They pointed to a warmer atmosphere, which
carries more water vapor to worsen rainstorms, as well as to higher ocean surface temperatures, which intensify hurricanes.
On the question of hurricanes, the theoretical arguments that
more energy and
water vapor in the atmosphere should lead to stronger storms are really sound (after all, storm intensity increases going from pole toward equator), but determining precisely how human influences (so including GHGs [greenhouse gases] and aerosols, and land cover change) should be changing hurricanes in a system where there are natural external (solar and volcanoes) and internal (e.g., ENSO, NAO [El Nino - Southern Oscillation, North Atlantic Oscillation]-RRB- influences is quite problematic — our climate models are just not good enough yet to
carry out the types of sensitivity tests that have been done using limited area hurricane models run for relatively short times.
The cooler the air, the less
water vapor (humidity) it can
carry, while the warmer the air, the
more water vapor it can
carry.