Tundra test stuns scientists Carbon dioxide could be dumped into atmosphere Raises spectre of accelerated global warming PETER CALAMAI SCIENCE REPORTER Sep. 23, 2004 http://www.thestar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_Type1&c=Article&cid=1095891011063
OTTAWA÷Dramatic results made public today from a unique 20-year American experiment are raising the spectre of runaway warming above the Arctic tundra that would accelerate global climate change. The findings, if confirmed with additional studies, could also doom Canada's Kyoto plan targets for reducing emissions of carbon dioxide, the leading greenhouse gas. This double whammy arises because U.S. researchers discovered climate warming might trigger conditions where tundra decomposition will dump carbon dioxide into the atmosphere faster than it's soaked up by accelerated plant growth. This extra carbon dioxide could trigger a "positive feedback," speeding up the rate of global warming even more, warns a study published today in Nature, the influential British research journal. The results also add extra urgency to a planned November meeting of ministers from Canada and seven other circumpolar countries, called to approve a program to tackle the impact of climate change in the Arctic. More than 40 per cent of the world's Arctic vegetation region lies in Canada. Until now, most studies projected that the tundra would be a carbon dioxide "sink" rather than a source under climate change. Meeting Canada's Kyoto targets depends on getting credit for net reduction of carbon dioxide in the tundra. But if all the carbon currently stored as peat, moss and other ancient vegetation in the top metre of tundra decomposed, that would boost global atmospheric levels of carbon dioxide by roughly 25 per cent, says Paul Grogan, a Queen's University expert in northern ecosystems. "This study raises some big questions," said Grogan, holder of a Canada Research Chair who co-authored a commentary about the findings in Nature. Grogan and the study's lead author, Michelle Mack, both emphasized that the experiments carried out at a long-term ecological research site in Alaska looked at just one key aspect ÷ the impact of more nutrients in the soil ÷ in the complex cycling of carbon between the atmosphere and the earth. The findings might not hold true in different northern regions, like the immense boreal bogs or the so-called polar desert. And other environmental influences need to be included in any calculation, such as permafrost thawing and warmer soil, the researchers say. "There is a lot of diversity in tundra," cautioned Mack, a professor in the University of Florida's botany department who carried out the field work as a researcher at the University of Alaska in Fairbanks. Despite such cautions, the experimental findings are so dramatic and unexpected that the study has already aroused great interest among Arctic ecologists and climate-change scientists. "These results challenge some of our assumptions that more vegetation and trees mean that you're automatically storing net carbon, even if only temporarily," says Tim Moore, a McGill University geography professor investigating the carbon cycle in a bog near Ottawa. Mack found that the artificially fertilized tundra plots near Toolik Lake in Alaska suffered a net loss of two kilograms of carbon per square metre in the 20 years between 2000 and 1981, when the experiment began. Most of the loss took place in layers deeper than five centimetres, and had been missed previously because measurements went no deeper than the root level. "This was probably the most surprising thing that I and my colleagues had seen for a long time," Mack recalled. The addition of nitrogen and phosphorus fertilizer mimicked nutrient conditions expected under the pronounced warming projected in the Arctic by climate-change models. Microbes become more active as soil warms and digest organic matter, transforming carbon to carbon dioxide and freeing up nutrients like nitrogen and phosphorous that spur plant growth. The U.S. experiments found that plant growth doubled atop the tundra, with a knee-high species of woody shrub replacing low sedges. But the extra carbon locked up in this new vegetation was outweighed by carbon released through accelerated decomposition and leaching in the tundra. "These are the first people to look at what happens by digging deeper in the soil," said Grogan. The Queen's professor has just launched a similar research project at Daring Lake, some 480 kilometres north of Yellowknife in the Northwest Territories. Unlike the U.S. experiment, the Canadians are varying the concentrations of fertilizer applied, and using greenhouses to raise temperatures and snow fences to manipulate the snow cover. Grogan estimated it would take at least five years to produce the first results. Canada lags far behind the U.S. and other circumpolar countries in almost every area of Arctic science because low federal funding over the last two decades has stymied older northern researchers and discouraged new scientists from entering the field. <><><><><><> RESEARCHERS FIND FROZEN NORTH MAY ACCELERATE CLIMATE CHANGE October 07, 2004 - (date of web publication) http://www.gsfc.nasa.gov/topstory/2004/0929frozenclimate.html NASA-funded researchers have found that despite their sub-zero temperatures, a warming north may add more carbon to the atmosphere from soil, accelerating climate warming further. [more] _______________________________________________ Biofuel mailing list [EMAIL PROTECTED] http://wwia.org/mailman/listinfo.cgi/biofuel Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuel archives at Infoarchive.net (searchable): http://infoarchive.net/sgroup/biofuel/
