That paper is out of date Christopher. We've had several peer-reviewed studies since then showing that we CAN now definitively link them to climate change, and one specifically showing hurricane severity being increased by climate change  - came out just last week. 

More-over the IPCC reports is NOT a scientific document or study, it's a report ON scientific studies prepared for politicians and layman to tell them what they need to know and how to prioritise their responses.  That is not a diss against it, such reports are critical  -it's useless to publish scientific results that only other scientists can fully understand if you don't also communicate their essence to the public and it's governments. 
But it's that latter bit -and when it came out (a few years ago) we didn't yet have the means to make definitive links like this, which it was honest about. We do now. Science advances faster than you think.