Heat waves threatened people and crops across the globe throughout the summer of 2018, according to Nexus Media, researchers have concluded that humans are to blame.

Climate researcher Martha Vogel and her colleagues at ETH, a science technology, engineering and mathematics university in Zurich, analyzed heat waves from last summer to determine their cause. The team focused on cities and farming regions in the Northern Hemisphere, although the heat affected people worldwide.

The researchers began by collecting news stories of heat waves in 2018. They found reports of wildfires in Canada and the United States, as well as stories on withering crops across the European Union. Indiana wasn’t safe from the heat either, with numerous heat advisories issued throughout the summer and increased pressure on crops due to the heat.

Vogel and her team then looked at the last 60 years of temperature data from the regions studied to see how many suffered extreme heat at any one time. Between May and July of 2018, heat waves simultaneously affected one-fifth of the area studied.

The researchers used climate models to predict the likelihood of such heat waves historically and in today’s climate. They found that simultaneous heat waves of this size and ferocity did not exist in the historical simulation, only appearing in the simulation of today’s climate.

“The occurrence of such extraordinary global-scale heat waves did not occur in the past, and cannot ‘otherwise’ be explained,” Vogel said.

The growing trend of frequent, severe heat waves poses threats to public health in the form of wildfires and the protection of infrastructure like roads and railways. It also threatens the agricultural industry and may cause instability in global food markets.

To protect themselves from heat waves, Hoosiers should follow the Red Cross guidelines. The organization emphasizes staying hydrated, wearing loose-fitting, lightweight, light-colored clothing and taking frequent breaks if you must work outdoors.