Research Article

Dominant effect of relative tropical Atlantic warming on major hurricane occurrence

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Science  16 Nov 2018:
Vol. 362, Issue 6416, pp. 794-799
DOI: 10.1126/science.aat6711

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Warm water and big winds

The 2017 North Atlantic hurricane season was highly active, with six major storms—nearly two standard deviations above the normal number. Three of those storms made landfall over the Gulf Coast and the Caribbean, causing terrible damage and loss. Why was the season so fierce? Murakami et al. used a suite of high-resolution model experiments to show that the main cause was pronounced warm sea surface conditions in the tropical North Atlantic. This effect was distinct from La Niña conditions in the Pacific Ocean that were involved in other years. It remains unclear how important anthropogenic forcing may be in causing such increased hurricane activity.

Science, this issue p. 794

Abstract

Here we explore factors potentially linked to the enhanced major hurricane activity in the Atlantic Ocean during 2017. Using a suite of high-resolution model experiments, we show that the increase in 2017 major hurricanes was not primarily caused by La Niña conditions in the Pacific Ocean but rather triggered mainly by pronounced warm sea surface conditions in the tropical North Atlantic. Further, we superimpose a similar pattern of North Atlantic surface warming on data for long-term increasing sea surface temperature (a product of increases in greenhouse gas concentrations and decreases in aerosols) to show that this warming trend will likely lead to even higher numbers of major hurricanes in the future. The key factor controlling Atlantic major hurricane activity appears to be the degree to which the tropical Atlantic warms relative to the rest of the global ocean.

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