Category 5 is currently the highest hurricane category, but many experts suggest that as hurricanes become more powerful due to climate change, a Category 6 may be needed. "There is strong agreement that the frequency and intensity of major tropical cyclones — Category 3 and above — are likely to increase as a result of climate change," says Ali Sarhadi, assistant professor in the School of Earth and Atmospheric Sciences. "This is driven by rising ocean temperatures, which provide more thermal energy to fuel tropical cyclones, and the increased capacity of a warmer atmosphere to hold moisture, leading to heavier rainfall during the landfall of these storms."