Researchers at Harvard and Princeton used geological indicators of sea level to conclude that during the previous interglacial period 125,000 years ago, sea level was 6.6 m (21.6 feet) higher than today. They also said that polar temperatures were 3- to 5 C (5- to 9 F) warmer than today (see abstract). The abstract concludes: “The results highlight the long-term vulnerability of ice sheets to even relatively low levels of sustained global warming.”
Study co-author Michael Oppenheimer, who is also geosciences and international affairs professor of Princeton, said that the recent findings are “something to worry about.”
“Is this the end of the world? No,” Oppenheimer said. “Does it mean there’s a premium on reducing the level of greenhouse gases as fast as reasonably possible? Yes.” (Source)
What the researchers don’t seem to realize is that they provided evidence which shows carbon dioxide is not a driver of global temperature. During the last interglacial, when temperatures were 5- to 9 F warmer than today, atmospheric levels of carbon dioxide were about 280 ppm versus about 380 ppm now. (NOAA) So why are temperatures cooler now if there is more carbon dioxide in the atmosphere?
By the way, it would take thousands of years to melt enough ice to produce the sea level rise the authors claim.
To read more about sea level history, see Sea Level Rising?
I asked Michael Oppenheimer, one of the co-authors, “how is it that temperatures were warmer in the last interglacial when carbon dioxide levels were lower if carbon dioxide is a driver of temperature?”
He replied: “Because the Earth’s orbital inclination was different, allowing more radiation to reach the northern hemisphere high latitudes, melting back ice and causing various global feedbacks.”
This shows that natural variations trump any alleged effects of carbon dioxide.