(Also see “Manhattan-Size Ice Island Cracks in Half.”)

The crevasse stretches 19 miles (30 kilometers) long and up to 260 feet (80 meters) wide, as shown in a picture taken by NASA’s Terra satellite in October and featured this week as a NASA Image of the Day.

Snaking across the floating tongue of the Pine Island Glacier in West Antarctica, the crack is expected to create an iceberg 350 square miles (907 square kilometers)—versus 303 square miles (785 square kilometers) for Manhattan, Brooklyn, Queens, Staten Island, and the Bronx combined, according to NASA.

As for when the iceberg might shove off, “that is very difficult to predict,” said oceanographer Eric Rignot of NASA’s Jet Propulsion Laboratory, “but in the coming months for sure.”

Glacier “Contributing Most to Sea Level”

Usually there’s nothing extraordinary about a glacier calving, said glaciologist Ted Scambos of the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado.

Glaciers that flow into the sea, like the Pine Island Glacier, go through a normal cycle in which the floating section grows, stresses mount, and an iceberg breaks off, Scambos said.

“That is nothing unusual in most cases.”

But when the pattern deviates, glaciologists take notice. In this case, the crack is forming significantly farther “upstream” than has previously been the case. That “signifies that there are changes in the ice,” he said.

When “that point of rifting starts to climb upstream, generally you see some acceleration of the glacier.” That means that the ice will flow into the ocean at a faster rate, contributing even more to sea level rise.

(Related: “Hundreds of Glaciers Melting Faster in Antarctica.”)

 Such an acceleration is of particular concern at the Pine Island Glacier, because, among Antarctic glaciers, it’s “the one that’s contributing the most to sea level rise.”

In fact, he said, ice flows from that glacier alone account for a quarter to a third of Antarctica’s total contribution to sea level rise.

“It’s moving at about three kilometers [almost two miles] per year,” Scambos said. And, he noted, “it’s been accelerating quite a bit.”

(Pictures: Antarctica Warming.)

Cracking Glacier “Really Important”

As far as sea levels are concerned, changes in the Pine Island Glacier and other West Antarctic glaciers are far more important than shifts among the continent’s other glaciers, such as East Antarctica’s Mertz Glacier—despite Mertz’s much publicized release of a Luxembourg-size iceberg in early 2010.

That’s because the “Luxembourg” iceberg came from a glacial ice tongue that had just been “sitting there,” said oceanographer Doug Martinson of Columbia University’s Lamont-Doherty Earth Observatory.

By contrast, “West Antarctica has ice streams, of which Pine Island is one. Those are fast-flowing streams of ice,” said Martinson, who specializes in polar oceans.

When ice breaks off the Pine Island Glacier, he said, more ice can flow in faster from the mountains above—ice that will eventually wind up contributing to sea level rise.

“This glacier,” NSIDC’s Scambos added, “is really important.”

Source National Geographic

The map, along with an associated animation (below) developed by NASA, reveals that ice is flowing fastest in coastal ice shelves and their tributaries, shown in this illustration in bright purple and blue. Though it’s ice that’s moving, not water, “you can imagine it like a river system,” says Bernd Scheuchl, one of the map’s creators. The fastest ice flows out to sea at a rate of a few kilometers a year. Pine Island and Thwaites Glaciers on the west coast are the most active.

The team was surprised by how far inland they found fast-moving ice, Scheuchl says. So, if Antarctica loses a great deal of its coastal ice to climate change in the coming decades, large quantities of interior ice could follow. “That’s critical knowledge for predicting future sea level rise,” NASA polar scientist Thomas Wagner said in a prepared statement.

To create this view of Antarctic ice flow, the UC Irvine researchers relied on data from satellites operated by Canada, Japan and the European Space Agency. Flow was tracked from 2007 to 2009 during a period of intense scientific monitoring of Earth’s poles that researchers all over the world had agreed to do. A report on the map was published online August 18 in Science.

