Study Finds Permafrost Thawing Quickly
- Study Finds Permafrost Thawing Quickly
By Larry O'Hanlon, Discovery News
Feb. 21, 2006 A new study of the Arctic permafrost forecasts that
global warming will thaw and shrink the total area of perennially
frozen ground 60 to 90 percent by 2100.
If true, it will increase the freshwater run-off into the Arctic
Ocean by 28 percent, lead to the release by soils of vast doses of
greenhouse gases, and upset ecosystems over wide areas.
"This (projection) is definitely higher than other projections, both
in area and depth," said David Lawrence, a climate modeler with the
National Oceanic and Atmospheric Administration's Climate and Global
Lawrence and Andrew Slater of the University of Colorado in Boulder
published their permafrost projection in the February issue of
Geophysical Research Letters.
Currently in the Northern Hemisphere there are about four million
square miles (10 million square kilometers) of land surface that does
not thaw, even in the summer, which comes to about 24 percent of the
land north of the equator.
Lawrence and Slater incorporated into a computer climate model the
current and projected rates of global warming, as well as the
physical parameters of freezing and thawing of the upper 11 feet (3.5
meters) of permafrost ground.
They generated a broad-brush image of what might remain of the frozen
ground by 2100. That image shows today's permafrost shrinking to
between 400,000 and about two million square miles (one to four
million square km).
Put another way, the area of permafrost lost by 2100 could match or
exceed the total land area of Australia.
Thawing such a vast swath of northern lands means those soils will
begin draining, moving more water to the sea, which raises sea levels
and could wreak havoc with global weather patterns.
It also means carbon that was frozen in the soils will be free to
move up into the atmosphere in the form of the greenhouse gases
carbon dioxide and methane, said Lawrence. This whole new source of
greenhouse gases isn't something Earth needs right now.
Other thawing consequences that are likely to reinforce warming, at
least locally, include the colonization of newly thawed ground by
"Shrubs can deepen snow drifts and change in the timing of snow
melting," said Lawrence. Generally, they speed-up the melting of
snow, he said.
Other researchers studying changes to permafrost don't see a lot to
argue about in Lawrence and Slater's projection.
"It's definitely an extreme (projection)," said Siberia permafrost
expert Larry Smith of the University of California in Los
Angeles. "But permafrost responds pretty quickly to thermal forcing.
So I don't think it's out of line."