(CNSNEws.com) - Which is it--6 feet or 3.5 feet?
Last week, White House science czar John Holdren told members of the House Select Committee on Energy Independence and Global Warming that changes in global temperatures could mean a rise in sea levels of 6 feet or more in a century.
But Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration, told the same committee on the same day that changes in global temperatures could mean a rise in sea levels of up to 3.5 feet in this century.
Holdren and Lubchenco were the only two witnesses called to testify at the Global Warming committee's Dec. 2 hearing, which was titled "The State of Climate Science."
In his written testimony Holdren, whose official title is “Assistant to the President for Science and Technology and Director of the Office of Science and Technology Policy,” wrote that changes in temperature from global warming could bring about what he called “tipping points” in the climate system--which he defined as “thresholds beyond which a small additional increase in average temperature or some associated climate variable results in major changes to the affected system.”
Examples of “tipping points” that he cited include:
--“the complete disappearance of Arctic sea ice in summer, leading to drastic changes in ocean circulation and climate patterns across the whole Northern Hemisphere;
--“drastic acceleration of the rate of ice loss from the Greenland and Antarctic ice sheets, driving rates of sea-level increase that could reach 6 feet per century or more; [emphasis added]
-- “ocean acidification from CO2 absorption reaching a level that causes massive disruption in ocean food webs; and a flood of carbon dioxide and methane from warming tundra and thawing permafrost, accelerating the onset of all of the other impacts of concern.”
However, on the same day, Dr. Lubchenco told members of the same House committee that the maximum sea level rise would be 3.5 feet.
“The amount of sea level rise likely to be experienced during this century depends mainly on the expansion of ocean volume due to warming and the melting of glaciers and polar ice sheets,” the NOAA chief said [emphasis added].
“Complex processes control discharges from polar ices sheets and some are already contributing to sea level rise. In addition regional affects from changes in ocean circulation and geological and human processes that affect the elevation of the land above sea-level can either add to or subtract from the global mean sea level rise projected to be as high as 3.5 feet in some scenarios of increasing heat-trapping greenhouse gases.”
Calls by CNSNews.com to Holdren’s office and to the National Oceanic and Atmospheric Administration for explanations of the difference between Hodren's and Lubchenco's predictions for the potential increase in sea levels were not answered by press time.
But Rep. John Shadegg (R-Ariz.), a Republican member of the committee, told CNSNews.com that the discrepancy “raises the issue of the credibility of proponents of the argument that the globe is both warming and the cause of that warming is man-made from greenhouse gases.”
Shadegg said the estimates--“if they are to be believed”--differ “by almost 100 percent.”
“These are the two most prominent--at least from the standpoint of government position--scientists in the nation on this issue, and they can’t agree,” Shadegg said.
“And yet, we’re being told the science is settled, and Mr. Gore is saying there’s no longer a debate. That’s funny, it looks to me like--there may not be a debate, but there certainly is not a consensus and there certainly are discrepancies by the two top scientists within the government supposedly on the entire topic.”
“I don’t think that somebody who is involved in a public policy position can rely on data that is that inherently inconsistent,” he added.
“I’m sure they’ll have an explanation--they always have an explanation,” Shadegg said. “But it seems to me that before . . . policy makers, or quite frankly the White House and its EPA, force on the American people dramatic and even draconian changes in public policy that could – and will --significantly affect the lives of the American people, I would suggest they need to get their act together.”
Calculations to predict a rise in sea level are subject to a great deal of uncertainty, Jonathan H. Sharp, professor of oceanography at the University of Delaware, told CNSNews.com. "Sea level rise is not just a function of the sea, but a function of the land," said Sharp. "It's a very complex calculation and there are many other things related to climate change that are much firmer."