In summer, however, the analysis of observational data coming from weather stations and satellites reveals a clear decrease in the average storm activity. This means a reduction in either frequency or intensity, or of both. The scientists studied a specific type of turbulences known as synoptic eddies, and calculated the total energy of their wind speeds. This energy, which is a measure for the interplay between intensity and frequency of high and low pressure systems in the atmosphere, dropped by roughly one tenth since 1979.
"Unabated climate change will probably further weaken summer circulation patterns which could thus aggravate the risk of heat waves," says co-author Jascha Lehmann "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."