Climate scientists disagree on the impact of the Atlantic Multidecadal Oscillation—a 25-to-40-year cycle of cooling and warming of the Atlantic Ocean—on the frequency of hurricanes. Some expect the AMO to drive cooler sea surface temperatures and fewer hurricanes in coming decades, but others do not think the AMO works this way. EAPS Professor Kerry Emanuel, who is affiliated with the MIT Joint Program, believes that another factor—air pollution—has played a significant role in reducing hurricane activity.