The Global Change Research Act of 1990 mandates that the U.S. Global Change Research Program deliver a report to Congress and the President on global change, human-induced and natural, at least every four years. The Fourth National Climate Assessment (NCA4) is the latest report to fulfill this mandate. Volume I came out in 2017 and presented the foundational science of climate change. Volume II was released on November 23, 2018 and focuses on the observed and projected impacts of climate change in the US, with special consideration given to risk reduction.

Although Volume II (heretofore NCA4-II) is around 1600 pages long and would thus take some time to read, news media outlets were quick to react to the report’s release. CNN, in particular, was on it:

Climate change will have dire consequences for US, federal report concludes by Jen Christensen and Michael Nedelman, CNN; 3:15 PM ET, Fri November 23, 2018.

But apparently someone at CNN didn’t think that was strong enough, so the headline was changed a few minutes later:

Climate change will shrink US economy and kill thousands, government report warns by Jen Christensen and Michael Nedelman, CNN; Updated 3:53 PM ET, Fri November 23, 2018.

Vox dilly-dallied a full day before coming out with its own take:

3 big takeaways from the major new US climate report: Climate change is here, it’s expensive, and it’s deadly, according to a dire new report by Umair Irfan; Nov 24, 2018.

While I’m not going to pretend I read the whole thing, I did a thorough skimming of some key sections: Executive Summary, Overview, The Midwest, Reducing Risks Through Adaptation Actions and Reducing Risks through Emissions Mitigation. And I hereby pronounce: CNN and Vox did not even come close to doing their due diligence on this report. A few points from my time-consuming perusal:

NCA4-II did not use ‘dire’ or ‘grim’ even once in the sections I read.

NCA4-II did not say anything “will” happen. The report’s predictions are tentative and carefully hedged with qualifiers, e.g., “without substantial and sustained global mitigation and regional adaptation efforts, climate change is expected to cause” x, y, and z.

CNN and Vox zeroed in on the most alarming predictions in NCA4-II, which were part of an analysis that strategically* assumed a worst-case scenario of extreme global warming without significant adaptation.

Specifically, the estimates of economic damage and mortality cited by CNN and Vox were based on an “RCP8.5” scenario**, under which global temperatures could increase as much as 5.4°C by 2100 - over three times the 1.5°C temperature goal set by the Paris Agreement - with the assumption that the US would do diddly-squat about it. No improvements in farming or road construction or coastal protection. No public health initiatives to reduce vulnerability to the warming climate. Nothing. Hardly a realistic assumption.

As NCA4-II points out repeatedly, a lot is already being done in the US to lessen the impact of climate change. Of course a lot more needs to be done, but we’re on the right track.

Next: A few examples of what is being done to lessen the impact of climate change, per NCRA-II.

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* Worst-case scenarios may not be realistic but can still be useful for problem-solving. For instance, the worst-case of RCP8.5 challenges planners to come up with ways to reduce costs, damage, and casualties, which are then incorporated into computer models to see what difference they would make. As noted in Volume I of the Fourth National Climate Assessment (EPA, 2017): “[under] RCP8.5, well-timed adaptation could reduce over 75% of the cumulative impacts to coastal properties, roads, and the rail system in the U.S., resulting in hundreds of billions of dollars in cumulative benefits this century.” 

** RCP stands for Representative Concentration Pathway, a greenhouse gas concentration trajectory. See van Vuuren (below) for more.

References:

EPA, 2017: Multi-model Framework for Quantitative Sectoral Impacts Analysis: A Technical Report for the Fourth National Climate Assessment. EPA 430‐R‐17‐001. U.S. Environmental Protection Agency (EPA), Washington, DC, 271 pp. URL

USGCRP, 2018: Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA. doi: 10.7930/NCA4.2018. https://nca2018.globalchange.gov/

van Vuuren, D. P., J. Edmonds, et al. (2011). "The representative concentration pathways: an overview." Climatic Change 109(1): 5. https://link.springer.com/article/10.1007/s10584-011-0148-z