NASA shocker: Last month was hottest July, and hottest month, on record

It's the first time we've seen such a record month in the absence of an El Niño boost.

July 2017 hottest
The GISTEMP monthly temperature anomalies superimposed on a 1980-2015 mean seasonal cycle. CREDIT: NASA

July 2017 has narrowly topped July 2016 as the hottest July on record, according to a shocking analysis by scientists at NASA’s Goddard Institute for Space Studies (GISS) released Tuesday. As a result, July 2017 is statistically tied with August 2016 (and July 2016) as the hottest month on record.

What’s so surprising here is that records for warmest month or year almost invariably occur when the underlying human-caused global warming trend gets a temporary boost from an El Niño’s enhanced warming in the tropical Pacific.

But whereas 2016 set its temperature records boosted by one of the strongest El Niño’s on record, 2017 is setting records in the absence of any El Niño at all.

“Yes, it’s surprising that July 2017 tied for warmest month on record despite not having the El Nino assist of July and August 2016,” prominent climatologist Michael Mann wrote in an email to ThinkProgress. “The extreme warmth of the Antarctic peninsula is particularly worrying given the disintegration of the Larsen C ice shelf we’ve been hearing so much about.”


NASA charts exactly where it was hot in July compared to the 1951-1980 average (see map below). Note that to show the extreme warming around Antarctica, the high end of the temperature legend had to be extended to a whopping 8°C (14.4°F).

NASA’s land and ocean temperature index (LOTI) vs the 1951-1980 average.
NASA’s land and ocean temperature index (LOTI) vs the 1951-1980 average.

When we see all-time global temperature records in the absence of any El Niño, that sends a message the underlying global warming trend is stronger than ever — and that we are running out of time to stop catastrophic impacts.

NOTE: NOAA releases its own monthly temperature report in a few days using slightly different data so it is possible they will have a different ranking for July 2017.