Warmer waters and more hurricanes

Ocean heat content and water vapor have both increased over the past several decades. This is because of human activities such as the burning of fossil fuels and the clearing of forests, which have significantly elevated carbon dioxide (CO2) levels in the atmosphere.
CO2 and other heat-trapping gases act like an insulating blanket that warms the land and ocean and increases evaporation. As the temperature of oceans rises, so will the probability of more frequent and stronger hurricanes.Warmer surface waters generate more powerful and destructive storms.

In a tropical cyclone, air rotates inward to the center (or eye), then rises to higher altitudes. As warm, moist air rises, the air cools and condenses to rain, releasing heat. This cycle of evaporation and condensation powers the storm. Adapted from a figure of courtesy of NOAA.