New research has further eroded a go-to argument from climate change deniers: that there’s been a significant slowdown, or hiatus, in global warming.
In June 2015, scientists from the National Oceanic and Atmospheric Administration challenged this belief by publishing a controversial study that updated the global temperature record and significantly increased the estimated rate of global warming over the previous 15 years.
Skeptics quickly pounced on the federal agency, accusing scientists of fudging data and orchestrating a “cover-up.” Rep. Lamar Smith (R-Texas), who chairs the House Committee on Science, Space, and Technology and has a long history of denying mainstream climate science, subpoenaed NOAA scientists to obtain communications related to their analysis.
Now, after a year of reviewing independent climate data, researchers at the University of California, Berkeley, say they have confirmed the accuracy of NOAA’s findings. In other words, the agency did not, as Smith claimed, manipulate data “to get the results they needed to advance [the Obama] administration’s extreme climate change agenda.”
“They weren’t cooking the books,” Zeke Hausfather, the study’s lead author and a graduate student in UC Berkeley’s Energy and Resources Group, told The Huffington Post.
The 2015 paper, led by NOAA scientist Thomas Karl and published in the journal Science, found that an apparent slowing trend in sea surface temperatures from 1998 to 2012 was the result of biased data. In its update, the agency corrected its analysis to account for differences between ships’ measurements and those of more accurate at-sea buoys.
As InsideClimate New reported at the time, NOAA found that the planet had warmed 0.086 degrees Celsius per decade between 1998 and 2012 ― more than double the previous estimates by the United Nations’ Intergovernmental Panel on Climate Change. When factoring in 2013 and 2014, the per-decade temperature increase jumped to 0.116 degrees Celsius.
“Our new analysis,” Karl said at the time, “suggests that the apparent hiatus may have been largely the result of limitations in past datasets, and that the rate of warming over the first 15 years of this century has, in fact, been as fast or faster than that seen over the last half of the 20th century.”
“The new NOAA temperature record is probably the best estimate of global ocean temperatures over the last 15 years.”
- Zeke Hausfather, UC Berkeley’s Energy and Resources Group
For their own study, published Wednesday in the online journal Science Advances, Hausfather and his team combed through independent data collected from satellites, floating buoys and Argo floats ― autonomous devices that sink in the ocean and record temperature and salinity on their way back to the surface. Hausfather said the data from all three instruments “agree almost perfectly” with NOAA’s latest analysis, confirming there was no hiatus and reinforcing the agency’s finding that warming in recent years had been underestimated.
“These results serve as a robust, independent validation of the NOAA temperature record, and show us that the new NOAA temperature record is probably the best estimate of global ocean temperatures over the last 15 years,” Hausfather said in a video accompanying the new study.
Michael Mann, a climate scientist at Pennsylvania State University, is among those who have acknowledged the existence of a warming slowdown ― and urged colleagues not to sweep it under the rug.
Asked about the new study, Mann told The Huffington Post it further validates what he and others in the field have been saying: that the slowdown was “temporary and is clearly over.”
“2016 will be the 3rd consecutive record breaking year for global temperatures,” he wrote in an email. “We’ve never seen 3 consecutive record breakers before.”
The research team, which also included Kevin Cowtan of the University of York’s department of chemistry and Mark Richardson of NASA‘s Jet Propulsion Laboratory, began working on the study a little over a year ago. Along with setting the record straight, Hausfather hopes the results will relieve some of the pressure the scientific community faces, particularly in light of the incoming presidential administration, he told HuffPost.
“People don’t get much credit for doing studies that replicate or independently validate other people’s work,” he said in a release. “But, particularly when things become so political, we feel it is really important to show that, if you look at all these other records, it seems these researchers did a good job with their corrections.”
Cowtan added that the “political controversy manufactured around the NOAA paper provided a strong motivation” for conducting the study.
There’s growing concern in the scientific community about what a Donald Trump presidency might mean for the fight against global warming. Trump has dismissed climate change as “bullshit” and a Chinese “hoax” and has promised to pull the U.S. out of the historic Paris climate agreement. He has also said he would cut all federal spending on the issue.
Smith did not immediately respond to a request for comment for this story.
This story has been updated to include comments from Mann and Cowtan.
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