Various studies have debunked the idea of a pause, or hiatus, in global warming—the contention that global surface temperatures stopped rising during the first decade of this century. The arguments for and against “the pause” were somewhat muted until June 2015, when scientists at the National Oceanic and Atmospheric Administration published a paper in Science saying that it had slightly revised the sea surface temperatures it had been citing for the 1900s. The measurement methods, based on sensors in the engine intake ports of ships, had been flawed, NOAA said. The revised methodology also meant that sea surface temperatures during the 2000s had been slightly higher than reported. NOAA adjusted both records, which led to a conclusion that global surface temperatures during the 2000s were indeed higher than they had been in previous decades. No hiatus.
Critics attacked NOAA, claiming it had cooked the books to dismiss claims of a pause. Republican Rep. Lamar Smith of Texas opened a congressional investigation of NOAA scientists, including demands that they turn over their emails, which they have not.
Now independent scientists have weighed in. A study published Wednesday in Science Advances shows that the adjustments NOAA made were justified. A team led by Zeke Hausfather at the University of California at Berkeley and Kevin Cowtan at the University of York analyzed raw data from buoys, satellites and robotic sensors around the world’s oceans. They concluded that the old methods had indeed overestimated sea surface temperatures in the past—but that the newer calculations had underestimated temperatures for the 2000s.
Hausfather and Cowtan explain their review in a guest blog Wednesday on Scientific American’s Website, and make a case for why such investigations should be done by independent scientists, not politicians. Hausfather also describes the details of his team’s analysis in a clear and interesting video, below.
“The bottom line,” Hausfather says, “is that NOAA got it right. They were not manipulating the data for any political purpose. Warming has continued.”