Record-smashing August means long-awaited ‘jump’ in global warming is here

Every month of 2016 has set a temperature record.

NASA temperature analysis for August: “Another month, another record.” Credit: NASA
NASA temperature analysis for August: “Another month, another record.” Credit: NASA

We appear to be in the midst of the long-awaited jump in global temperatures.

And that means “The kinds of extreme weather we have seen over the past year or so will be routine all too soon, but then even worse records will be set,” as Kevin Trenberth, one of the world’s leading climatologists, told me.

NASA has reported that last month was not merely “the warmest August in 136 years of modern record-keeping,” it tied with this July 2016 for the “warmest month ever recorded.” And for 11 straight months (starting October 2015), the world has set a new monthly record for high temperature.

So even though 2014 set the record at the time for the hottest year — and then 2015 crushed that record, NASA says there is a greater than 99 percent chance 2016 will top 2015. And it probably won’t be close according to this projection tweeted out by NASA’s Gavin Schmidt:

Land and ocean temperature index (LITI) with 2016 prediction. Credit: NASA
Land and ocean temperature index (LITI) with 2016 prediction. Credit: NASA

Why does this string of record-setting months and years matter? As I reported last year, climatologists have been expecting a “jump” in global temperatures. There is “a vast and growing body of research,” as Climate Central explained in February 2015 that “humanity is about to experience a historically unprecedented spike in temperatures.”

A March 2015 study, “Near-term acceleration in the rate of temperature change,” makes clear that an actual acceleration in the rate of global warming is imminent — with Arctic warming rising a stunning 1°F per decade by the 2020s.

More than 90 percent of global heating goes into the oceans (see excellent article here) — and ocean warming has accelerated in recent years. Climatologist Kevin Trenberth of the National Center for Atmospheric Research explained here in 2013 that “a global temperature increase occurs in the latter stages of an El Niño event, as heat comes out of the ocean and warms the atmosphere.”

Well, we are indeed at the end of an El Niño event, and we have indeed seen a big global temperature increase. In April 2015, Trenberth told me thought “a jump is imminent.” Previously he had explained that this jump could be 0.2°C or 0.3°C, which is to say up to 0.5°F! That change would happen “relatively abruptly,” but last for 5 or 10 years before it jumped again.

It looks like Trenberth was right (though it will take a few years to know for sure). When I asked him to comment on the stunning jump in global temperatures we’ve seen in the last 18 months, he said:

“The increase in carbon dioxide and other heat trapping gases from human activities is relentless. The effects on global mean surface temperatures can be masked by natural variability for a decade or a bit more, but as the natural variability goes in the other direction, suddenly it is quite a different story and record after record gets broken.”

That’s where we are. Global temperatures often jump over a couple years, then they rise more slowly, like a staircase (or ladder) where the steps are sloped up. The climate science deniers make a lot of noise during the short periods of slower warming, and stay strangely quiet during the jumps. Go figure!

Trenberth explains that “the nature of the changes going on now suggest that we have made another step up the ladder to another rung, and we won’t go down again.” That means the recent bouts of extreme weather “will be routine all too soon, but then even worse records will be set. It is not something to welcome and it is hard to plan for.”

It is time to slash carbon pollution so we can stop climbing this stairway of ever-worsening extreme weather and climate change.