


NASA’s land and ocean temperature index (LOTI) with 2017 prediction. Via NASA’s Gavin Schmidt.

Last month was the second hottest May on record, NASA reported Thursday. Only May 2016 was warmer.

“With May GISTEMP update,” tweeted Dr. Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies (GISS), “my prediction is 2017 will be ~2nd warmest year in the record” [see figure above].

May continues a streak of warmer than average months that dates back to at least August 1985 in NASA’s data set.

But before our millennial readers start writing us that the term generally refers to people born starting in the early 1980s, consider this: July 1985 is only a cooler-than-average month if you use the base period 1951 to 1980, as NASA does for its data. But humans were warming the planet by burning fossil fuels long before then — the Industrial Revolution began over two centuries ago.


So when you use an 1880 to 1899 baseline to reflect the earlier warming, as Schmidt does in the graph above, you see we have to go back much further to find a colder than average year — or month.

Climate Central looked at the monthly data using the earlier baseline and found that “if you were born after December 1964, you’ve never experienced a month cooler than average on this planet.”

That not only covers all millennials — it covers almost all Generation X-ers as well.

As for the future, the odds of a cooler than average month using either baseline is increasingly small. The levels of heat-trapping CO2 in the air are already far outside the bounds of what humans have ever experienced — and the rate of rise is speeding up.

Even before President Donald Trump was elected, achieving the Paris target of keeping total warming “well below” 3.6°F (2°C) was going to be an enormous challenge. But his efforts to undermine domestic climate action and to abandon the Paris climate deal put us back on track to warming of 5° to 10°F.


So that means — short of a monster volcano darkening the skies around the globe — it may be centuries or longer before anybody experiences a cooler than average month again.