Climate

NOAA Study Confirms Global Warming Speed-Up Is Imminent

CREDIT:

A major new study from NOAA finds more evidence that we may be witnessing the start of the long-awaited jump in global temperatures. As I reported in April, many recent studies have found that we are about to enter an era of even more rapid global warming.

Indeed, one March study, “Near-term acceleration in the rate of temperature change,” warns the speed-up is imminent — with Arctic warming rising a stunning 1°F per decade by the 2020s.

The new study in Science from a team of NOAA scientists, “finds that the rate of global warming during the last 15 years has been as fast as or faster than that seen during the latter half of the 20th Century,” as NOAA explains.

The director of NOAA’s National Centers for Environmental Information, Thomas Karl, told the UK Guardian that “considering all the short-term factors identified by the scientific community that acted to slow the rate of global warming over the past two decades (volcanoes, ocean heat uptake, solar decreases, predominance of La Niñas, etc.) it is likely the temperature increase would have accelerated in comparison to the late 20th Century increases.”

What happens when these various temporary factors stop? Karl explained: “Once these factors play out, and they may have already, global temperatures could rise more rapidly than what we have seen so far.”

In other words, the long-awaited jump is global temperatures is likely imminent. How big is the jump? As I reported in April, top climatologist Kevin Trenberth has said it would be as much as 0.5°F. Given that 2015 is crushing it for the hottest year on record, we appear to be already witnessing a big piece of that jump.

NOAA’s new study not only incorporates the latest global temperature data from 2013 and 2014. Their “calculations also use improved versions of both sea surface temperature and land surface air temperature datasets” (detailed here). The result, as NOAA explains, is that the new “study refutes the notion that there has been a slowdown or ‘hiatus’ in the rate of global warming in recent years.” In particular, the authors conclude bluntly:

Indeed, based on our new analysis, the IPCC’s statement of two years ago – that the global surface temperature “has shown a much smaller increasing linear trend over the past 15 years than over the past 30 to 60 years” – is no longer valid.

Turns out the “long-term global warming trend” — which is redundant because the global warming trend was always a long-term phenomenon — has remained constant. But then CP readers already knew that. Back in January I reported that Dr. Gavin Schmidt, director of NASA’s Goddard Institute of Space Studies, tweeted, “Is there evidence that there is a significant change of trend from 1998? (Spoiler: No.)” He posted this chart:

NASA temperature data.

NASA temperature data dispel the myth of a recent slow-down in long-term warming trend. But there was a big jump in temps during the mid-1990s. Many scientists believe we may be witnessing the start of another jump.

On Thursday, Schmidt posted on RealClimate an excellent analysis of the faux pause.

The March study mentioned earlier makes clear the only “pause” there has been was in the long-expected speed-up of global warming. The rate of surface warming should have started to accelerate in the past decade, rather than stay fairly constant.

The authors warned that, by 2020, human-caused warming will move the Earth’s climate system into a regime of rapid multi-decadal rates of warming. They project that within the next few years, “there is an increased likelihood of accelerated global warming associated with release of heat from the sub-surface ocean and a reversal of the phase of decadal variability in the Pacific Ocean.”

That appears to be happening now.