Source Scientific America

An irreversible climate “tipping point” could occur within the next 20 years as a result of the release of huge quantities of organic carbon locked away as frozen plant matter in the vast permafrost region of the Arctic, scientists have found.Billions of tons of frozen leaves and roots that have lain undisturbed for thousands of years in the permanently frozen ground of the northern hemisphere are thawing out, with potentially catastrophic implications for climate change, the researchers said.

A study into the speed at which the permafrost is melting suggests that the tipping point will occur between 2020 and 2030 and will mark the point at which the Arctic turns from being a net “sink” for carbon dioxide into an overall source that will accelerate global warming, they said.

The study is the first global investigation of what will happen in a warmer world to the huge amounts of frozen plant matter that has remained undegraded in the soil since it was incorporated into the permafrost about 30,000 years ago.

It also found that by 2200 about two-thirds of the Earth’s permafrost will have melted, releasing an estimated 190 billion tons of carbon dioxide and methane into the air – about half of all the fossil fuel emissions of greenhouse gases since the start of the industrial revolution.

“Our results indicate that, as the Arctic warms up, this frozen carbon will thaw out, allowing microbial decay to resume and releasing carbon into the atmosphere,” said Kevin Schaefer of the US National Snow and Ice Data Centre in Boulder, Colorado.

“Our research shows that the release of carbon from permafrost will result in an irreversible climate tipping point in only 20 years… Once the frozen carbon thaws out and decays, there is no way to put it back into the permafrost,” Dr Schaefer said.

The Arctic has experienced some of the greatest climatic changes in the world over recent decades. Summer sea ice has melted back to record minimums, average temperatures have increased dramatically, and scientists have documented significant melting of the underground permafrost, from Alaska to eastern Siberia.

The rising temperatures have lengthened the growing season of the Arctic summer, which has increased plant growth and the consequent uptake of carbon dioxide. However, by around 2025 this will go into reverse and the thawing permafrost will release more carbon than is being taken up by the tundra growing above it, Dr Schaefer said.

“There are two important messages from this study. The first is that the melting permafrost can release huge amounts of carbon and, secondly, the process is irreversible on a human timescale and will affect our targets for reducing fossil fuel emissions,” he said.

“All our emission reduction strategies are designed to hit a target atmospheric carbon dioxide concentration corresponding to a target climate. If we do not account for carbon released from thawing permafrost, we will overshoot this target concentration and end up with a warmer climate than we want,” Dr Schaefer said.

Permanently frozen ground covers about a quarter of the northern hemisphere and starts about a metre below the surface, extending up to 500 metres. The top three metres contain most of the frozen plant matter, primarily grass roots caught up in the last ice age.

Source Independent UK

By then, Perth and the South-West would become solely reliant on water supplied from the already stressed Gnangara Mound aquifer and the Kwinana desalination plant, director Jorg Imberger said.

Even using an optimistic calculation that 35 gigalitres (35 billion litres) of rainwater would flow into the city’s dams – far greater than the 13 gigalitres last year – the dams would run dry.

“(Even) given recycled water, less water use, pumping the surface aquifer at Gnangara Mound a little bit more and hoping for rain, we’ll basically have no water left at the end of summer 2012,” Professor Imberger said.

The comments confer with the national Climate Commissioner’s first report released yesterday, which warns that water availability will be at great risk before the end of the century due to changing rainfall patterns.

WA’s South-West region was already “drying out” and all projections showed no improvement, the report by Professor Will Steffen said.

“Rainfall is the main driver of run-off, which is the direct link to water availability,” the report says.

“Hydrological modelling indicates that water availability will likely decline in south-west Western Australia.”

Perth’s dam capacity is already below 25 per cent and only 10 per cent of that is drinkable.

WA Water Commission figures show the average amount of rainfall flowing into the dams has dramatically declined since 1974:

1911 – 1974 – 338 gigalitres

1974 – 2000 – 117 gigalitres

2001 – 2005 – 92.4 gigalitres

2006 – 2010 – 57.7 gigalitres

“It’s raining less but the reduction into reservoirs has reduced even more because the vegetation is sucking up the rest (due to deforestation),” Professor Imberger said.

“Between 30-40 per cent of that reduction is due to climate change. The remainder is down to land clearing – trees are not (there to) recycle water the way they used to be.”

