11
Okt
2004

Global climate change may be coming even quicker then previously believed

TODAY'S WEATHER - Oread Daily

Well, it looks worse than we thought. Global climate change may be
coming even quicker then previously believed. Atmospheric levels of carbon dioxide, the main greenhouse gas, have reportedly made a sudden jump over a two-year period. The rise cannot be explained by any corresponding increase in CO2 emissions from power stations or motor vehicles because there has been none. Some scientists believe the abrupt rise may be evidence of the climate change "feedback" mechanism, by which global warming alters the earth's natural systems, causing warming to increase even faster than before.

Feedback is what happens when a part of the output of a process or a system returns to affect the input. Positive feedback, which is what it looks like is happening, which occurs when the output goes back to add force to the input, can magnify the whole process until it takes on a "runaway" character. The fear of climate scientists is that just such a positive feedback might occur with global warming, in which the warming itself precipitates changes in the earth's natural systems, which themselves cause additional warming, which then causes further changes, and so on, in an unstoppable acceleration. This fear is well founded, because records of ancient climates deduced from cores driven deep into the polar ice show that this has happened in the past: previous episodes of warming at the end of ice ages have indeed developed a runaway character, with enormous temperature rises of as much as 10 degrees centigrade in 50 years.

The rise in the amount of carbon dioxide in the atmosphere in the last two years is unprecedented. Between 2001 and 2002 the number of parts per million of carbon dioxide rose from 371.02 to 373.10 - an increase of 2.08 over the year. Then it rose again in 2003 to 375.64 - an increase of 2.54. Rises in carbon dioxide levels have been attributed to a rise in Pacific ocean temperatures and in the past have been associated with an El-Nino. However, there was no El-Nino in these years of dramatic rise now being reported.

There are a number of possible global warming feedbacks, but the major fear associated with the current jump in CO2 is that the ability of the earth's forests and oceans to remove massive amounts of it from the atmosphere may be compromised.

Meanwhile, researchers at the University of Colorado at Boulder have found that the extent of Arctic sea ice, the floating mass of ice that covers the Arctic Ocean, is continuing its rapid decline. The latest satellite information indicates the September 2004 sea ice extent was 13.4 percent below average, a reduction in area nearly twice the size of Texas, said Mark Serreze of CU-Boulder's National Snow and Ice Data Center, or NSIDC. In 2002, the decline in arctic sea ice during September -- which traditionally marks the end of the summer melt season -- was about 15 percent, a record low, said CU- Boulder researcher Walt Meier of NSIDC. Serreze said, "This is the third year in a row with extreme ice losses, pointing to an acceleration of the downward trend." He adds, "Climate models are in general agreement that one of the strongest signals of greenhouse warming will be a loss of Arctic sea ice."

In another study at CU-Boulder, , Shari Fox Gearheard looked at the effects of climate change on Inuit communities in the Arctic region. "The timing of the climate and environmental changes observed by Inuit in Nunavut vary depending on the phenomenon, but in many cases elders and other experienced Inuit point to the last decade as a period of considerable change," Gearheard said. Nunavut is a Canadian Territory that is roughly the size of Western Europe. Gearheard said one of the most frequent observations in indigenous communities all across the circumpolar north is that the weather is more unpredictable than usual. "In the past, Inuit were able to predict the weather using traditional indicators such as clouds, winds and currents," she said. "These indicators are no longer working." Inuit elders point out that the sea ice in some places is thinner, causing dangerous travel conditions, she said. The ice forms later and breaks up earlier in the year, and the spring melt season is much shorter than before. In addition, unexpected storms have left hunting parties stranded, and harder packed snow due to recent wind changes makes it more difficult to build igloos for shelter.

And down under the effects of climate change are also well underway. "South-west Western Australia underwent a sudden climate change 25 years ago of the scale that we have only been expecting in the rest of Australia about 2040," Brian Sadler, of the Indian Ocean Climate Initiative told an international workshop on adaptation to climate change in Wellington. Annual rainfall dropped by 20 per cent and the streamflows available to Perth dropped by 40 per cent. We at first thought we were in a long dry period," Sadler said. "Only in 1996 did an international conference held in Perth identify the shift – the cause of which was still not known for certain." Sadler comments, "Climate change is coming, ready or not."

Sources: Stuff (NZ), Eurekalert, The Hindu (India), Independent (UK), Scotsman


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