However, in a more recent study, Curry and her team looked at records of hurricanes between 1970 and 2004, in all of the world’s ocean basins. They subjected the records to a mathematical test of mutual information, which measures the amount of information two variables share, so that if they do not overlap at all this measure would be zero. The team then looked at sea surface temperature, specific humidity, wind shear and wind variation over longitude to see what, if anything, these variables shared with the increasing number of strong storms the world over. The analysis showed that the trend of increasing numbers of strong storms only depends on sea surface temperature.