“Sea levels may rise by 9 inches this century, scientists warn” reads the headline from the UK newspaper The Independent, reporting on a new Science magazine study (subs. req’d). You would probably surmise from this headline that the study predicted sea levels may rise by a mere 9 inches this century. But it didn’t.
The study predicted sea levels may rise by 9 inches the century just from the melting of inland glaciers and ice caps–not from either thermal expansion of the water or from dynamic destruction of either the Greenland or Antarctic ice sheets.
Actually, the story itself gets it mostly right — “This does not include the rise in sea levels caused by the thermal expansion of water, which could potentially double this figure.”
But the headline writer has insured that the vast majority of people who don’t read the story will think sea level rise this century is no big deal.
Interestingly, the authors of this study are quite confident the loss of inland ice will raise sea levels more this century than loss of ice from the great eye sheets — a very many, like Nasa’s James Hansen (who fears 17 feet of sea level rise or more by 2100), do not share.
So why did the recent U.N. report low-ball sea level rise this century?
Asked why the last report of the IPCC estimates a lower increase in sea-level rise, Professor Meier said that the scientists had to deal with scientific data that was out of date by the time the latest report of the IPCC was published this year. “They were restricted to the use of numbers in the peer-reviewed literature that was published before early 2006. And some of that data was gathered long before that. We used data that was newer,” he said.
The U.N. report also missed the 2007 analysis by Rahmstorf, which concluded:
A rise of over 1 m by 2100 for strong warming scenarios cannot be ruled out, because all that such a rise would require is that the linear relation of the rate of sea-level rise and temperature, which was found to be valid in the 20th century, remains valid in the 21st century.