Hurricanes - caused by global warming?

One of the biggest "pieces of evidence" I have heard from those who say global warming is man made is that the number of natural disasters such as hurricanes has been increasing over the past few decades. So my question is, does a slight temperature change really affect what causes a hurricane or not?

Well to answer this question, we first must look at what causes a hurricane to form. A hurricane is formed when a low pressure system travels over a warm body of water, normally in the tropics. So it would make sense that warmer temperature would increase the chance of a hurricane forming, since it happens over warm waters; and in fact it probably does increase the chance slightly.

However, this brings up another question. Why don't hurricanes form even more often than they do if this is all they need to form? Well, the hurricanes will only form when the heat is there long enough to build up to be strong enough to cause a hurricane. Usually, most of the heat in the areas is carried away by the wind shear of storms, but when there is little wind shear to blow away the heat, it is allowed to build up, and later cause a hurricane. So it doesn't matter how warm the water is (to a reasonable point); if the heat is not allowed to build up, no hurricane will be able to form.

Also, according to what Mr. Hosler (founding member of the EPA) told me three years ago when I interviewed him, there were so many conditions that had to be met for a hurricane to form that he doubted the idea that an increase in temperature would affect the chance of hurricanes at all.

So to conclude, the conditions for hurricanes to form are so great in number, such as lot's of heat being able to build up, that it is unlikely that the increased number of hurricanes is affected much if at all by increased global temperature.

sources used:
http://www.macmillanmh.com/socialstudies/2003-5/hurricanekatrina/hurricaneformation.html
http://www.weatherquestions.com/What_causes_hurricanes.htm
My interview three years ago with Charles Hosler