PNNL

Abstract

Over the past 40 years, the locations of tropical cyclones (TCs) have migrated poleward, bringing TC-related hazards to higher latitudes. A critical question is whether the poleward migration reflects a signal of long-term climate change or a temporary trend from climate variability. Here, we provide analyses and modelling evidence to show that TC latitudes are strongly modulated by a tripolar SST pattern of Pacific variability whose temporary phase trend since 1980 largely drives the observed poleward migration of TCs. The poleward migration no longer holds if the variation associated with Pacific variability is removed or when evaluated over a longer period with no phase trend in Pacific variability. Future changes in TC distribution projected by TC-permitting models present distinct spatial patterns from the past trend. Despite projection uncertainty in meridional shifts of TC latitudes, models agree on a decrease in higher-latitudinal TCs due to robust reduction in total TC number.