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Absolutely, Positively Not a Sign of Global Warming

This isn’t a post about how hot the U.S. is getting. This is a post about how hot Greenland is getting—and why, maybe, we should care about it.

On July 16, a NASA satellite photographed a iceberg breaking off from the Petermann Glacier, a massive sheet of ice that is on the northwest side of Greenland, contiguous to the Arctic Ocean and parts of Canada. The iceberg, which is not expected to threaten shipping, is about 46 square miles or roughly twice the size of Manhattan. 

The “calving” of icebergs from glaciers is a natural process and, just two years ago, an even larger piece of ice broke off from Petermann. No credible scientist would suggest this one event, in isolation, is evidence of global warming. As BBC Science and Technology reporter Jason Palmer writes, 

The truth is that the questions are devilishly difficult to answer—the stability of ice sheets at both the Earth’s poles depends on a wide range of factors, from atmospheric temperatures to the temperatures of the surface of the sea, to the degree of sea ice cover.

But as part of a broader pattern, this latest event is certainly consistent with a story of global warming. From Discover’s "Bad Astronomy" blog:

As before, we can speculate whether this is due to global warming or not. Icebergs calf all the time. However, note that the last time, the berg calved later in the summer (August), and this crack is much farther up the glacier than usually seen.
As climate scientist Michael Mann says, global warming is like loaded dice. You don’t know if any particular throw of snake eyes is due to them being fixed, but you’ll see a lot more rolls turn up snake eyes than you would otherwise. Global warming is predicted to give us longer, hotter summers, drier conditions across the US, more record temperatures, thinner arctic ice, and having it cover less surface area of the Earth. And, yes, more frequent glacier calving.
By the way, the 2010 calving event was the largest seen in nearly 50 years. And also by the way, June 2012 was one of the hottest since records have been kept. And also also by the way June 2012 had the highest land and ocean average surface temperatures in the northern hemisphere in recorded history. And oh, one more thing: it also was the 328th consecutive month with a global temperature higher than the 20th century average. You can read all about this in the NOAA report "State of the Climate Global Analysis" for June 2012.

ThinkProgress has more information, with more photos, on why, generally speaking, scientists think melting ice in Greenland is evidence of global warming.

NASA Earth Observatory image by Jesse Allen, using data from the Land Atmosphere Near real-time Capability for EOS (LANCE)

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