Shifting winds release ocean carbon dioxide, according to a report in ScienceDaily, 13 March 2009.
Many scientists believe the dramatic climate shift involved in ending the last ice age, usually dated as being around 17,000 years ago, occurred due a change in the earth’s orbit. Ice core records show an increase in atmospheric carbon dioxide occurred at the end of the ice age. Scientists at the Lamont-Doherty Earth Observatory, Columbia University suggest the orbital change caused westerly winds in the Southern Ocean to be displaced southwards where they caused heavy mixing in the ocean around Antarctica, which released dissolved carbon dioxide from the water into the air.
Geochemist Robert Anderson explained: “The faster the ocean turns over, the more deep water rises to the surface to release CO2. It’s this rate of overturning that regulates CO2 in the atmosphere.”
This theory was put forward two years ago by J. R. Toggweiler, a scientist at the National Oceanic and Atmospheric Administration (NOAA). The Columbia University scientists tested the theory by studying sediments from the bottom of the Southern Ocean to measure the rate of overturning. Upwelling of deep water also brings nutrients to the surface, which causes an increase in phytoplankton. The Columbia University scientists compared phytoplankton spikes in sediment cores with ice core records and “realized the added upwelling coincided with hotter temperatures in Antarctica as well as rising CO2 levels.” It seems that in the last 40 years the winds have shifted south much as they did at the end of ice age 17,000 years ago.
R. Toggweiler commented “Now I think this really starts to lock up how the CO2 changed globally. Here’s a mechanism that can explain the warming of Antarctica and the rise in CO2. It’s being forced by the north, via this change in the winds.”
However, the Columbia researchers still believe that man-made carbon dioxide is the cause of recent global warming. Robert Anderson claims the effects of the current ocean upwelling “will be dwarfed by the accelerating rate at which humans are burning fossil fuels” and said “It could well be large enough to offset some of the mitigation strategies that are being proposed to counteract rising CO2, so it should not be neglected.”
Editorial Comment: Here is another example of a natural phenomenon not caused by human activity which is causing a change in the climate, yet people want to cling onto the idea that climate change is all our fault. If natural phenomena in the past have caused changes in climate that are more drastic than recent changes, it is foolish to write them off as being dwarfed by modern human activity.
Anderson’s comment about southern ocean CO2 offsetting human strategies for counteracting rising CO2 looks like an excuse to explain the fact that anything we try to reduce the amount of CO2 is not going to work in the face of natural events that are clearly beyond our control.
Evidence News 8 April 2009
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