One study conducted by the University of Tennessee attempts to establish a more statistically significant history of Hurricanes. Modern hurricane tracking and record-keeping with modern instruments only dates back to around the time of World War II (though there are spotty and less accurate records going back to the 16th and 17th century.)
Scientists are using the “records” stored in tree rings to determine when and where hurricanes made landfall as far back as 1420. With this data scientists can more accurately determine if the current rise in the number of hurricanes is part of a natural cycle or tied, at least partially, to human activity
Read the full report here
The second report deals more with the cause in the apparent rise in the intensity of hurricanes. Work done at the National Center for Atmospheric Research in Boulder, CO, and Lawrence Livermore National Laboratory in Livermore, CA have studied the relationship of climate and hurricanes using 22 different climate models at 15 institutions around the world.
Their findings are reported here