Hurricanes and rising global temperatures

Theoretical and modeling assessments consistently point toward an increase in hurricane intensity with global warming (1⇓–3). For the North Atlantic, the annual number of the most intense hurricanes has been predicted to increase by more than 50% for each 1-°C increase in surface temperatures (2, 4). However, there is no consensus on whether current hurricanes have responded to the substantial global warming that has already occurred (2, 3); some studies find a substantial increase in intense systems (5⇓–7) whereas others find none (8, 9). This presents a conundrum: if we cannot find a current signal, how can we interpret, or even accept, the future projections? A major issue has been the heterogeneity of most of the available hurricane data, which contain inherent trends in observing and analysis methodologies that are difficult to isolate. This masks any real trends and has generated substantial debate on how to interpret information that may appear to have substantial inherent contradictions. In PNAS, Grinsted et al. (10) provide a valuable contribution to this debate by way of a homogeneous hurricane proxy record. They synthesize storm-surge data into an index that relates to landfalling hurricanes along the US coast. The method has limitations; for example, the index …