Are Midtwentieth Century Forced Changes in North Atlantic Hurricane Potential Intensity Detectable?

The impact of anthropogenic forcings on tropical North Atlantic hurricane potential intensity (PI) is evaluated in Climate Model Intercomparison Project 5 models for the period 1958–2005. Eleven models are examined, but only seven models have a forced response that is distinguishable from internal variability. The use of discriminant analysis to optimize detectability does not yield a clear, common climate change signal. Of the seven models with a significant response, one has a negative linear trend while two have a positive linear trend. The trend in PI is not even consistent among reanalyses, although this difference is not statistically significant because of large uncertainties. Furthermore, estimates of PI internal variability have significantly different variances among different reanalysis products. These disagreements between models, reanalysis products, and between models and reanalyses, in conjunction with relatively large uncertainties, highlight the difficulty of detecting and attributing observed changes in North Atlantic hurricane potential intensity. Plain Language Summary Observed temperature has been steadily increasing over the last century and much of this warming can be attributed to greenhouse gas emissions. Theoretically, the maximum intensity (or potential intensity) a hurricane can achieve depends strongly upon sea surface temperature, with warmer temperatures producing stronger storms. From this perspective, we might expect that the warming surface temperatures are driving observable changes in hurricane intensity. To this end, we analyze climate model experiments to determine if the observed changes in North Atlantic hurricane intensity can be attributed to human‐related emissions over the period 1958–2005. Of the 11 models analyzed, we find that only seven predict that hurricane potential intensity has changed in response to greenhouse gas and aerosol emissions. The change in potential intensity differs across models, with one model predicting a decreasing trend in North Atlantic hurricane potential intensity, while two models predict an increasing trend in potential intensity. Different reanalysis data sets are likewise inconsistent. These results indicate that currently we cannot attribute changes in North Atlantic hurricane intensity to human‐related forcings. It is possible that as greenhouse gas concentrations continue to increase, an unequivocal forced response in North Atlantic potential intensity may emerge in the future