Assessing the Fourth “National Assessment” of Climate Change

The 1990 Global Change Research Act requires quadrennial  “Assessments” of the effects of global climate change on the U.S. The first was published in 2000, the second in 2009 (the G.W. Bush Administration chose to ignore the law), the third in 2014, and the fourth, last Black Friday.

We contributed extensive public comments on the penultimate draft of the latest Assessment, which has changed very little between the review draft and the final copy. The final version contains the same fatal flaws we noted earlier this year. It’s based upon a family of climate models that are predicting far more warming than has been occurring in the all-important tropical atmosphere. It should have used the one model (out of the 102 available runs) that actually gets things right, the Russian INM-CM4, but it relied upon the average warming produced by all 102. INM-CM4 has the least warming of all of them, but doing the right thing—using the one that works—would have pretty much gutted climate change as a serious issue.

These reports take several years to produce, and the current one was largely a product of the Obama Administration. If there’s a Trump Administration when the next one is scheduled (2022), it is likely to be very different. Why the current regime just didn’t do as Bush did and simply elide the 1990 law is probably so it will get another crack at it in 2022.

Our lengthy technical comments still apply.