We’ve discussed the flawed climate risk analysis presented by Dr. Roger Pielke Jr, the non-climate expert thrown up by climate deniers in recent congressional hearings. Dr. Peilke’s ploy in his testimony was to provide a Fox and Limbaugh-friendly sound bite on video, while hiding qualifiers in his written footnotes to cover his pseudo-scientific butt. The nub of his claims were that damages due to climate change are undetectable, and would not emerge, if at all, for decades to come.
His recent hire as “climate expert” for Nate Silver’s purportedly “data driven” 538 blog proved to be such a disaster on all sides, that a chastened Silver promised to find a qualified scientist to straighten things out, and rebut his own blog.
And so he has.
Dr. Kerry Emanuel of MIT, one of the world’s best known hurricane experts, on 538:
..I’m not comfortable with Pielke’s assertion that climate change has played no role in the observed increase in damages from natural hazards; I don’t see how the data he cites support such a confident assertion. To begin with, it’s not necessarily appropriate to normalize damages by gross domestic product (GDP) if the intent is to detect an underlying climate trend. GDP increase does not translate in any obvious way to damage increase; in fact, wealthier countries can better afford to build stronger structures and to protect assets (for example, build seawalls and pass and enforce building regulations).1 A grass hut will be completely destroyed by a hurricane, but a modern steel office building will only be partially damaged; damage does not scale linearly with the value of the asset.
More seriously, a casual inspection of both graphs (normalized and non-normalized damage over time) presented by Pielke leads me to question the statistical significance of either. This is hardly surprising, since 23 years is not a very long time to detect trends in natural hazard damages, whether such trends are caused by demographics or by climate change. A 2012 study2 by London School of Economics researchers Fabian Barthel and Eric Neumayer looked at damage trends normalized by GDP, a measure they used because others are not universally available. For Germany and the United States, with 29 and 36 years of data, respectively, they detected “statistically significant upward trends in normalized insured losses from all non-geophysical disasters as well as from certain specific disaster types,” but for the globe as a whole, with 19 years of data available, they could find no significant trends.
Since the U.S. alone accounted for roughly half the insured losses over this period, the significance of the longer U.S. record and lack thereof in the shorter global record suggests that 20 years may be too short to detect significant trends. The increasing normalized trends in the U.S. were evident in convective storms, winter storms, flooding events and high temperature-related losses, and were almost statistically significant for hurricanes at the conventional 95 percent confidence level.3 In view of data like this, it’s very hard to accept Pielke’s confident assertion that “[n]o matter what President Obama and British Prime Minister David Cameron say, recent costly disasters are not part of a trend driven by climate change.”
Continue reading “Hurricanes, Risks, and Bears in the Woods”






