While animals are rousing themselves several weeks earlier, the plants that they normally eat are not, creating the real possibility of starvation for some of these animals...When people talk about global warming, much of the time we bring up images of stranded polar bears and extreme weather variation. Unfortunately, climate change is creating much more less-known problems, such as decreased length of hibernation. Even though scientists have some idea of just how serious the consequences of global warming will be, it's conceivable that we haven't yet realized the full extent of the problems we will be facing as a result of the world's inaction on the subject.
One alarming fact... is how much animals have altered their behavior in response to a small change in temperature.
National Geographic News: Warming Creating Extinction Risks for Hibernators