change.

Nitrous oxide, released by fertilisers and animal manure, is the most potent of the greenhouse gases that cause climate change. The UN's climate body has called for deep cuts to those emissions.

Growing feed crops, for cattle and pigs, produces more of those emissions than crops that go directly into the human food chain. Eating less meat would reduce demand for fertiliser as well as reduce the amount of manure produced.

Davidson also suggests changes in current farming practice – such as growing winter ground cover crops – would help absorb nitrogen and prevent its release into the atmosphere.

In reaching his conclusion, Davidson draws on figures from the Food and Agricultural Organisation suggesting the world population will reach 8.9 billion by 2050, and that daily per capita calorie intake will also rise to 3130 calories.

Meat consumption is also projected to increase sharply to 89kg per person a year in rich countries and 37kg per person a year in the developing world.

Such a trajectory would put the world on course to more severe consequences of climate change.

Davidson is not suggesting people give up meat entirely. "The solution isn't that everyone needs to become a vegetarian or a vegan. Simply reducing portion sizes and frequency would go a long way," he said. So would switching from beef and pork, which have a high carbon foot print, to chicken or fish.

Nasa scientist: climate change is a moral issue on a par with slavery

Severin Carrell, 

Guardian.co.uk, Friday 6 April 2012 

Prof Jim Hansen to use lecture at Edinburgh International Science Festival to call for worldwide tax on all carbon emission

Averting the worst consequences of human-induced climate change is a "great moral issue" on a par with slavery, according to the leading Nasa climate scientist Prof Jim Hansen.

He argues that storing up expensive and destructive consequences for society in future is an "injustice of one generation to others".

Hansen, who will next Tuesday be awarded the prestigious Edinburgh Medal for his contribution to science, will also in his acceptance speech call for a worldwide tax on all carbon emissions.

In his lecture, Hansen will argue that the challenge facing future generations from climate change is so urgent that a flat-rate global tax is needed to force immediate cuts in fossil fuel use. Ahead of receiving the award – which has previously been given to Sir David Attenborough, the ecologist James Lovelock, and the economist Amartya Sen – Hansen told the Guardian that the latest climate models had shown the planet was on the brink of an emergency. He said humanity faces repeated natural disasters from extreme weather events which would affect large areas of the planet.

"The situation we're creating for young people and future generations is that we're handing them a climate system which is potentially out of their control," he said. "We're in an emergency: you can see what's on the horizon over the next few decades with the effects it will have on ecosystems, sea level and species extinction."

Now 70, Hansen is regarded as one of the most influential figures in climate science; the creator of one of the first global climate models, his pioneering role in warning about global warming is frequently cited by climate campaigners such as former US vice president Al Gore and in earlier science prizes, including the $1m Dan David prize. He has been arrested more than once for his role in protests against coal energy.

Hansen will argue in his lecture that current generations have an over-riding moral duty to their children and grandchildren to take immediate action. Describing this as an issue of inter-generational justice on a par with ending slavery, Hansen said: "Our parents didn't know that they were causing a problem for future generations but we can only pretend we don't know because the science is now crystal clear.

"We understand the carbon cycle: the CO2 we put in the air will stay in surface reservoirs and won't go back into the solid earth for millennia. What the Earth's history tells us is that there's a limit on how much we can put in the air without guaranteeing disastrous consequences for future generations. We cannot pretend that we did not know."

Hansen said his proposal for a global carbon tax was based on the latest analysis of CO2 levels in the atmosphere and their impact on global temperatures and weather patterns. He has co-authored a scientific paper with 17 other experts, including climate scientists, biologists and economists, which calls for an immediate 6% annual cut in CO2 emissions, and a substantial growth in global forest cover, to avoid catastrophic climate change by the end of the century.

The paper, which has passed peer review and is in the final stages of publication by the US journal Proceedings of the National Academy of Sciences, argues that a global levy on fossil fuels is the strongest tool for forcing energy firms and consumers to switch quickly to zero carbon and green energy sources. In larger countries, that would include nuclear power.

Under this proposal, the carbon levy would increase year on year, with the tax income paid directly back to the public as a dividend, shared equally, rather than put into government coffers. Because the tax would greatly increase the cost of fossil fuel energy, consumers relying on green or low carbon sources of power would benefit the most as this dividend would come on top of cheaper fuel bills. It would promote a dramatic increase in the investment and development of low-carbon energy sources and technologies.

The very rich and most profligate energy users, people with several homes, or private jets and fuel-hungry cars, would also be forced into dramatically changing their energy use. In the new paper, Hansen, director of Nasa's Goddard Institute for Space Studies, and his colleagues warn that failing to cut CO2 emissions by 6% now will mean that by 2022, the annual cuts would need to reach a more drastic level of 15% a year.

