Before 1980, excessively hot summers were practically non-existent. More recently, found a new study, summers that averaged 3.3 degrees Fahrenheit hotter than normal have become common – covering about 10 percent of land area around the globe each year – up from an average of just a few tenths of a percent in the 1950s, 60s, and 70s. In some recent years, super-hot summers have struck as much as 20 percent of the Northern Hemisphere.

Statistically, the pattern is too extreme to be considered a result of chance, found a new study, which pointed a finger directly at global warming as the underlying cause of the recent spike in extra-hot summers.

With projected warming over the next 50 years, the study predicted that summers averaging 5.5 Fahrenheit above normal will happen regularly. In a decade, nearly 17 percent of the globe will likely be experiencing scorching summers each year.

“The problem is that there’s always this caveat when people say, ‘Well, you can’t blame any individual event on global warming,’” said James Hansen, a climate scientist at the Goddard Institute for Space Studies in New York.