The latest was in a front-page San Francisco Chronicle article Report: rising seas could cost Ca. more than $100B, by Jason Dearen, Associated Press Writer, Wednesday, March 11, 2009.
The prediction of a 1.4-meter sea-level rise over the next century is based on international climate change models that predict more land ice melting as warming continues.
On Tuesday, top climate scientists in Copenhagen, Denmark said new research suggests that current international predictions of sea level rise are too conservative, and warned that seas could rise twice as much as previously projected.
Al Gore, of course, predicted that sea levels would rise 20 feet by 2100, over four times the amount of this most extreme current projection and about ten times what the Intergovernmental Panel on Climate Change (IPCC) has led us to expect.
The prediction that sea levels would rise 1.4 meters (4.6 feet) by 2100 really got my attention. The first thing that hit me was that we are already nine percent of the way this century to 2100, so we should have already experienced five inches of rising sea levels – over half of the total for the past century - if we’re going to get to 4.6 feet by 2100. So far sea levels have risen 0.7 inches since 2000, leaving us needing an increase of over 4.5 feet in the next 91 years (or an increase of 19.9 feet to satisfy Al Gore).
Have there been sea level increases in the past as great as 4.6 feet in a century? There certainly have; since the end of the last Ice Age 18,000 years ago sea levels have risen over 400 feet, an average of over two feet per century. Of course the rate was about double the two-foot average during the first 10,000 years following the end of the Ice Age because there was so much ice to melt and warming was much faster than currently.
By the Holocene Climate Optimum, a warmer period than today which lasted from 9,000 to 5,000 years ago, sea level increases of approximately 400 feet had occurred, and in the last roughly 8,000 years sea levels have only risen a total of about 40 feet, or an average of half a foot per century.
Remarkably, given the dire prophecies of sea levels rising 4.6 feet this century, the Holocene Climate Optimum had exceptional warming in northern latitudes and yet sea level increases per century apparently did not exceed one foot. Why would warming of a lesser magnitude now cause melting of a far greater magnitude? It didn’t during the Medieval Warm Period (800 to 1300 AD), when tree lines in the Alps were 300 meters higher than today and Greenland glaciers had retreated much farther than at present.
This last point is significant, because according to Al Gore and his global warming alarmists, Greenland is particularly vulnerable to suddenly melting. Interestingly, scientists who have carefully studied Greenland don’t see how Gore’s or others’ dire prophesies can be fulfilled. There is ample evidence that the Greenland ice cap has withstood longer periods of warmth without significant shrinkage, and there are enormous physical barriers to sudden ice movement and rapid changes that would cause flooding. Very accurate records also show that Greenland was much warmer sixty to eighty years ago than it is now.
Temperatures were warmer in the 1930s and 1940s in Greenland. They cooled back to the levels of the 1880s by the 1980s and 1990s. In a GRL paper in 2003, Hanna and Cappelen showed a significant cooling trend for eight stations in coastal southern Greenland from 1958 to 2001 (-1.29ºC for the 44 years). The temperature trend represented a strong negative correlation with increasing CO2 levels.
We must thank Al Gore for drawing our attention to Greenland, where temperatures went down as CO2 increased for half a century. Besides the strong negative correlation between temperatures and CO2 in Greenland, scientists have found a strong positive correlation between temperatures and the Atlantic Multidecadal Oscillation.
That’s right, Al. Scientists have found a strong positive correlation with a natural force, not an anthropogenic one.
Warming in the Arctic is likewise shown to be cyclical in nature. This was acknowledged in the AR4 (the Fourth Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC)) which mentioned the prior warming and ice reduction in the 1930s and 1940s. Warming results in part from the reduction of arctic ice extent because of flows of the warm water associated with the warm phases of the PDO (Pacific Decadal Oscillation) and AMO (Atlantic Multidecadal Oscillation) into the arctic from the Pacific through the Bering Straits and the far North Atlantic and the Norwegian Current.
Polyakov et al (2002) created a temperature record using stations north of 62 degrees N. The late 1930s-early 1940s were clearly the warmest of the last century. In addition, the numbers of available observations in the late 1930s-early 1940s (slightly more than 50) is comparable to recent decades.
The same is true for the Antarctic Ice Cap, which arguably has been increasing and would increase if warmer temperatures cause increased precipitation.
Warmer temperatures are, of course, at the heart of this issue, and I suggest that no one will be able to argue anthropogenic global warming convincingly when confronted by Climate Change: Driven by the Ocean not Human Activity, by William M. Gray, Professor Emeritus, Dept of Atmospheric Science, Colorado State University (Prepared for the 2nd Annual Heartland Institute sponsored conference on Climate Change, New York City, March 8-10, 2009). In his presentation Dr. Gray clearly demonstrates that doubling of atmospheric CO2 will only increase global temperatures about one degree Fahrenheit this century. In other words, there will be no warming engine to drive Antarctic and Greenland melting and concomitant significant rising of sea levels.
Sorry Al. By 2100 you’re going to be stuck with over 19 feet in your mouth, and the more cautious scientists predicting a 4.6-foot rise will come up four feet short.
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