Had similar action been taken in 2005, when the Kyoto protocol on climate change came into force, the CO2 emission reductions would have been at a more manageable 3% a year. The target was to return CO2 levels in the atmosphere to 350 parts per million, down from its current level of 392ppm. The paper, the "Scientific case for avoiding dangerous climate change to protect young people and nature", also argues that the challenge is growing because of the accelerating rush to find new, harder–to-reach sources of oil, gas and coal in the deep ocean, the Arctic and from shale gas reserves.

Hansen said current attempts to limit carbon emissions, particularly the European Union's emissions trading mechanism introduced under the Kyoto protocol which restricts how much CO2 an industry can emit before it has to pay a fee for higher emissions, were "completely ineffectual". Under the global carbon tax proposal, the mechanisms for controlling fossil fuel use would be taken out of the hands of individual states influenced by energy companies, and politicians anxious about winning elections.

"It can't be fixed by individual specific changes; it has to be an across-the-board rising fee on carbon emissions," said Hansen. "We can't simply say that there's a climate problem, and leave it to the politicians. They're so clearly under the influence of the fossil fuel industry that they're coming up with cockamamie solutions which aren't solutions. That is the bottom line."

Sceptics' case melts more

Gerard Wynn 

The Age, April 6, 2012 

(The author is a Reuters Market analysts. The views expressed are his own.)

A clutch of recent studies reinforces evidence that people are causing climate change and suggests debate should now move on to a more precise understanding of its impact on humans.

The reports, published in various journals in recent weeks, add new detail to the theory of climate change and by implication cast contrarians in a more desperate light.

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To be clear: there's nothing wrong with doubting climate change; but doubts based on ignorance, a political bias or fossil fuel lobbying don't help.

The basics, well known, are that rising greenhouse gas emissions are almost certainly responsible for raising global average surface temperatures (by about 0.17 degrees Celsius a decade from 1980-2010), in turn leading to sea level rise (of about 2.3 millimetres a year from 2005-2010) and probably causing more frequent bouts of extreme heatwaves and possibly more erratic rainfall.

Vast uncertainties remain about the risk of runaway warming, and the urgency: for example, about what level of greenhouse gas emissions will cause how much sea level rise this century.

The latest studies suggest firmer evidence for a human finger print, for example showing that pollution is largely responsible for a slow cycle in sea surface temperatures in the last century.

Recent studies also cast more light on trends, for example showing that the world has seen hotter years since 1998 (previously held by some as a record); and presenting firmer forecasts for 2050.

And others show lessons from the end of the last Ice Age: for example that rises in carbon dioxide preceded (and, by implication, caused) warming; and that sea levels at one point were rising by several metres a century.

None of these are individually particular clinchers - the problem was already clear - but collectively they pin down uncertainty seized on by sceptics.

Doubt

Climate science was under a cloud after a "climategate" scandal of scientists' emails leaked in 2009 was used by sceptics to suggest that they had deliberately manipulated data - allegations rejected by several public inquiries.

And a major UN panel report made a couple of factual errors, most notably saying that all Himalayan glaciers may melt by 2035, which seemed a typographical error meant to read 2350.

In retrospect, it's incredible that these cast doubt on the scientific theory.

Like any theory, climate change is based on probabilities and observations couched in error margins and difficult to prove conclusively.

It's complicated by the poor understanding of runaway effects which could make the planet all but unrecognisable - in warming, desertification and sea level rise - over the next few centuries, distracting from a cool view.

Observations alone of rising temperatures, seas and extreme heatwaves in the past century are enough to demonstrate the problem, coupled with the lack of a plausible, alternative explanation to rising man-made carbon dioxide (CO2) emissions.

Studies

On Wednesday, scientists showed in an article published in the journal Nature that rising CO2 preceded warming at the end of the last ice age.

Previously, only Antarctic temperature data had been used, which appeared to show rising CO2 following temperature rather than the other way round.

Those older results had suggested a complex effect involving warming oceans, rising CO2 and melting ice which together tipped the world out of an Ice Age 20,000 years ago. Now the role of CO2 in driving the global climate change seems clearer.

Separately, scientists publishing in Nature estimated sea levels were rising by about 4 metres a century at one point around 15,000 years ago.

Examining the Earth's more recent history, scientists from Britain's Met Office Hadley Centre showed this week how a new understanding of the impact of pollution on cloud formation explained a slow temperature cycle previously blamed on ocean currents.

