Responding to a senator's question sent to him after his confirmation hearing, Pruitt stated: “Over the past two decades, satellite data indicates there has been a leveling off of warming.” That’s the statement the nine scientists undertake to refute.
Several things about the Santer study would be remarkable but for the politicization of climate science that has become the new normal.
The first is that any scientist would bother to write such a study. Take a look at Figure 1A, ignore the El Niño spikes of 1998 and 2016, which are inappropriate end points for plotting the greenhouse effect, and draw a straight line through the temperature data for 1996 and 2015—the end points of an almost 19-year period. The trend is darn near flat. As Pruitt put it, a “leveling off.”
Amazingly, the Santer team even acknowledges that “Recent 20-year trends are smaller than most of the earlier 20-year trend values” in the 38-year satellite record. But that means there has been a slowdown in warming—a “leveling off.” Indeed, the IPCC itself discussed the warming “hiatus” in its Fifth Assessment Report (Box 9.2) and Nature Climate Change published a study documenting the slowdown in a study titled “Overestimated global warming over the past 20 years.” In a sane political climate, the only reaction Pruitt’s statement would evoke from scientists is “move along, nothing to see here.”
University of Alabama in Huntsville atmospheric scientist Roy Spencer comments on his blog:
Wow. If I only knew earlier that I could get peer-reviewed scientific papers by evaluating the silly climate claims made by politicians (Al Gore, Barack Obama, et al.) over the years. Oh, that’s right. I’m on the wrong side of the issue. The reviewers would have said, “C’mon, that’s a politician generalizing. You can’t get a peer-reviewed scientific paper out of that!”
The second thing that would be noteworthy in less dogma-ridden times is the speed with which the study was peer reviewed, published, and hailed by mainstream media. Blogger Leo Goldstein reports on WattsUpWithThat:
It passed the supposed peer review by Nature Scientific Reports in a mere 29 days: Received on March 6, Accepted on April 4, Published on May 24; praised and brandished by WaPo and ThinkProgress on the very same day.
For perspective, the median time from submission to acceptance in Nature Group publications is 129 days, and fewer than 1 percent of the last 500-plus articles published were accepted within 30 days of submission.
Third, the study does not actually rebut Pruitt’s claim that global warming has slowed down (“leveled off”). Rather, it purports to show that “Tropospheric warming trends over recent 20-year periods are always significantly larger (at the 10% level or better) than model estimates of 20-year trends arising from natural internal variability.” In other words, Santer et al. attempt to prove anthropogenic global warming is real! But Pruitt was not denying the reality of anthropogenic warming. He was just reporting observations that do not support the political imperative that science shall always find climate change to be “worse than we thought.”
More importantly, the Santer paper is an exercise in misdirection. The chief significance of the “pause” or “leveling off” is its contribution to a long-term divergence between global warming predictions and observations. The paper does not address that problem. As Spencer notes: “This [paper] then distracts attention from the real issue: that the climate models on average produce about twice as much warming as has been observed over the last few decades.”
Spencer points out another glaring omission:
The Santer paper also makes quite a bit out of the fact that warming exists in the satellite datasets at all, and that climate models do not produce that level of warming from their internal variability, suggesting an anthropogenic cause. Of course, they fail to mention that models are lousy at producing realistic multi-decadal time scale natural variability anyway, so this is hardly proof of an anthropogenic source of recent warming.