It’s increasingly likely that 2015 will be the hottest year on record, possibly by a wide margin.
NASA reported Wednesday that this was the hottest four-month start (January to April) of any year on record. This was also the second-warmest April on record in NASA’s dataset.
The National Oceanic and Atmospheric Administration (NOAA) has just predicted a 90 percent chance that the El Niño it declared in March will last through the summer and “a greater than 80 percent chance it will last through 2015.” El Niños generally lead to global temperature records, as the short-term El Niño warming adds to the underlying long-term global warming trend.
And in fact, with April, we have once again broken the record for the hottest 12 months on record: May 2014 – April 2015. The previous record was April 2014 – March 2015, set last month. The record before that was March 2014 – February 2015. And the equally short-lived record before that was February 2014 – January 2015.
As we keep breaking records in 2015, our headlines are going to sound like a … broken record. May has already started out hot, and it is quite likely next month we will report “The Hottest 5-Month Start Of Any Year On Record,” and that June 2014 – May 2015 will become hottest 12 months on record.
This chart uses a 12-month moving average, so we can “see the march of temperature change over time,” rather than just once every calendar year, as science writer Greg Laden puts it.
The global warming trend that made 2014 the hottest calendar year on record is continuing. Some climate scientists have said it’s likely we’re witnessing the start of the long-awaited jump in global temperatures — a jump that could be as much as as 0.5°F.
April was warm across the country and most of the world. That’s clear in the NASA global map below for April temperatures, whose upper range extends to 6.9°C (12.4°F) above the 1951-1980 average.
Once again, it was quite warm last month in Siberia, where the permafrost is fast becoming the perma-melt. The permafrost contains twice as much carbon as is currently in the entire atmosphere. The faster it turns into a significant source of carbon dioxide and methane emissions, the more humanity will be penalized for delaying climate action. The defrosting may add as much as 1.5°F to total global warming by 2100 — something that is not factored into any current climate models.
h/t Greg Laden