But a Water Corporation spokesman said it was too early too predict how much water would be left in the dams by early next year.

He said over the past 10 years the dams had averaged 100 billion litres of water per year, although last year only 13 billion litres flowed.

Rainfall flows into the dams had been getting later and later each year but it already started this year.

According to the Bureau of Meteorology, the Perth metropolitan area recorded only 59 per cent of its average annual rainfall last year.

A record hot summer brought no relief and so far this year, less than 50 millimetres of rain has fallen in Perth.

Professor Imberger said the state government’s only option to avoid running out of drinking water was to immediately bring other sources online.

That included expanding use of the Yarragadee aquifer in the South-West, doubling capacity of the second desalination plant at Binningup – due to come online by the end of the year to provide 45 gigalitres of water – to 100 gigalitres, and improving water recycling.

“Of this really serious situation nobody seems to be doing something about it,” Professor Imberger said. “Maybe they’re just hoping all this is going to go away.”

Several WA water experts have recommended tapping further into the Yarragadee aquifer to ease pressure on Gnangara Mound, which stretches from Gingin, north of Perth, to the Swan River.

The south-west aquifer stores about 1000 gigalitres and could provide three times as much drinking water as the Kwinana desalination plant, according to Professor Imberger, but the government has so far resisted using it due to opposition from locals.

Professor Imberger said planting thousands of new trees in south-west WA also would help boost future rainfalls.

The state government did not respond to inquiries about how it was managing Perth’s drinking water supply.

Source WA Today

Futher Reading – Perth’s Water Wars

New University of Washington research shows that rising sea surface temperatures in the area of the Pacific Ocean along the equator and near the International Date Line drive atmospheric circulation that has caused some of the largest shifts in Antarctic climate in recent decades.

The warmer water generates rising air that creates a large wave structure in the atmosphere called a Rossby wave train, which brings warmer temperatures to West Antarctica during winter and spring.

Antarctica is somewhat isolated by the vast Southern Ocean, but the new results “show that it is still affected by climate changes elsewhere on the planet,” said Eric Steig, a UW professor of Earth and space sciences and director of the UW Quaternary Research Center.

Steig is the corresponding author of a paper documenting the findings that is being published April 10 in the journal Nature Geoscience. The lead author is Qinghua Ding, a postdoctoral researcher in the UW Quaternary Research Center. Co-authors are David Battisti, a UW atmospheric sciences professor, and Marcel Küttel, a former UW postdoctoral researcher now working in Switzerland.

The scientists used surface and satellite temperature observations to show a strong statistical connection between warmer temperatures in Antarctica, largely brought by westerly winds associated with high pressure over the Amundsen Sea adjacent to West Antarctica, and sea surface temperatures in the central tropical Pacific Ocean.

They found a strong relationship between central Pacific sea-surface readings and Antarctic temperatures during winter months, June through August. Though not as pronounced, the effect also appeared in the spring months of September through November.

The observed circulation changes are in the form of a series of high- and low-pressure cells that follow an arcing path from the tropical Pacific to West Antarctica. That is characteristic of a textbook Rossby wave train pattern, Ding said, and the same pattern is consistently produced in climate models, at least during winter.

Using observed changes in tropical sea surface temperatures, the researchers found they could account for half to all of the observed winter temperature changes in West Antarctica, depending on which observations are used for comparison.

“This is distinct from El Niño,” Steig said. That climate phenomenon, which affects weather patterns worldwide, primarily influences sea-surface temperatures farther east in the Pacific, nearer to South America. It can be, but isn’t always, associated with strong warming in the central Pacific.

Steig noted that the influence of Rossby waves on West Antarctic climate is not a new idea, but this is the first time such waves have been shown to be associated with long-term changes in Antarctic temperature.

The findings also could have implications for understanding the causes behind the thinning of the West Antarctic Ice Sheet, which contains about 10 percent of all the ice in Antarctica.

Steig noted that the westerly winds created by the high pressure over the Amundsen Sea pushes cold water away from the edge of the ice sheet and out into the open ocean. It is then replaced by warmer water from deeper in the ocean, which is melting the seaward edge of the ice sheet from below.

