With average global temperatures expected to rise more than 3.6 degrees Fahrenheit (2 degrees Celsius) over the coming decades, a new report from a leading U.S. environmental group warns that future summers are likely to be filled with more misery, from more prolific poison ivy and biting insects to worsened air and water quality and impacts on tourism.

"Summer has always been a time many people look forward to, but climate change is causing more and more threats that we need to be mindful of," says Kim Knowlton, a co-author of the new report and senior scientist with the New York-based Natural Resources Defense Council (NRDC).

"We see more than ever that climate change is affecting people's health here and