This is the essence of the IPCC Assessment Report 4 (WG1 chapter 3) executive summary on hurricanes:
Intense tropical cyclone activity has increased since about 1970. … Globally, estimates of the potential destructiveness of hurricanes show a significant upward trend since the mid-1970s, with a trend towards longer lifetimes and greater storm intensity. … These relationships have been reinforced by findings of a large increase in numbers and proportion of hurricanes reaching categories 4 and 5 globally. … numbers of hurricanes in the North Atlantic have also been above normal (based on 1981–2000 averages) in 9 of the last 11 years, culminating in the record-breaking 2005 season.
In reality, hurricanes, in both strength and in frequency, have been decreasing over the past four years. Ryan Maue of the Center for Ocean-Atmospheric Prediction Studies (COAPS) at Florida State University, a hurricane researcher, has shown that “global and Northern Hemisphere tropical cyclone activity remains near 30-year historical lows — three years in a row now of considerably below-average activity globally.”
The decrease is not only in the number of hurricanes, but also in the total energy (ACE) of hurricanes, both in the Atlantic and worldwide, as a graph of hurricane energy vs. time shows:
Go check it out, some real interesting charts on the data
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