Huge CO2 releases may have amplified global warming at end of last ice age

March 13th, 2009 - 3:44 pm ICT by ANI  

Washington, March 13 (ANI): A new research has suggested that natural releases of carbon dioxide from the Southern Ocean due to shifting wind patterns could have amplified global warming at the end of the last ice age, and could be repeated as manmade warming proceeds.

The research was conducted by a team of scientists at Columbia Universitys Lamont-Doherty Earth Observatory, US.

Many scientists think that the end of the last ice age was triggered by a change in Earths orbit that caused the northern part of the planet to warm.

This partial climate shift was accompanied by rising levels of the greenhouse gas CO2, ice core records show, which could have intensified the warming around the globe.

Now, the team from Lamont-Doherty Earth Observatory has offered one explanation for the mysterious rise in CO2.

According to them, the orbital shift triggered a southward displacement in westerly winds, which caused heavy mixing in the Southern Ocean around Antarctica, pumping dissolved carbon dioxide from the water into the air.

The faster the ocean turns over, the more deep water rises to the surface to release CO2, said lead author Robert Anderson, a geochemist at Lamont-Doherty. Its this rate of overturning that regulates CO2 in the atmosphere, he added.

In the last 40 years, the winds have shifted south much as they did 17,000 years ago, said Anderson.

If they end up venting more CO2 into the air, manmade warming underway now could be intensified.

Two years ago, J.R. Toggweiler, a scientist at the National Oceanic and Atmospheric Administration (NOAA), proposed that westerly winds in the Southern Ocean around Antarctica may have undergone a major shift at the end of the last ice age.

This shift would have raised more CO2-rich deep water to the surface, and thus amplified warming already taking place due to the earth’’s new orbital position.

Anderson and his colleagues are the first to test that theory by studying sediments from the bottom of the Southern Ocean to measure the rate of overturning.

According to the scientists, changes in the westerlies may have been triggered by two competing events in the northern hemisphere about 17,000 years ago.

The earths orbit shifted, causing more sunlight to fall in the north, partially melting the ice sheets that then covered parts of the United States, Canada and Europe.

Now I think this really starts to lock up how the CO2 changed globally, said Toggweiler. Heres a mechanism that can explain the warming of Antarctica and the rise in CO2. Its being forced by the north, via this change in the winds, he added. (ANI)

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