In 50 years, summers across most of the globe could be hotter than any summer experienced by people to date, according to a study by scientists at the National Center for Atmospheric Research (NCAR) in Boulder, Colo.

If climate change continues on its current trajectory, the probability that summers between 2061 and 2080 will be warmer than the hottest on record stands at 80 percent across the world's land areas, excluding Antarctica, which was not studied.

If greenhouse gas emissions are reduced, however, that probability drops to 41 percent.

"Extremely hot summers always pose a challenge to society," said NCAR scientist Flavio Lehner, lead author of the study. "They can increase the risk for health issues, and can also damage crops and deepen droughts. Such summers are a true test of our adaptability to rising temperatures."

The study is part of an upcoming special issue of the journal Climatic Change that will focus on quantifying the benefits of reducing greenhouse gas emissions. The research was funded by the U.S. National Science Foundation (NSF) and the Swiss National Science Foundation.