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‘Neglected Topic’ Winner: Climate Change

http://www.nytimes.com/2014/01/19/opinion/sunday/kristof-neglected-topic-winner-climate-change.html?_r=0

An excellent basis for discussion is the new book “The Climate Casino” by William Nordhaus, a Yale University economist. Professor Nordhaus is a moderate whose work has been cited by climate deniers, yet he concludes: “Global warming is a major threat to humans.”

Nordhaus acknowledges uncertainty but sees that as a problem: “The outcome will produce surprises, and some of them are likely to be perilous.”

For all the uncertainty, Nordhaus cites several areas of strong agreement among experts: Carbon dioxide levels in the atmosphere exceed those observed for at least the last 650,000 years; hurricanes will grow more intense; the Arctic will become ice free in summer; oceans will rise up to 23 inches by 2100 (more if there were major melting of ice sheets); and the global temperature will likely be 3.5 degrees to 7.5 degrees Fahrenheit higher in 2100 than in 1900.

A 7.5 degree difference in average temperature may not sound like much. But it’s about the differential by which Arizona is warmer than New Jersey.

Nordhaus warns that “the pace of global warming will quicken over the decades to come and climate conditions will quickly pass beyond the range of recent historical experience.”

Perhaps the greatest risk is various discontinuities and feedback loops that are difficult for climate models to account for. Melting of the Greenland ice sheet is typically predicted to add only a few inches to sea level rise by 2100, Nordhaus says. But ice dynamics are still poorly understood, and that matters a great deal. If the whole Greenland ice sheet disintegrated, that would raise sea level by 24 feet.

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