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----------------- Bulletin Message -----------------
From: MMS
To:
Date: Apr 21, 2009 3:24 PM
Subject: Arctic Meltdown is a Threat to Humanity




Arctic Meltdown is a Threat to Humanity

Editorial: Climate crunch warning

I AM shocked, truly shocked," says Katey Walter, an ecologist at the University of Alaska in Fairbanks. "I was in Siberia a few weeks ago, and I am now just back in from the field in Alaska. The permafrost is melting fast all over the Arctic, lakes are forming everywhere and methane is bubbling up out of them.
"
The permafrost is melting fast all over the Arctic, lakes are forming everywhere and methane is bubbling out of them

Back in 2006, in a paper in Nature, Walter warned that as the permafrost in Siberia melted, growing methane emissions could accelerate climate change. But even she was not expecting such a rapid change. "Lakes in Siberia are five times bigger than when I measured them in 2006. It's unprecedented. This is a global event now, and the inertia for more permafrost melt is increasing.
"

No summer ice

The dramatic changes in the Arctic Ocean have often been in the news in the past two years. There has been a huge increase in the amount of sea ice melting each summer, and some are now predicting that as early as 2030 there will be no summer ice in the Arctic at all.


Discussions about the consequences of the vanishing ice usually focus either on the opening up of new frontiers for shipping and mineral exploitation, or on the plight of polar bears, which rely on sea ice for hunting. The bigger picture has got much less attention: a warmer Arctic will change the entire planet, and some of the potential consequences are nothing short of catastrophic.


Changes in ocean currents, for instance, could disrupt the Asian monsoon, and nearly two billion people rely on those rains to grow their food. As if that wasn't bad enough, it is also possible that positive feedback from the release of methane from melting permafrost could lead to runaway warming.


Runaway warming

The danger is that if too much methane is released, the world will get hotter no matter how drastically we slash our greenhouse gas emissions. Recent studies suggest that emissions from melting permafrost could be far greater than once thought. And, although it is too early to be sure, some suspect this scenario is already starting to unfold: after remaining static for the past decade, methane levels have begun to rise again, and the source could be Arctic permafrost.


What is certain is that the Arctic is warming faster than any other place on Earth.
While the average global temperature has risen by less than 1 °C over the past three decades, there has been warming over much of the Arctic Ocean of around 3 °C. In some areas where the ice has been lost, temperatures have risen by 5 °C.


This intense warming is not confined to the Arctic Ocean. It extends south, deep into the land masses of Siberia, Alaska, Canada, Greenland and Scandinavia, and to their snowfields, ice sheets and permafrost. In 2007, the North American Arctic was more than 2 °C warmer than the average for 1951 to 1980, and parts of Siberia over 3 °C warmer. In 2008, most of Siberia was 2 °C warmer than average (see map).


Positive feedbacks

Most of this is the result of positive feedbacks (see illustration) from lost ocean ice, says David Lawrence of the National Center for Atmospheric Research in Boulder, Colorado.
His modeling studies show that during periods of rapid sea-ice loss, warming extends some 1500 kilometres inland from the ice itself. "If sea-ice continues to contract rapidly over the next several years, Arctic land warming and permafrost thaw are likely to accelerate," he says.


Changes in wind patterns may accelerate the warming even further. "Loss of summer sea ice means more heat is absorbed in the ocean, which is given back to the atmosphere in early winter, which changes the wind patterns, which favours additional sea ice loss," says James Overland, an oceanographer at the Pacific Marine Environmental Laboratory in Seattle. "The potential big deal is that we now may be having a positive feedback between atmospheric wind patterns and continued loss of sea ice.
"

Incidentally, the changing winds might also be to blame for some of the cold and snowy weather in North America and China in recent winters, Overland says. Unusual poleward flows of warm air over Siberia have displaced cold air southwards on either side.


Going global

The rapid warming in the Arctic means that a global temperature rise of 3 °C, likely this century, could translate into a 10 °C warming in the far north. Permafrost hundreds of metres deep will be at risk of thawing out.


This is where things go global. The Arctic is not just a reflective mirror that is cracking up. It is also a massive store of carbon and methane, locked into the frozen soils and buried in icy structures beneath the ocean bed.


A quarter of the land surface of the northern hemisphere contains permafrost, permanently frozen soil, water and rock. In places, deep permafrost that formed during the last ice age, when the sea level was much lower, extends far out under the ocean, beneath the seabed. Large areas of permafrost are already starting to melt, resulting in rapid erosion, buckled highways and pipelines, collapsing buildings and "drunken" forests.


Locked away

The real worry, though, is that permafrost contains organic carbon in the form of long-dead plants and animals. Some of it, including the odd mammoth, has remained frozen for tens of thousands of years. When the permafrost melts, much of this carbon is likely to be released into the atmosphere.


No one knows for sure how much carbon is locked away in permafrost, but it seems there is much more than we thought.
An international study headed by Edward Schuur of the University of Florida last year doubled previous estimates of the carbon content of permafrost to about 1600 billion tonnes - roughly a third of all the carbon in the world's soils and twice as much as is in the atmosphere.


Time bomb

Schuur estimates that 100 billion tonnes of this carbon could be released by thawing this century, based on standard scenarios. If that all emerged in the form of methane, it would have a warming effect equivalent to 270 years of carbon dioxide emissions at current levels. "It's a kind of slow-motion time bomb," he says.


One hotspot is the 40,000-year-old east Siberian permafrost region.
It alone contains 500 billion tonnes of carbon, says Philippe Ciais, co-chair of the Global Carbon Project, a research network analysing the carbon cycle. East Siberia was at times 7 °C warmer than normal during the summer of 2007, he says.


Higher temperatures mean the seasonal melting of the upper layer of soil extends down deeper than normal, melting the permafrost below.
Microbes can then break down any organic matter in the thawing layer, not only releasing carbon but also generating heat that leads to even deeper melting.
The heat produced by decomposition is yet another positive feedback that will accelerate melting, Ciais says.


Potent greenhouse gas (continue article here>>


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