This year is predicted to be a bad year for ticks and Lyme disease.
About this global warming thing: our very mild winter has allowed more mice than usual to survive. The mice, in turn, host ticks. And the ticks carry diseases, especially Lyme Disease. So not only are ticks gross and disgusting, they can be dangerous as well.
Fortunately, you can get outdoors without getting ticks. Audubon provides a helpful article on avoiding tick problems while still enjoying nature.