Natural and anthropogenic contributions to the hurricane drought of the 1970s–1980s

Atlantic hurricane activity experienced a pronounced lull during the 1970s and 1980s. The prevailing explanation—that anthropogenic sulfate aerosol radiative forcing cooled local sea surface temperatures—fails to capture the magnitude of the decrease. The authors propose that sulfate aerosols from Europe and North America reduced precipitation in the Sahara–Sahel, enhancing Saharan dust emissions and transport over the Atlantic. This dust further cooled the tropical North Atlantic and reduced hurricane activity. They show that Saharan dust emissions peaked in phase with regional sulfate aerosol optical thickness and Sahel drought conditions, and that dust optical depth variations alone can explain nearly half of the sea surface temperature depression in the 1970s–1980s.

Raphaël Rousseau-Rizzi, Kerry Emanuel