Dear EarthTalk: How is it that global warming could cause an increase in health problems and disease epidemics? Do we have any evidence that it is already happening? -- Jim Merrill, Provo, UT
Global warming isn't just bad for the environment. There are several ways that it is expected to take a toll on human health. For starters, the extreme summer heat that is becoming more normal in a warming world can directly impact the health of billions of people.