CROSSING A CLIMATE THRESHHOLD
THE FUTURE: An unbalanced climate?
"The Earth's climate system is an ornery beast which overreacts to even small nudges" --Wallace BroeckerWill the present greenhouse warming trigger the release of methane? "We simply don't know," says James Kennett, a paleoceanographer at the University of California, Santa Barbara, "but the concern is realistic." Luckily, our world has a safety valve that was absent in the Paleocene: glaciers. If methane starts to bubble out of ocean sediments and warms the atmosphere, glaciers will begin to melt. The additional water in the ocean will increase the pressure on the sediments and prevent them from releasing more methane, says U.S. Geological Survey geochemist Keith Kvenvolden.The Paleocene hot spell, says Zachos, should serve as a reminder of the unpredictable nature of climate. Wallace Broecker, a paleoclimatologist at Columbia University, wrote last year in Science that "The paleoclimate record shouts out to us that, far from being self-stabilizing, the Earth's climate system is an ornery beast which overreacts to even small nudges." And humans have already given the climate a substantial nudge.
