A new study published in the journal Science suggests that a warming arctic is interfering with the jet stream causing a diminishing of summer storms. The decline in storm activity, in turn, is leading to increased summer heat waves.

“When the great air streams in the sky above us get disturbed by climate change, this can have severe effects on the ground. While you might expect reduced storm activity to be something good, it turns out that this reduction leads to a greater persistence of weather systems in the Northern hemisphere mid-latitudes. In summer, storms transport moist and cool air from the oceans to the continents bringing relief after periods of oppressive heat. Slack periods, in contrast, make warm weather conditions endure, resulting in the buildup of heat and drought,” said lead-author Dim Coumou, of the Potsdam Institute for Climate Impact Research in a statement.

The research supports some highly controversial theories that have been circulating since 2012.

“That’s what Rutgers University’s Jennifer Francis has argued in a series of papers going back to 2012 — but there has been quite a lot of criticism. Several distinguished climate researchers even wrote to Science magazine in early 2014 contesting the notion, saying that ‘we we do not view the theoretical arguments underlying it as compelling,’” said Chris Mooney of the Washington Post.

According to the Potsdam researchers, most previous research on storm activity focused on winter weather activity. Winter storms are normally the most damaging. However, looking at global data, winter storm activity remains largely unchanged. Some regions may experience unusual frequency or intensity of storms, summer is another story.

The researchers examined weather station and satellite data and found a clear and consistent decrease in average summer storm activity. This could mean a decrease in frequency, a decrease in intensity or both.

The team looked specifically at synoptic eddies, a specific type of turbulence and calculated the total energy they held based on their wind speed.

The energy generated is a measure of the “interplay between intensity and frequency of high and low pressure systems in the atmosphere”. This intensity was found to have dropped by ten percent since 1979.

“Unabated climate change will probably further weaken summer circulation patterns which could thus aggravate the risk of heat waves. Remarkably, climate simulations for the next decades, the CMIP5, show the same link that we found in observations. So the warm temperature extremes we’ve experienced in recent years might be just a beginning,” said co-author Jascha Lehmann.

According to the paper, the Arctic, which is warming twice as fast as most other regions on Earth could be driving the changes in circulation. As the sea ice cover diminishes, the region takes up less heat and the dark water reflects less light back into space.

Normally it is the difference between the cold arctic and the warm air that drives air movement, because this difference is less the jet stream is weakened and storm activity diminishes.

“From whichever angle we look at the heat extremes, the evidence we find points in the same direction. The heat extremes do not just increase because we’re warming the planet, but because climate change disturbs airstreams that are important for shaping our weather. The reduced day-to-day variability that we observed makes weather more persistent, resulting in heat extremes on monthly timescales. So the risk of high-impact heat waves is likely to increase,” said Coumou.