NASA reported today some truly shocking findings on the melting of the Greenland ice sheet this summer:

Satellites See Unprecedented Greenland Ice Sheet Surface Melt

July 24, 2012: For several days this month, Greenland’s surface ice cover melted over a larger area than at any time in more than 30 years of satellite observations. Nearly the entire ice cover of Greenland, from its thin, low-lying coastal edges to its two-mile-thick center, experienced some degree of melting at its surface, according to measurements from three independent satellites analyzed by NASA and university scientists.

On average in the summer, about half of the surface of Greenland’s ice sheet naturally melts. At high elevations, most of that melt water quickly refreezes in place. Near the coast, some of the melt water is retained by the ice sheet and the rest is lost to the ocean. But this year the extent of ice melting at or near the surface jumped dramatically. According to satellite data, an estimated 97 percent of the ice sheet surface thawed at some point in mid-July.

Extent of surface melt over Greenland’s ice sheet on July 8 (left) and July 12 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12.

We reported last month on the “Unprecedented May Heat In Greenland,” where the temperature hit 76.6°F. So it would seem that unprecedented heat leads to unprecedented melting.

I saw the ABC News story tonight, which had the headline quote. I’ll post the video when it is online.

The NASA release has more detail:

Son Nghiem of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., was analyzing radar data from the Indian Space Research Organisation’s (ISRO) Oceansat-2 satellite last week when he noticed that most of Greenland appeared to have undergone surface melting on July 12. Nghiem said, “This was so extraordinary that at first I questioned the result: was this real or was it due to a data error?”

Nghiem consulted with Dorothy Hall at NASA’s Goddard Space Flight Center in Greenbelt, Md. Hall studies the surface temperature of Greenland using the Moderate-resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites. She confirmed that MODIS showed unusually high temperatures and that melt was extensive over the ice sheet surface.

Thomas Mote, a climatologist at the University of Georgia, Athens, Ga; and Marco Tedesco of City University of New York also confirmed the melt seen by Oceansat-2 and MODIS with passive-microwave satellite data from the Special Sensor Microwave Imager/Sounder on a U.S. Air Force meteorological satellite.

The melting spread quickly. Melt maps derived from the three satellites showed that on July 8, about 40 percent of the ice sheet’s surface had melted. By July 12, 97 percent had melted.

This extreme melt event coincided with an unusually strong ridge of warm air, or a heat dome, over Greenland. The ridge was one of a series that has dominated Greenland’s weather since the end of May. “Each successive ridge has been stronger than the previous one,” said Mote. This latest heat dome started to move over Greenland on July 8, and then parked itself over the ice sheet about three days later. By July 16, it had begun to dissipate.

Even the area around Summit Station in central Greenland, which at 2 miles above sea level is near the highest point of the ice sheet, showed signs of melting. Such pronounced melting at Summit and across the ice sheet has not occurred since 1889, according to ice cores. . . .

“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. “But if we continue to observe melting events like this in upcoming years, it will be worrisome.”

That statement is a classic example of what James Hansen called “scientific reticence.”

The scientific literature and recent observations — along with our ongoing lack of climate action — have long passed the worrisome stage (see the post last month “Greenland Ice Sheet Melt Nearing Critical ‘Tipping Point’ ” and links below).

Neven’s Arctic Sea Ice blog notes that “In the meantime Dr. Jason Box reports on the Meltfactor blog“:

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Nobel prize-winning economist Paul Krugman had a great column in the New York Times Monday, “Loading The Climate Dice.”

He discusses the forthcoming paper on “The New Climate Dice,” by NASA’s James Hansen along with Makiko Sato and Reto Ruedy, in which they attribute some of the uber-extreme heat waves to global warming. I blogged on the first draft of that paper back in January (click here, excerpted below).

Krugman ends his discussion this way:

This drought has already sent corn prices to their highest level ever. If it continues, it could cause a global food crisis, because the U.S. heartland is still the world’s breadbasket. And yes, the drought is linked to climate change: such events have happened before, but they’re much more likely now than they used to be.

Now, maybe this drought will break in time to avoid the worst. But there will be more events like this. Joseph Romm, the influential climate blogger, has coined the term “Dust-Bowlification” for the prospect of extended periods of extreme drought in formerly productive agricultural areas. He has been arguing for some time that this phenomenon, with its disastrous effects on food security, is likely to be the leading edge of damage from climate change, taking place over the next few decades; the drowning of Florida by rising sea levels and all that will come later.

And here it comes.

Will the current drought finally lead to serious climate action? History isn’t encouraging. The deniers will surely keep on denying, especially because conceding at this point that the science they’ve trashed was right all along would be to admit their own culpability for the looming disaster. And the public is all too likely to lose interest again the next time the die comes up white or blue.

But let’s hope that this time is different. For large-scale damage from climate change is no longer a disaster waiting to happen. It’s happening now.

For updates of my discussion of “Dust-Bowlification,” see “We’re Already Topping Dust Bowl Temperatures — Imagine What’ll Happen If We Fail To Stop 10°F Warming.” For a discussion of the impacts of Dust-Bowlification on food, see “Climate Story of the Year: Warming-Driven Drought and Extreme Weather Emerge as Key Threat to Global Food Security.”

Here is some chart-filled analysis of Hansen’s paper from my January post:

“Climate dice,” describing the chance of unusually warm or cool seasons relative to climatology, have become progressively “loaded” in the past 30 years, coincident with rapid global warming.  The distribution of seasonal mean temperature anomalies has shifted toward higher temperatures and the range of anomalies has increased.  An important change is the emergence of a category of summertime extremely hot outliers, more than three standard deviations (σ) warmer than climatology.

This hot extreme, which covered much less than 1% of Earth’s surface in the period of climatology [1951-1980], now typically covers about 10% of the land area.  We conclude that extreme heat waves, such as that in Texas and Oklahoma in 2011 and Moscow in 2010, were “caused” by global warming, because their likelihood was negligible prior to the recent rapid global warming.  We discuss practical implications of this substantial, growing climate change.

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