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USGS director Reilly, a former astronaut and petroleum geologist, claims the National Climate Assessment used "inaccurate modeling that focuses on worst-case emission scenarios". There are two problems with this statement. (thread) nytimes.com/2019/05/27/us/…
First, as I explain in detail in this chapters I wrote, RCP scenarios are not actually emission scenarios. They are forcing scenarios consistent with various emissions pathways. Small issue, yes; but it suggests that he doesn't understand the scenarios. science2017.globalchange.gov/chapter/4/
Second, the claim that NCA4 focused only on a "more extreme" scenario is totally false. Across the 1,600 pages of Vol 2, impacts are always quantified for a range of scenarios from extremely low to business-as-usual. Don't take my word; see for yourself: nca2018.globalchange.gov
Third (yes, there's actually three issues with one short phrase), the idea that the worst-case scenario is a product of inaccurate modeling is also false and completely contradicts the fact-based conclusion of Vol 1, Ch 4: 
If you'd like to catch up on all the mis-statements and falsehoods that have been made about the National Climate Assessment, I have an entire thread of them here!
And don't even get me started on the whole, "computer-generated models" phrase, as if climate models are some type of statistical random number generator instead of being based on very solid and well-understood physics, chemistry and biology --
In fact, the basic thermodynamics in climate models has been well-understood since the 1850s and is the same science that explains how airplanes fly and stoves heat food. Not too many politicians and political appointees deny that, do they?
Apologies and correction to this thread: the quote above comes from EPA spokesperson James Hewitt, justifying USGS’ Reilly in limiting the use of climate projections to just 20 years out. The article has it right, it was my error!
