Joe Romm: Last Month Was The Hottest March In The Global Satellite Record, And The Arctic Is Still Sizzling

CREDIT: AP PHOTO/BORIS GRDANO

by Joe Romm, Think Progress, April 4, 2016

Last month was the hottest March on record, according to newly-released satellite data. And it followed the hottest February on record.

The Arctic was literally off-the-charts warm last month, as we’ll see. It’s no surprise, then, that Arctic sea ice set a record for the lowest maximum extent.

First, the University of Alabama at Huntsville (UAH) data shows that in March the lower troposphere (the lowest part of the atmosphere) was a remarkable 1.3 °F (0.73 °C) above the historical (1981-2010) average, a baseline that is already some 0.8 °F (0.45 °C) hotter than pre-industrial levels.

The lower tropospheric temperature (LT) anomaly, via UAH scientist Roy Spencer.

Higher highs and higher lows — the warming trend is quite clear in the satellite data. As the UAH’s Roy Spencer and John Christy — both leading deniers — have reported, the UAH data shows a “global climate trend since Nov. 16, 1978 [of] +0.12 °C [0.22 °F] per decade.”

But wait, how is it that Ted Cruz and other climate science deniers keep claiming there hasn’t been any warming in the satellite record since 1998? The short answer is they’ve been ignoring all of the reliable sources that show warming, but have focused on the one satellite record that even Spencer and Christy knew was in error. Now that this error has been corrected in the peer-reviewed literature, as we reported, there aren’t any more datasets that don’t show warming.

“Record-Shattering February Warmth Bakes Alaska, Arctic 18 °F Above Normal,” was the Climate Progress story last month when NASA released its February temperature data. How warm was the Arctic in March? Off the charts.

Look at what the heat did: It kept Arctic sea ice growth almost flat for over a month during a time when sea ice extent normally soars to its annual maximum. The result, as the National Snow and Ice Data Center (NSIDC) reported last week, was the lowest winter maximum on record.

“I’ve never seen such a warm, crazy winter in the Arctic,” reported NSIDC director Mark Serreze. “The heat was relentless.”

The NSIDC has a metric for how warm (or cold) the Arctic has been called “freezing degree days” (FDDs). Their website explains:

The relationship between thermodynamics and sea ice thickness can be thought of most simply in terms of freezing degree days (FDD), which is essentially a measure of how cold it has been for how long. The cumulative FDD is simply daily degrees below freezing summed over the total number of days the temperature was below freezing.

NSIDC scientist Andrew Slater has an amazing chart on his website of freezing degree days in 2016 compared to other years at 80° N latitude:

In the Arctic, 2016 (bottom red line) has been anomalously warm.

“This year’s trend line is not only way outside of the percentile zones,” Neven Acropolis notes at his must-read Arctic sea ice blog, “it’s falling off the chart.” This unusual warmth is a key reason Arctic sea ice extent just saw its lowest maximum on record.

It bears repeating that recent research finds that rapid Arctic warming, driven in part by sea ice loss, is already worsening extreme weather. Also, the permafrost contains twice as much carbon as the atmosphere, and as it defrosts, it releases that carbon in the form of either CO2 or an even more potent heat-trapping greenhouse gas, methane (CH4). Thus as Arctic warming speeds up, it boosts global greenhouse gas levels, which leads to even more warming of the Arctic and so on.

That’s why we must pay attention to what happens in the Arctic — and do everything we can to stop global warming ASAP.

http://thinkprogress.org/climate/2016/04/04/3765965/hottest-march-satellite-record/