The work was funded by the National Science Foundation.

Source Science Daily

The original prediction, made in 2007, gained Wieslaw Maslowski’s team a deal of criticism from some of their peers.

Now they are working with a new computer model – compiled partly in response to those criticisms – that produces a “best guess” date of 2016.

Their work was unveiled at the European Geosciences Union (EGU) annual meeting.

The new model is designed to replicate real-world interactions, or “couplings”, between the Arctic ocean, the atmosphere, the sea ice and rivers carrying freshwater into the sea.

“In the past… we were just extrapolating into the future assuming that trends might persist as we’ve seen in recent times,” said Dr Maslowski, who works at Naval Postgraduate School in Monterey, California.

“Now we’re trying to be more systematic, and we’ve developed a regional Arctic climate model that’s very similar to the global climate models participating in Intergovernmental Panel on Climate Change (IPCC) assessments,” he told BBC News.

“We can run a fully coupled model for the past and present and see what our model will predict for the future in terms of the sea ice and the Arctic climate.”

And one of the projections it comes out with is that the summer melt could lead to ice-free Arctic seas by 2016 – “plus or minus three years”.

It does not make predictions about the Greenland ice cap.

Thin evidence

One of the important ingredients of the new model is data on the thickness of ice floating on the sea.

Satellites are increasingly able to detect this, usually by measuring how far the ice sits above the sea surface – which also indicates how far the ice extends beneath.

Inclusion of this data into the team’s modelling was one of the factors causing them to retrench on the 2013 date, which raised eyebrows – and subsequently some criticism – when it emerged at a US science meeting four years ago.

Since the spectacularly pronounced melting of 2007, a greater proportion of the Arctic Ocean has been covered by thin ice that is formed in a single season and is more vulnerable to slight temperature increases than older, thicker ice.

Even taking this into account, the projected date range is earlier than other researchers believe likely.

But one peer – Dr Walt Meier from the US National Snow and Ice Data Center in Boulder, Colorado – said the behaviour of sea ice becomes less predictable as it gets thinner.

“[Maslowski's] is quite a good model, one thing it has is really high resolution, it can capture details that are lost in global climate models,” he said.

“But 2019 is only eight years away; there’s been modelling showing that [likely dates are around] 2040/50, and I’d still lean towards that.

“I’d be very surprised if it’s 2013 – I wouldn’t be totally surprised if it’s 2019.”

Crystal method

The drastic melt of 2007 remains the record loss of ice area in the satellite era, although subsequent years have still been below the long-term average.

But some researchers believe 2010′s melt was equally as notable as 2007′s, given weather conditions that were favourable to the durability of ice.

Although many climate scientists and environmental campaigners are seriously concerned about the fate of the Arctic sea ice, for other parts of society and other arms of government its degradation presents challenges and opportunities.

The Russian and Canadian governments, for example, are looking to the opportunities for mineral exploitation that will arise; while the US military has expressed concern about losing a natural defence around the country’s northern border for part of the year.

“I’m not trying to be alarmist and not trying to say ‘we know the future because we have a crystal ball’,” said Dr Maslowski.

“Basically, we’re trying to make policymakers and people who need to know about climate change in the Arctic realise there is a chance that summer sea ice could be gone by the end of the decade.

“For the national interest, the defence interest, I think it’s important to realise that 2040 is not a crystal ball prediction.”

Source BBC News

For two winters running, an Arctic chill has descended on Europe, burying that continent in snow and ice. Last year in the United States, historic blizzards afflicted the mid-Atlantic region. This winter the Deep South has endured unusual snowstorms and severe cold, and a frigid Northeast is bracing for what could shape into another major snowstorm this week.

Yet while people in Atlanta learn to shovel snow, the weather 2,000 miles to the north has been freakishly warm the past two winters. Throughout northeastern Canada and Greenland, temperatures in December ran as much as 15 to 20 degrees Fahrenheit above normal. Bays and lakes have been slow to freeze; ice fishing, hunting and trade routes have been disrupted.

