Sunday, September 23, 2007

MORE ON THE "MAMMOTH DUNG" FANTASY

Previous comment here. Popular summary of recent research followed by journal abstract below:

Permafrost melting not a problem

"A re-examination of projected melting of Arctic permafrost from global warming indicates that massive releases of methane from permafrost degradation are unlikely in this century. During the 20th century, humans' increasing greenhouse gas emissions have made Arctic regions warmer, causing permafrost to melt. Model projections indicate that, as the climate warms, permafrost will continue melting and methane bound in frozen sediments could escape to the atmosphere. Because methane is also a greenhouse gas, this would exacerbate global warming. One permafrost model, presented in late 2005, indicated that near-surface Arctic permafrost will completely degrade during the 21st century.

Now, Delisle has critically reviewed this model, finding it to lack necessary initial parameters. He offers an alternative model designed to have a more complete mathematical formulation of the physical processes in permafrost. It projects that surface permafrost will persist in areas north of 70§N latitude. Permafrost will also endure at depth between 60§N and 70§N. Delisle notes that ice-core analyses previously made by other scientists indicate minimal release of methane during warm periods in the last 9,000 years. Based on the new model and the ice-core findings, he concludes that scenarios calling for massive releases of methane in the near future from degrading permafrost are questionable."

Source

Journal abstract:

Near-surface permafrost degradation: How severe during the 21st century?

By G. Delisle

A previously presented model on nearly complete near-surface permafrost degradation in the Arctic during the 21st century is critically reviewed. An alternative model with a more complete mathematical formulation of the physical processes acting in permafrost terrain is presented, which suggests that permafrost will mostly prevail in this century in areas north of 70øN. Furthermore, permafrost will survive at depth in most areas between 60ø to 70øN. Based on paleoclimatic data and in consequence of this study, it is suggested that scenarios calling for massive release of methane in the near future from degrading permafrost are questionable.

Source

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