Researchers at the University of Minnesota claim that the historical increase of farmland could have increased the severity of storms across the state.

Vast swathes of the countryside of Minnesota have been transformed from natural prairie to farmland over the past 150 years.

According to biometeorologist Professor Tim Griffis, evaporation rates are about 40 to 50 percent higher over maize fields than they are over natural prairie, which significantly increases the humidity.

Professor Griffis told Minnesota Public Radio News that so much of Minnesota is now farmland that there has been a noticeable increase in the local humidity.

Sweating, one of the key cooling mechanisms of the body, can only work if the water that is excreted through the skin evaporates. If the humidity is high, the evaporation rate drops and the body struggles to cool down.

This means that Minnesota’s hot summers would have been a lot more tolerable 150 years ago, when the landscape was still in its natural state.

However, the increased humidity can also have other, more dangerous, implications, as moisture is a key ingredient in the development of thunderstorms.

Professor Griffis believes that an increase in humidity could have increased the severity of storms across the region.

“When you load the atmosphere with water vapour, you increase the chances of having more intense precipitation,” he said.

This is of particular concern to a country that has some of the world's most intense thunderstorms in the world. The storms often bring about large hail, torrential rains and tornadoes.

Minnesota is on the far northern tip of Tornado Alley, an area of the United States where tornadoes are most frequent.

As climate change continues to take hold and temperatures continue to rise, it is likely that the evaporation rate will climb even further.

This would mean that summer days would become hotter and more humid, night time temperatures would be higher and thunderstorms would become more severe - changes Minnesota locals aren't likely to relish.

Source: Al Jazeera and agencies