Future global warming scenarios, take 2.

Abstract

In his Letter “Future global warming scenarios” (16 Apr., p. 388), W. S. Broecker critiques our recent study for the Department of Defense on the national security implications of abrupt climate change ([1][1]). We admire Broecker and his work, which importantly informed the scientific underpinning of the study, and although we agree with the substance of his comments on the science of climate change, his critique does not accurately reflect the content of the report—or its intent. First, we make no predictions. As our opening paragraph explicitly states: “The purpose of this report is to imagine the unthinkable—to push the boundaries of current research on climate change so we may better understand the potential implications on United States national security… We have created a climate change scenario that although not the most likely, is plausible, and would challenge United States national security in ways that should be considered immediately.” Broecker is correct in asserting that the most likely scenario is one of regional climate change (locations uncertain) many decades from now. But that would have little impact on today's strategic planning for national security. That is why we examined the plausibility of a low-likelihood, near-term abrupt climate change scenario across all the major geographies. Why should abrupt climate change matter to the Department of Defense? Because thinking the unthinkable is fundamental. In 2000, the senior writer of this report led one of the teams that explored “National Security in the 21st Century” with the Hart-Rudman Commission. The Commission's report, published in the summer of 2001, concluded that a major terrorist attack on U.S. soil was likely in the next quarter century and that we were ill prepared to either detect or stop it. At the time, this was considered a low-probability event; today, the government is under considerable fire for not seriously considering such scenarios. Our climate change study was conducted and shared in that spirit. It was not an attempt to do climate science or influence climate policy. But its conclusions strongly suggest that it is in our national security interests to increase support for climate science so that we can gain better insight into the timing, nature, and likelihood of abrupt climate change. 1. 1.[↵][2]1. P. Schwartz, 2. D. Randall , “Abrupt climate change,” report prepared by Global Business Network (GBN) for the Department of Defense, available at [www.gbn.org/ArticleDisplayServlet.srv?aid=26231][3]. [1]: #ref-1 [2]: #xref-ref-1-1 View reference 1. in text [3]: http://www.gbn.org/ArticleDisplayServlet.srv?aid=26231