WASHINGTON (AP) – Daily weather patterns have changed in recent decades, making eastern North America, Europe and western Asia more prone to nastier summer heatwaves that go beyond global warming, a new study finds.
A team of climate scientists at Stanford University looked at weather patterns since 1979 and found changes in frequency and strength in parts of the world, according to a study published in the journal Nature on Wednesday. These are the types of weather patterns with stationary high and low pressure systems that you see on weather forecasts, which is different than gradual warming from man-made climate change.
The team studied the kind of upper air patterns that “sort of amplifies the warming trend,” said study lead author Daniel Horton.
The study doesn’t attempt to explain why these changes are happening. But in general they fit a theory that has gained momentum in climate science that says melting sea ice in the Arctic has sometimes altered the way the jet stream flows, contributing to extreme weather like Superstorm Sandy, outside experts said.
In many cases, including the eastern U.S. and western Asia in summer, some of these changes have become even more noticeable since 1990, the same period in which Arctic sea ice has gone through a rapid decline, the study found.