If greenhouse gas emissions are not reduced by a significant level, the warming of the atmosphere can potentially drive the North Atlantic jet streams – fast-flowing air currents in the atmosphere – outside their natural range of variation, claims a study. Such change in the jet streams will drastically impact the weather on both sides of the Atlantic ocean pushing it to extreme levels in the 2060s, as per scientists.
“Extraordinary variations in the jet stream can have severe societal implications, such as floods and droughts, due to its impacts on weather patterns,” says Matthew Osman, the lead author of the study in a statement. The study was published in the September 21 issue of Proceedings of the National Academy of Sciences.
As per the scientists’ model projections of changes, the current global warming scenarios can cause a northward migration of the jet currents. Such a migration will make the southern area, which is already dry with low precipitation, drier and warmer, and the northern area wetter.
How and why jet streams change over time is not well-known, but because the impact of such changes is huge, trying to understand these changes better is important. One way of understanding the changes is to look for historical data. That is what scientists did. They dug boreholes, from 300 to 1,000 feet deep, and collected ice samples from nearly 50 sites across the Greenland ice sheet. Using the samples of ancient ice, scientists reconstructed how the windiness of the North Atlantic changed back to the eighth century. They found that till now, natural variability has largely controlled the effect of human-caused global warming in the region. However, scientists say that changes may deviate from the norm in the case of continued warming. Scientists were able to match their reconstruction with the 1374 famine in the Liberian peninsula when the reconstruction showed that the jet streams were far north. Scientists were also able to see the changes in jet streams linked with the British Isles and Ireland famines in 1728 and 1740.
“Our results serve as a warning,” adds Osman explaining that the jet stream’s trajectory is still in our control.