Enhanced intensity of global tropical cyclones during the mid-Pliocene warm period

Abstract

<p id="d6547735e255">To better understand how tropical cyclones (TCs) may respond to future warming, we explore the behavior of TCs during the mid-Pliocene warm period (∼3 Ma), which shares characteristics of projected warmer climate. Our TC-permitting numerical simulations predict enhanced global-average peak TC intensity, longer duration, increased power dissipation, and a poleward migration of the location of peak intensity during the mid-Pliocene, although there are regional differences in the magnitude and statistical power of the climate/TC relationships. Our results share similarities with global TC changes observed during recent global warming and in most future projections and provide a window into the potential TC activity that may be expected in a warmer world. </p><p class="first" id="d6547735e258">Given the threats that tropical cyclones (TC) pose to people and infrastructure, there is significant interest in how the climatology of these storms may change with climate. The global historical record has been extensively examined, but it is short and plagued with recurring questions about its homogeneity, limiting its effectiveness at assessing how TCs vary with climate. Past warm intervals provide an opportunity to quantify TC behavior in a warmer-than-present world. Here, we use a TC-resolving (∼25 km) global atmospheric model to investigate TC activity during the mid-Pliocene warm period (3.264−3.025 Ma) that shares similarities with projections of future climate. Two experiments, one driven by the reconstructed sea surface temperatures (SSTs) and the other by the SSTs from an ensemble of mid-Pliocene simulations, consistently predict enhanced global-average peak TC intensity during the mid-Pliocene coupled with longer duration, increased power dissipation, and a poleward migration of the location of peak intensity. The simulations are similar to global TC changes observed during recent global warming, as well as those of many future projections, providing a window into the potential TC activity that may be expected in a warmer world. Changes to power dissipation and TC frequency, especially in the Pacific, are sensitive to the different SST patterns, which could affect the viability of the role of TCs as a factor for maintaining a reduced zonal SST gradient during the Pliocene, as recently hypothesized. </p>