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Here's a good one for you skippy! no humans needed.
Gore's says a one degree rise (C) will raise ocean levels 20 feet. Well, this show in the past a temp rise of about 12 (C) only caused a 16 foot rise.
New Cause for Past Global Warming Revealed by Massive Modeling Project
July 16, 2009
BOULDER—By simulating 8,000 years of climate with unprecedented detail and accuracy, a team led by scientists from the University of Wisconsin–Madison and the National Center for Atmospheric Research (NCAR) has found a new explanation for the last major period of global warming, which occurred about 14,500 years ago.
In a period called the Bølling-Allerød warming, global sea level rose by 16 feet and temperatures in Greenland soared by up to 27 degrees Fahrenheit over several hundred years. The new study shows how increased carbon dioxide, strengthening ocean currents, and a release of ocean-stored heat could have combined to trigger the warming.
Findings from the experiment appear in the July 17 issue of Science. The study was funded by NCAR's sponsor, the National Science Foundation (NSF), and by the U.S. Department of Energy (DOE). Simulations were conducted on the Community Climate System Model (CCSM), which is a collaborative effort based at NCAR and supported primarily by NSF and DOE.
The study examined the period from 22,000 to 14,000 years ago, as Earth emerged in fits and starts from the extreme cold of the last ice age. Temperatures rose from about 21,000 to 19,000 years ago, then cooled again after glacial meltwater weakened the Atlantic Ocean's warming "conveyor belt," also called the thermohaline circulation.
One mystery the scientists hoped to solve was why global warming resumed so abruptly and strongly during the Bølling-Allerød period, about 14,500 years ago. Previous studies using simpler models had speculated that a sudden shift in the Atlantic Ocean conveyor belt might have caused the Bølling-Allerød warming. However, the new work with the CCSM suggests that three factors each contributed about a third of the warming:
* an increase of about 40 parts per million in atmospheric carbon dioxide
* a strengthening of the Atlantic Ocean's conveyor belt circulation
* the release of heat stored in the ocean over thousands of years
"Once the glacial melt stopped, the enormous subsurface heat that had accumulated for 3,000 years erupted like a volcano and popped out over decades," says Liu. "This huge heat flux melted the sea ice and warmed up Greenland."