They said models could now explain an Atlantic sea surface cooling in the 1970s, and subsequent warming as clean air laws took effect. Various phases of the cycle are linked with droughts in parts of Africa and the Amazon, as well as hurricane activity.

Two weeks ago, publishing in the journal Nature Geoscience, scientists from several institutes estimated warming in the range of 1.4-3 degrees Celsius by 2050 (compared with 1961-1990 levels), a higher upper range than previously found using comprehensive, complex climate models.

Also two weeks ago, scientists from Britain's Climatic Research Unit (CRU) published updated temperature data including observations from more than 450 additional weather stations from the Arctic - made newly available by Russia and Canada.

They showed that 2005 and 2010 were the hottest years in a temperature record dating back to around 1850.

Previously CRU had said 1998 was the hottest year, leading some sceptics to claim "no global warming this century", to dismiss the urgency of the problem .

On the contrary, the basics of climate change are now understood and serious doubt is left only in the minds of those who cultivate it.

Climate science can now pin down the big uncertainties, about regional impacts, sea level rise and runaway effects, and help to put to work a response.

Reuters

Study suggests rising CO2 in the past caused global warming

Fiona Harvey,  environment correspondent, 

Guardian.co.uk,  Wednesday 4 April 2012

A paper in Nature shows how increased CO2 in the atmosphere led to warming – rather than the other way round

See also Nature - Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation

A scientific conundrum that has puzzled climate experts for years may have been solved with the publication of research showing how an increase in carbon dioxide levels in the atmosphere contributed to rising temperatures millions of years ago.

The paper, published on Wednesday in the journal Nature, has wide-ranging implications for climate science, because the question of whether a rise in carbon dioxide leads to an increase in temperature – or whether rising temperatures lead to an increase in carbon dioxide – has been seized on by climate sceptics eager to disprove a link between atmospheric carbon and global warming.

It also suggests that imminent "runaway" climate change – whereby our actions in pumping greenhouse gases into the atmosphere contribute to melting permafrost or sea changes that release stores of methane – is a real possibility.

Commenting on the findings, Prof Mark Maslin of University College London said: "[This] should put paid once and for all to the false claim that the rise in carbon dioxide was a passive response to increased global temperatures."

Prof David Beerling at the University of Sheffield, one of the universities behind the study, said: "It shows that global warming can be amplified by carbon release from thawing permafrost [and] that carbon stored in permafrost stocks today in the Arctic region is vulnerable to warming. Warming causes permafrost thaw and decomposition of organic matter releasing more greenhouse gases back into the atmosphere. This feedback loop could accelerate future warming. It means we must arrest carbon dioxide emissions released by the combustion of fossil fuels if humanity wishes to avoid triggering these sorts of feedbacks in our modern world."

For years, scientists have puzzled over graphs of the ancient temperature record, pieced together using data taken from "proxy sources" – such as ice cores and tree rings – that give an indication of what the temperature was in prehistoric times.

These sources are less accurate than today's temperature records taken using scientific instruments, and in some key respects they appeared to show that a rise in carbon dioxide followed rather than preceded warming. However, the imprecision of the proxy data meant this could not be conclusively proved or disproved.

The new paper by researchers in the US, Italy and Sheffield does not wholly answer these questions but shows that carbon dioxide may have led to a rise in temperature in the period studied. However, a rise in temperature also appeared to lead to an increase in the amount of carbon dioxide in the atmosphere. This has serious implications for global warming today because it could mean further rises in greenhouse gas concentrations will propel faster temperature rises in "runaway" global warming.

During the periods studied for the paper, the Earth emerged from an ice age and temperatures rose by about 5 C. That is similar to the temperature rise scientists predict could occur if today's global warming is not kept in check.

The researchers analysed a series of sudden and extreme global warming events called hyperthermals, occurring about 55 million years ago, linked to rising greenhouse gas concentrations and changes in the Earth's orbit, which led to a massive release of carbon into the atmosphere, ocean acidification, and a 5 degrees Celsius rise in global temperature within just a few thousand years.

Previously, researchers thought that the source of the extra carbon was the oceans, in the form of frozen methane gas in ocean-floor sediments, but from this research they conclude that the carbon came from the polar regions.

Andrew Watson, a fellow of the Royal Society and professor at the University of East Anglia, said: "The paper shows that the increase in atmospheric CO₂ was very important and drove the global temperature rise, but it also suggests that the initial trigger for the deglaciation was something different – a slight warming and associated slow-down of the Atlantic Ocean circulation. This caused carbon dioxide to start being degassed from the deep oceans, and that in turn drove the global change.

"We are making good progress in working out the complicated cause-and-effect of these past climate changes, and that gives us confidence that we understand the basics of modern climate change as well."