One thousand six hundred and eighteen (1618) — that’s how many months we have in all of the global temperature record starting in 1880. And early indications are that October of 2015 was possibly the hottest month out of them all. A record hot month, during a record hot year, in a record hot world. A new extreme temperature record that may just stand for one or two months as temperatures are likely to continue to climb coordinate with the peak of a Monster El Nino in the Pacific.

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As of today’s NOAA El Nino report, sea surface temperatures in the key Nino 3.4 zone had hit a range of 2.7 degrees Celsius above the climatological average. These temperatures are about equal to maximum weekly values achieved during the 1997 El Nino — which in many respects was considered to be the strongest on record. This most recent heat spike puts the 2015 El Nino within striking distance of being the most intense El Nino ever witnessed.

(A sky-rocketing global ocean heat content is, through the agency of a monster El Nino, in the process of backing up into the atmosphere — pushing global temperatures to new all-time record highs. Image source: NOAA NODC.)

As with most El Ninos, the result is that excess ocean heat is backing up into the atmosphere at a heightened rate — pushing global temperatures higher. In a normal year, on a normal Holocene Earth, this would have temporarily spiked atmospheric temperatures. But this year, the record El Nino is being fueled by oceans that are taking in an unprecedented amount of heat. Heat re-radiated by an atmosphere loaded with greenhouse gasses in the range of 400 ppm CO2 and 485 ppm CO2e. And now the oceans, being the greatest store of heat energy on Earth and sucking up more than 90 percent of the added heat due to human forced warming, are returning the favor.

Hottest October on Record

As a result, the world is now experiencing some of the hottest temperatures ever seen. The year of 2014, when the Pacific began to settle into the current El Nino trend, was the hottest on record. But that new global high temperature mark didn’t last long. For as that human-accumulated ocean heat continued to bleed back into the atmosphere, 2015 set a path to supplant 2014 as the new record holder. Global temperatures were raging to new heights. But the worst was still to come.

With a record El Nino starting to hit its peak in a hothouse world what we’re in for over the next few months is likely to be something, yet again, unprecedented. And already, early NCAR data reanalysis points toward October of 2015 being the hottest month ever recorded.

(Reanalysis of NCAR global temperature data shows that October of 2015 was the hottest month in the global climate record. Temperature averages in the above graph are comparable to a 1994 to 2013 baseline that’s about 0.7 degrees Celsius hotter than 1880s averages. The new departure, according to Nick Stoke’s reanalysis is +0.2 C hotter than September and +0.15 C hotter than the previous hottest month ever recorded — January of 2007. Image source: Moyhu.)

According to early reports from Nick Stokes (a retired CSIRO scientist) at the climate blog Moyhu, NCAR temperature reanalysis has put October at the hottest in the global climate record at +0.567 C above the 1994 to 2013 average. This shoves October into the range of +1.18 C above the 1951 to 1980 average and about +1.38 C above 1880s averages (in the NCAR context). Since GISS has tended to range a bit cooler than the NCAR figures this Fall, Nick estimates LOTI temperatures from the NASA analysis are likely to hit a range of +1 C above the NASA baseline or about +1.2 to +1.3 C above 1880s values in that measure.

If these NCAR comparisons bear out, they would make October of 2015 the hottest month in all of the global climate record in both the NCAR and the GISS measures. Notably, Nick Stokes NCAR figure shows a substantial +0.15 C departure above the previous record during January of 2007. A NASA GISS figure of +1 C would also beat out January of 2007 as the hottest month ever in the global climate record, but by a somewhat smaller +0.03 C margin.

Even so, as a record or near record El Nino continues to hit maximum warmth in the Pacific, it is likely that more monthly global temperature records are in the pipe. Peak surface global temperatures typically occur during the months after El Nino hits top intensity. So it is both possible and likely that November, December, January, February and even March could continue to explore new maximum monthly temperature thresholds. Meanwhile, the inertia of all that extra ocean heat bleeding back into the atmosphere presents a decent chance that 2016 could even beat out 2015 as the new yearly record holder. It all really depends on if El Nino spikes still higher and if that peak extends significantly into next year.

In any case, the human hothouse is again re-writing the record books.

Links:

NOAA’s Weekly El Nino Report

NOAA NODC

NCAR/NECP Index up 0.2 C in October

NASA GISS

Hat Tip to Wharf Rat