Wednesday, March 11, 2015

Climate Change: That Is All

In the movie M*A*S*H, someone would periodically announce upsetting news like “The US announced today that it had tested a nuclear device with one thousand times the explosive power of the bomb at Hiroshima” in a matter-of-fact voice, and would end the announcement with a brief “That is all.”

A recent study has now projected that under the “best-case scenario” (now changed to have atmospheric carbon level off at 525 ppm rather than just above 400 ppm) temperatures over the middle of the 21st century will increase by 0.5 degree F per decade, and in the Arctic by 1 degree F.  In the worst-case scenario, temperatures will increase by 1 degree F per decade, and in the Arctic by 2 degrees F.  None of these scenarios take into account melting permafrost, which is likely to increase atmospheric carbon and the increase in temperature yet further.

In the Arctic, after 2 years in which sea ice minima reverted to a little above the level of 2007, it now appears very likely that the yearly maximum will be well below past recorded maxima, and will be the first recorded maximum at less than 14 million km.  Meanwhile, a weak el Nino has been announced, and in the past el Ninos have been associated with accelerated sea ice melting over the summer.  Another recent study has shown that on average 65 % of Arctic sea ice has vanished since 1975, and 85 % at sea ice minimum in September.  Another study has found that a so-called “hiatus” or “slowdown” over the last 15-20 years in global warming does not exist once Arctic data are added.  It is anticipated that over the next few decades, the global warming will speed up instead of rising at a constant rate, and therefore warming south of the Arctic will likewise speed up.

Another study has shown that melting of Greenland land ice is proceeding faster than previously thought, and therefore its contribution to sea level rise in the next few decades is going to be greater than anticipated (in previous studies that projected a 6 foot rise by the end of the century).  In the Antarctic, likewise, studies show the present rate of land ice melt has been underestimated, and therefore that Antarctic melting will likewise contribute significantly to sea level rise.

Finally, atmospheric carbon measurements for February are now out.  For the first time since records began to be kept in the 1950s, February atmospheric carbon is above 400 ppm, and approximately 2.5 ppm above last year.

That is all.

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