Global warming has probably made Hurricane Gustav a bit stronger and wetter, some top scientists said Sunday, but the specific connection between climate change and stronger hurricanes remains an issue of debate. Measurements of the energy pumped into the air from the warm waters — essentially fuel for hurricanes — has increased dramatically since the mid 1990s, mostly in the strongest of hurricanes, according to a soon-to-be published paper in the journal Geochemistry, Geophysics, Geosystems by Kevin Trenberth, climate analysis chief at National Center for Atmospheric Research in Boulder, Colo. Warmer water makes the surface air warmer, which means it could contain more moisture. That means more hot moist air rises up the hurricane, serving as both fuel for the storm and extra rainfall coming back down, said Peter Webster, professor of atmospheric sciences at Georgia Tech.