New research into the issue of whether atmospheric carbon dioxide has the capacity to spark an abrupt climate change has shown that past changes are more likely linked to alterations in ocean circulation unique associated with ice ages, rather than a catastrophic level of atmospheric carbon dioxide.
“There might be other mechanisms by which greenhouse gases may cause an abrupt climate change, but we know of no such mechanism from the geological record,” said David Battisti, a University of Washington atmospheric sciences professor.
The important aspect of this study to understand, however, is not that carbon dioxide cannot play a role in climate change, but rather that it is unlikely to be the cause for an abrupt shift in the climate.
David Battisti was part of a team of researchers which created a numerical climate model coupled together with an oxygen-isotope model to determine what caused climate shifts in a computer-generated episode that mimicked Heinrich events during the last ice age, which occurred from 110,000 to 10,000 years ago.
According to Wikipedia, a Heinrich event is an event when “armadas of icebergs broke off from glaciers and traversed the North Atlantic.”
The simulations showed that the sudden increase of sea-ice into the North Atlantic was directly linked to cooling of the Northern Hemisphere, and cooling of the surface of the Indian Ocean which in turn weakened the Indian monsoon and reduced rainfall over India.
Battisti makes it clear that while climate changes induced by carbon dioxide are unlikely to be abrupt, its affect is still catastrophically important.
“When you lose a keystone species, ecosystems can change very rapidly,” he said. “Smoothly retreating sea ice will cause fast warming if you live within a thousand kilometers of the ice. If warming slowly dries already semi-arid places, fires are going to be more likely.”