Despite the USGCS report, there is indeed evidence that hurricanes are getting more intense.
Up to now, intensity level of a hurricane was measured by the top intensity it achieved. However-there is a flaw in this system: no attempt was made to factor in
how long it kept this intensity.
So Hurricane A, which kept it's top intensity for a few hours, measures equally to Hurricane B, which kept it's top intensity for a day or more. Needless to say, Hurricane B has for more potential for destruction.
That situation has now been rectified.
Famous MIT climatologist Kerry Emanuel has measured the intensity of hurricanes in the Atlantic and Pacific over decades and has reached the startling conclusion that the total power dissipated in these hurricanes today is
twice as much as it was thirty years ago.
Kerry Emanuel wrote: ... the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone, and show that this index has increased markedly since the mid-1970s. This trend is due to both longer storm lifetimes and greater storm intensities. I find that the record of net hurricane power dissipation is highly correlated with tropical sea surface temperature, reflecting well-documented climate signals, including multi-decadal oscillations in the North Atlantic and North Pacific, and global warming.
Source.
The conclusions of the USGCS were not calculated with the total power dissipation of the hurricanes in question. Only the peak intensity. This is the reason for the discrepancy between it's conclusions of "more intense precipitation events" but not more numerous or intense hurricanes.
Here is MIT's Kerry Emauel's chart showing both tropical seas surface temperatures, (solid line), and the Power Dissipation, (PDI), of Atlantic hurricanes. Note the upward trend, as well the correlation between increased tropical sea surface temperature and the increasing power of hurricanes.