Iqaluit, the capital of the remote Canadian territory of Nunavut, had to cancel its New Year’s snowmobile parade. David Ell, the deputy mayor, said that people in the region had been looking with envy at snowbound American and European cities. “People are saying, ‘That’s where all our snow is going!’ ” he said.

The immediate cause of the topsy-turvy weather is clear enough. A pattern of atmospheric circulation that tends to keep frigid air penned in the Arctic has weakened during the last two winters, allowing big tongues of cold air to descend far to the south, while masses of warmer air have moved north.

The deeper issue is whether this pattern is linked to the rapid changes that global warming is causing in the Arctic, particularly the drastic loss of sea ice. At least two prominent climate scientists have offered theories suggesting that it is. But others are doubtful, saying the recent events are unexceptional, or that more evidence over a longer period would be needed to establish a link.

Since satellites began tracking it in 1979, the ice on the Arctic Ocean’s surface in the bellwether month of September has declined by more than 30 percent. It is the most striking change in the terrain of the planet in recent decades, and a major question is whether it is starting to have an effect on broad weather patterns.

Ice reflects sunlight, and scientists say the loss of ice is causing the Arctic Ocean to absorb more heat in the summer. A handful of scientists point to that extra heat as a possible culprit in the recent harsh winters in Europe and the United States.

Their theories involve a fast-moving river of air called the jet stream that circles the Northern Hemisphere. Many winters, a strong pressure difference between the polar region and the middle latitudes channels the jet stream into a tight circle, or vortex, around the North Pole, effectively containing the frigid air at the top of the world.

“It’s like a fence,” said Michelle L’Heureux, a researcher in Camp Springs, Md., with the National Oceanic and Atmospheric Administration.

When that pressure difference diminishes, however, the jet stream weakens and meanders southward, bringing warm air into the Arctic and cold air into the midlatitudes — exactly what has happened the last couple of winters. The effect is sometimes compared to leaving a refrigerator door open, with cold air flooding the kitchen even as warm air enters the refrigerator. See * So what’s with the weather?

This has happened intermittently for many decades. Still, it is unusual for the polar vortex to weaken as much as it has lately. Last winter, one index related to the vortex hit its lowest wintertime value since record-keeping began in 1865, and it was quite low again in December.

James E. Overland, a climate scientist with NOAA in Seattle, has proposed that the extra warmth in the Arctic Ocean could be heating the atmosphere enough to make it less dense, causing the air pressure over the Arctic to be closer to that of the middle latitudes. “The added heat works against having a strong polar vortex,” he said.

But Dr. Overland acknowledges that his idea is tentative and needs further research. Many other climate scientists are not convinced, saying that a two-year span, however unusual, is not much on which to base a new theory. “We haven’t got sufficient insight to make definitive claims,” said Kevin Trenberth, head of climate analysis at the National Center for Atmospheric Research in Boulder, Colo.

Judah Cohen, director of seasonal forecasting at a company called Atmospheric and Environmental Research in Lexington, Mass., has spotted what he believes is a link between increasing snow in Siberia and the weakening of the polar vortex. In his theory, the extra snow is creating a dense, cold air mass over northern Asia in the late autumn, setting off a complex chain of cause and effect that ultimately perturbs the vortex.

Dr. Cohen said in an interview that the rising Siberian snow might, in turn, be linked to the decline of Arctic sea ice, with the open water providing extra moisture to the atmosphere — much as the Great Lakes produce heavy snows in cities like Buffalo and Syracuse. He is publishing seasonal forecasts based on his work, supported by the National Science Foundation. Those forecasts correctly predicted the recent harsh winters in the midlatitudes. But Dr. Cohen acknowledges, as does Dr. Overland, that some of his ideas are tentative and need further research.

The uncertainty about what is causing the strange winters highlights a core difficulty of climate science. While mainstream researchers are sure that greenhouse gases released by humans are warming the Earth, they acknowledge being on shakier ground in trying to predict the regional effects of that change. It is entirely possible, they say, that some regions will cool temporarily, because of disruption of the atmospheric and oceanic circulation, even as the Earth warms over all.

