Hottest 12 months on record, again

Andrew Freedman at Climate Central and Jeff Masters at Weather Underground are both up today with breakdowns and graphics from the National Oceanic and Atmospheric Administration's (NOAA) monthly State of the Climate summary for June, which has just been released.

The big news is that for the second month in a row, the U.S. has racked up its warmest 12-month period on record (that is, July 2011 through June 2012 topped June 2011 through May 2012, the previous record holder).  June 2012 also marked the close of the warmest January-June period on record.

Two of the most notable graphics:

This shows the degree to which 2012--so far--is departing from the four warmest years in the temperature record.

And this shows how far the two 12-month periods ending in May 2012 and June 2012 exceed other 12-month periods in the historical record.

More eye-popping Greenland data

Over at Weather Underground, meteorologist Dr. Jeff Masters has a new post on Greenland, including some recent temperature records and a look at the melting of the giant island's ice cap during 2011:

"The record books for Greenland's climate were re-written on Tuesday, when the mercury hit 24.8°C (76.6°F) at Narsarsuaq, Greenland, on the southern coast. According to weather records researcher Maximiliano Herrera, this is the hottest temperature on record in Greenland for May, and is just 0.7°C (1.3°F) below the hottest temperature ever measured in Greenland. The previous May record was 22.4°C (72.3°F) at Kangerlussuaq (called Sondre Stormfjord in Danish) on May 31, 1991. ...

"Between 2003 - 2009, Greenland lost an average of 250 gigatons [billion tons] of ice per year. In 2011, the loss was 70% greater than that." (This is accompanied by a seriously scary graph showing ice loss from 2003 to 2011.)

To briefly recap the nature of the problem:

- The Greenland ice cap is one of the world's two major land-based ice accumulations along with Antarctica.  "Land-based" is key because when land-based ice melts, it adds to sea level rise. (The Arctic ice cap floats on the ocean, so while it is melting too, that doesn't change sea level.)

- There is enough ice in Greenland's mile-high ice cap to raise global sea levels by 7 meters (23 feet) if it all melts (although that's expected to take hundreds of years to happen).

- Many millions of people live in low-lying coastal areas around the world that will have to be abandoned if sea level continues to rise.

Dr. Masters cites studies that estimate Greenland's current contribution to sea level rise at just 0.7 mm (.03 inches) per year, and expect that rate to double over the next decade.

So, nothing urgent here, just another trend that is headed in the wrong direction and accelerating.  On the other hand, it's also a process that may not be entirely predictable.  See Science News, April 16, 2012, "Greenland may be slip-sliding away due to surface lake melting."

Lest we forget: 2011's 'mind-boggling' weather

Before 2011 totally gets away from us, here is a comment I've been meaning to post about.  It's from a Public Broadcasting System (PBS) interview on the weather of 2011 with Dr. Jeff Masters, co-founder and Director of Meteorology of Weather Underground, and Kathryn Sullivan, deputy administrator of the National Oceanic and Atmospheric Administration (NOAA).
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JEFF MASTERS, Weather Underground: In one year, we had three of the most remarkable extreme weather events in the history of the U.S.  I mean, we talk about the Dust Bowl summer of 1936. Well, this summer pretty much matched that for temperature, almost the hottest summer in U.S. history. We also talk about the great 1974 tornado outbreak. Well, we had an outbreak that more than doubled the total of tornadoes we had during that iconic outbreak. And, also, we talk about the great 1927 flood on the Mississippi River. Well, the flood heights were even higher than that flood this year.  So, it just boggles my mind that we had three extreme weather events that matched those events in U.S. history. (emphasis added)
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I post it here as something to remember--there were many other weather events in 2011, from Hurricane Irene to the Western wildfires and the Phoenix dust storms, but Dr. Masters's comment is a nice sound bite summarizing some ways in which the year really "pushed the [weather] envelope" on a macro scale.