GW : Faster Climate change expected - World news

A new report led by the U.S. Geological Survey revealed that there is a clear probability of a more rapid climate change by the end of the century, than what is suggested by previous studies.

The survey just worked towards the expansion of the 2007 findings of the United Nations Intergovernment Panel on Climate Change, and it was commissioned by the U.S. Climate Change Science Program and was issued this month. The new assessment, made from the factors such as rapid sea ice loss in the Arctic and prolonged drought in the Southwest, suggests that earlier projections may have underestimated the climatic shifts that could take place by 2100.

Some projections, already made previously in context of global warming, are on the other hand, also discarded by this new survey, viz. an abrupt release of methane from the seabed and permafrost or a shutdown of the Atlantic Ocean circulation system that brings warm water north and colder water south. These are not expected to occur till the end of this century. However, the projected amount of potential sea level rise during that period that may be greater than what other researchers have anticipated, as well as a shift to a more arid climate pattern in the Southwest by mid-century. 32 scientists contributed in this two year long duration survey.

According to the statement of Tom Armstrong, senior adviser for global change programs at USGS, the report "shows how quickly the information is advancing" on potential climate shifts. The prospect of abrupt climate change, he said, "is one of those things that keeps people up at night, because it's a low-probability but high-risk scenario. It's unlikely to happen in our lifetimes, but if it were to occur, it would be life-changing."

Report of the survey says that the pace of the melting of the ice sheet presently. will result in the increase of 4 ft. in the sea level by 2100, which was predicted to be 1.5 ft. only by that time by IPCC earlier. This is because since the last two years, the Antarctic and Greenland ice sheets are now losing an average of 48 cubic miles of ice a year, equivalent to twice the amount of ice that exists in the Alps.


The models the IPCC used did not factor in some of the dynamics that scientists now understand about ice sheet melting, said the lead author on the report's chapter on ice sheets, Konrad Steffen, who also directs the Cooperative Institute for Research in Environmental Sciences at the University of Colorado at Boulder. Apart from this, Steffen and his collaborators have identified a process of "lubrication," from which the warmer water of oceans gets in underneath coastal ice sheets and accelerates melting.

Looking at the issue of prolonged drought over the next 100 years, scientists said it is impossible to determine yet whether human activity is responsible for the drought the Southwestern United States has experienced over the past decade, but every indication suggests the region will become consistently drier in the next several decades. Some statements made by Richard Seager, a senior research scientist at Columbia University's Lamont-Doherty Earth Observatory, includes :

1) nearly all of the 24 computer models the group surveyed project the same climatic conditions for the North American Southwest, which includes Mexico.

2) If the models are correct, it will transition in the coming years and decades to a more arid climate, and that transition is already underway. Such conditions would probably include prolonged droughts lasting more than a decade.

3) scientists need to work on developing versions that can make projections on a much smaller scale. That's what the water managers out there really need. Current models don't give them the hard numbers they need.