Bloggers who specialize in raising doubts about climate science have gleefully pointed to the recent winters in the United States and Europe as evidence that climatologists must be mistaken about a warming trend. These commentators have not been as eager to write about the strange warmth in parts of the Arctic, a region that scientists have long predicted will warm more rapidly than the planet as a whole.

Without doubt, the winter weather that began and ended 2010 was remarkable. Two of the 10 largest snowstorms in New York City history occurred last year, including the one that disrupted travel right after Christmas. The two snowstorms that fell on Washington and surrounding areas within a week in February had no known precedent in their overall impact on the region, with total accumulations of 40 inches in some places.

But the winters were not the whole story. Even without them, 2010 would have gone down as one of the strangest years in the annals of climatology, thanks in part to a weather condition known as El Niño, which dumped heat from the Pacific Ocean into the atmosphere early in the year. Later, the ocean surface cooled, a condition known as La Niña, contributing to heavy rainfall in many places.

Despite cooling from La Niña, newly compiled figures show that 2010 was among the two warmest years in the historical record. It featured a heat wave in Russia, all-time high temperatures in at least 17 countries, the hottest summer in New York City history, and devastating floods in Pakistan, China, Australia, the United States and other countries.

“It was a wild year,” said Christopher C. Burt, a weather historian for Weather Underground, an Internet site.

Still, however erratic the weather may have become, it is not obvious to most people how global warming could lead to frigid winters. Many scientists are hesitant to back such assertions, at least until they gain a better understanding of what is going on in the Arctic.

In interviews, several scientists recalled that in the decade ending in the mid-1990s, the polar vortex seemed to be strengthening, not weakening, producing mild winters in the eastern United States and western Europe.

At the time, some climate scientists wrote papers attributing that change to global warming. Newspapers, including this one, printed laments for winter lost. But soon after, the apparent trend went away, an experience that has made many researchers more cautious.

John M. Wallace, an atmospheric scientist at the University of Washington, wrote some of the earlier papers. This time around, he said, it will take a lot of evidence to convince him that a few harsh winters in London or Washington have anything to do with global warming.

“Just when you publish something and it looks like you’re seeing a connection,” Dr. Wallace said, “nature has a way of humbling us.”

Source NY Times

* Further reading on this topic from the Greenhouse Neutral Foundation 12^th of January 2010- ‘So what’s with the weather?’

Scientists have uncovered what appears to be a further dramatic increase in the leakage of methane gas that is seeping from the Arctic seabed.

Methane is about 20 times more potent than CO2 in trapping solar heat.

The findings come from measurements of carbon fluxes around the north of Russia, led by Igor Semiletov from the University of Alaska at Fairbanks.

“Methane release from the East Siberian Shelf is underway and it looks stronger than it was supposed [to be],” he said.

Professor Semiletov has been studying methane seepage in the region for the last few decades, and leads the International Siberian Shelf Study (ISSS), which has launched multiple expeditions to the Arctic Ocean.

The preliminary findings of ISSS 2009 are now being prepared for publication, he told BBC News.

Methane seepage recorded last summer was already the highest ever measured in the Arctic Ocean.

High seepage

Acting as a giant frozen depository of carbon such as CO2 and methane (often stored as compacted solid gas hydrates), Siberia’s shallow shelf areas are increasingly subjected to warming and are now giving up greater amounts of methane to the sea and to the atmosphere than recorded in the past.

This undersea permafrost was until recently considered to be stable.

But now scientists think the release of such a powerful greenhouse gas may accelerate global warming.

Higher concentrations of atmospheric methane are contributing to global temperature rise; this in turn is projected to cause further permafrost melting and the release of yet more methane in a feedback loop.

A worst-case scenario is one where the feedback passes a tipping point and billions of tonnes of methane are released suddenly, as has occurred at least once in the Earth’s past.

Such sudden releases have been linked to rapid increases in global temperatures and could have been a factor in the mass extinction of species.

According to a report by the US National Oceanic and Atmospheric Administration (Noaa), the springtime air temperature across the region in the period 2000-2007 was an average of 4C higher than during 1970-1999.

That is the fastest temperature rise on the planet, claims the university.

The recent thaw over the last decade means that some of the large reserve of carbon from organic material such as dead animals and plants in sediments is now being released into the sea and into our atmosphere.

