Greenland ice melt

Post image for The Greenland Ice Melt: Should We Be Alarmed?

If you follow global warming news at all, you’ve probably seen the NASA satellite images (above) many times. The images show the extent of Greenland surface ice melt on July 8 (left) and July 12 (right). In just a few days, the area of the ice sheet with surface melting increased from about 40% to 97%, including Summit Station, Greenland’s highest and coldest spot.

NASA took a drubbing from Patrick Michaels and Chip Knappenberger at World Climate Report (“Illiteracy at NASA“) for describing the ice melt as “unprecedented” in the title of the agency’s press release. The word literally means without precedent, and properly refers to events that are unique and never happened before. In reality, as one of NASA’s experts points out in the press release, over the past 10,000 years, such events have occurred about once every 150 years:

“Ice cores from Summit show that melting events of this type occur about once every 150 years on average. With the last one happening in 1889, this event is right on time,” says Lora Koenig, a Goddard glaciologist and a member of the research team analyzing the satellite data.

Equating ‘rare yet periodic’ with ‘unprecedented’ is incorrect and misleading. “But apparently,” comment Michaels and Knappenberger, “when it comes to hyping anthropogenic global warming (or at least the inference thereto), redefining English words in order to garner more attention is a perfectly acceptable practice.” New York Times blogger Andrew Revkin also chided NASA for an “inaccurate headline” and the associated “hyperventilating coverage,” but for a different reason: NASA provided “fodder for those whose passion or job is largely aimed at spreading doubt about science pointing to consequential greenhouse-driven warming.”

Enough on the spin. Let’s examine the real issues: (1) Did anthropogenic global warming cause the extraordinary increase in surface melting between July 8 and July 12? (2) How worried should we be about Greenland’s potential impact on sea-level rise? [click to continue…]