Trapped below that is the methane hydrate now warming and leaking through holes in the defrosting sediments.

Previously it was thought much of this gas was absorbed into the sea.

But according to a recent report that Professor Semiletov and his team compiled for the environmental group WWF, the shallow depth of arctic shelves means that methane is reaching the atmosphere without reacting to become CO2 dissolved in the ocean.

Professor Semiletov’s fellow researcher aboard the Russian icebreaker that carries the ISSS team each year is Professor Orjan Gustafsson from Stockholm University in Sweden.

He said that methane measured in the atmosphere around the region is 100 times higher than normal background levels, and in some cases 1,000 times higher.

‘No alarm’

Despite the high readings, Professor Gustafsson said that so far there was no cause for alarm, and stressed that further studies were still necessary to determine the exact cause of the methane seepage.

“It is important now to understand how fast it is being released and how much is being released,” he said.

However, there is a real fear that global warming may cause Siberia’s subsea permafrost to thaw.

Some estimates put the amount of carbon trapped in shelf permafrost at 1,600 billion tonnes – roughly twice as much carbon as in the atmosphere now.

The release of this once captive carbon from destabilised ocean sediments and permafrost would have catastrophic effect on our climate and life on Earth, warn the scientists.

Source BBC News

We are entering a new era, one of rapid and often unpredictable climate change. In fact, the new climate norm is change. The 25 warmest years on record have come since 1980. And the 10 warmest years since global recordkeeping began in 1880 have come since 1998.

The effects of rising temperature are pervasive. Higher temperatures diminish crop yields, melt the mountain glaciers that feed rivers, generate more-destructive storms, increase the severity of flooding, intensify drought, cause more-frequent and destructive wildfires, and alter ecosystems everywhere. We are altering the earth’s climate, setting in motion trends we do not always understand with consequences we cannot anticipate.

Crop-withering heat waves have lowered grain harvests in key food-producing regions in recent years. One with a profoundly direct human impact was the searing heat wave that broke temperature records across Europe in 2003. The intense heat, which contributed to the world grain harvest falling short of consumption by 90 million tons, also claimed more than 52,000 lives.

There has also been a dramatic increase in the land area affected by drought in recent decades. A team of scientists at the National Center for Atmospheric Research reports that the area of the globe experiencing very dry conditions expanded from less than 15 percent in the 1970s to roughly 30 percent by 2002. The scientists attribute part of the change to a rise in temperature and part to reduced precipitation, with high temperatures becoming progressively more important during the latter part of the period. A 2009 report published by the U.S. National Academy of Sciences reinforces these findings. It concludes that if atmospheric CO2 climbs to 450–600 ppm, the world will face irreversible dry-season rainfall reductions in several regions of the world. The study likened the conditions to those of the U.S. Dust Bowl era of the 1930s.

The warming is caused by the accumulation of heat-trapping “greenhouse” gases and other pollutants in the atmosphere. Of the greenhouse gases, CO2 accounts for 63 percent of the recent warming trend, methane 18 percent, and nitrous oxide 6 percent, with several lesser gases accounting for the remaining 13 percent. Carbon dioxide comes mostly from electricity generation, heating, transportation, and industry. In contrast, human-caused methane and nitrous oxide emissions come largely from agriculture—methane from rice paddies and cattle and nitrous oxide from the use of nitrogenous fertilizer.

Atmospheric concentrations of CO2, the principal driver of climate change, have climbed from nearly 280 parts per million (ppm) when the Industrial Revolution began around 1760 to 387 ppm in 2009. The annual rise in atmospheric CO2 level, now one of the world’s most predictable environmental trends, results from emissions on a scale that is overwhelming nature’s capacity to absorb carbon. In 2008, some 7.9 billion tons of carbon were emitted from the burning of fossil fuels and 1.5 billion tons were emitted from deforestation, for a total of 9.4 billion tons. But since nature has been absorbing only about 5 billion tons per year in oceans, soils, and vegetation, nearly half of those emissions stay in the atmosphere, pushing up CO2 levels.

Methane, a potent greenhouse gas, is produced when organic matter is broken down under anaerobic conditions, including the decomposition of plant material in bogs, organic materials in landfills, or forage in a cow’s stomach. Methane can also be released with the thawing of permafrost, the frozen ground underlying the tundra that covers nearly 9 million square miles in the northern latitudes. All together, Arctic soils contain more carbon than currently resides in the atmosphere, which is a worry considering that permafrost is now melting in Alaska, northern Canada, and Siberia, creating lakes and releasing methane. Once they get under way, permafrost melting, the release of methane and CO2, and rising temperature create a self-reinforcing trend, what scientists call a “ positive feedback loop.” The risk is that the release of a massive amount of methane into the atmosphere from melting permafrost could simply overwhelm efforts to stabilize climate.

Another unsettling development is the effect of atmospheric brown clouds (ABCs) consisting of soot particles from burning coal, diesel fuel, or wood. These particles affect climate in three ways. First, by intercepting sunlight, they heat the upper atmosphere. Second, because they also reflect sunlight, they have a dimming effect, lowering the earth’s surface temperature. And third, if particles from these brown clouds are deposited on snow and ice, they darken the surface and accelerate melting. These effects are of particular concern in India and China, where a large ABC over the Tibetan Plateau is contributing to the melting of glaciers that supply the major rivers of Asia. Soot deposition causes earlier seasonal melting of mountain snow in ranges as different as the Himalayas of Asia and the Sierra Nevada of California, and it is also believed to be accelerating the melting of Arctic sea ice.

In contrast to CO2, which may remain in the atmosphere for a century or more, soot particles in ABCs are typically airborne for only a matter of weeks. Thus, once coal-fired power plants are closed or wood cooking stoves are replaced with solar cookers, atmospheric soot disappears rapidly.

If we continue with business as usual, the Intergovernmental Panel on Climate Change’s (IPCC’s) projected rise in the earth’s average temperature of 1.1–6.4 degrees Celsius (2–11 degrees Fahrenheit) during this century seems all too possible. Unfortunately, during the several years since the IPCC study was released, both global CO2 emissions and atmospheric CO2 concentrations have exceeded those in its worst-case scenario. With each passing year the chorus of urgency from the scientific community intensifies. Each new report indicates that we are running out of time. For instance, a landmark 2009 study by a team of scientists from the Massachusetts Institute of Technology concluded that the effects of climate change will be twice as severe as those they projected as recently as six years prior. Instead of a likely global temperature rise of 2.4 degrees Celsius, they now see a rise exceeding 5 degrees.

Another report, this one prepared independently as a background document for the December 2009 international climate negotiations in Copenhagen, indicated that every effort should be made to hold the temperature rise to 2 degrees Celsius above pre-industrial levels. Beyond this, dangerous climate change is considered inevitable. To hold the temperature rise to 2 degrees, the scientists note that CO2 emissions should be reduced by 60–80 percent immediately, but since this is not possible, they note that, “To limit the extent of the overshoot, emissions should peak in the near future.”

The Pew Center on Global Climate Change sponsored an analysis of some 40 scientific studies that link rising temperature with changes in ecosystems. Among the many changes reported are spring arriving nearly two weeks earlier in the United States, tree swallows nesting nine days earlier than they did 40 years ago, and a northward shift of red fox habitat that has it encroaching on the Arctic fox’s range. Inuits have been surprised by the appearance of robins, a bird they have never seen before. Indeed, there is no word in Inuit for “robin.”

Douglas Inkley, National Wildlife Federation senior science advisor, notes, “We face the prospect that the world of wildlife that we now know—and many of the places we have invested decades of work in conserving as refuges and habitats for wildlife—will cease to exist as we know them, unless we change this forecast.” Unfortunately, this observation holds true for humans as well. If we cannot quickly reduce carbon emissions, it is civilization itself that is at risk.

Adapted from Chapter 3, “Climate Change and the Energy Transition,” in Lester R. Brown, Plan B 4.0: Mobilizing to Save Civilization (New York: W.W. Norton & Company, 2009), available online at www.earth-policy.org/books/pb4.

Additional data and information sources at http://www.earth-policy.org/.