If substantial global warming continues, the North Atlantic jet stream, a fast-moving air current that circles the Northern Hemisphere, may travel northward in the next decades.
Changes in rainfall patterns in the midlatitudes, as well as a rise in droughts, heat waves, floods, and other extreme weather events across Europe and the eastern United States, might have dramatic repercussions.
Under a significant warming scenario, the jet stream could shift outside of its normal range within a few decades – by the year 2060 or so, according to a new study.
The findings were published in Proceedings of the National Academy of Sciences last week.
Scientists are debating the impact of climate change on the jet stream.
The jet stream has a significant impact on weather and climate patterns in the Northern Hemisphere, and changes in its strength or position can have far-reaching consequences around the globe.
Many experts believe that rising air temperatures will have an impact on the passage of the jet stream.
Because of the large temperature differential between the cold North Pole and the warm equator, the current exists.
The thickness of the atmosphere is affected by this temperature gradient, resulting in wavy air currents that flow from west to east across the world.
These air temps are progressively rising today.
However, not every section of the globe is warming at the same rate. Scientists predict that when some locations heat up quicker than others — particularly the rapidly warming Arctic — alterations in the atmosphere may occur, affecting air flow.
These changes, according to some researchers, may cause the jet stream to change.
However, not everyone agrees on how the jet stream might evolve – or whether climate change has already had an impact.
As it goes across the world, the jet stream tends to change around a lot, traveling north and south and bouncing up and down.
It can be difficult to tell if recent fluctuations are within typical limits or not.
The goal of the new study, coordinated by Matthew Osman of the University of Arizona, was to figure out what was going on.
Osman and his colleagues set out to follow the position of the jet stream throughout history, going back thousands of years.
They accomplished it by evaluating samples of ancient ice dug from deep inside the Greenland ice sheet using a simple scientific trick: chemical analysis.
Ice cores, as they’re known among scientists, function in a similar way to a scientific time machine.
They have a wealth of information about what the climate was like tens of thousands of years ago.
Because the jet stream has such a profound influence on regional weather and climate patterns, scientists may use this data to chart the jet stream’s evolution over time.
Researchers were able to reconstruct its position for the previous 1,250 years in this example.
They discovered that the jet stream’s location, or how far north or south it flows, varies a lot. But, thus far, any changes have remained within the range of normal variations.
But that won’t be the case for much longer.
Climate models were utilized to recreate the jet stream on a hotter planet.
The jet stream is anticipated to migrate north over time if the earth continues to warm at a rapid rate.
Indeed, the study implies that global warming has already begun to drive it poleward – it has just not yet moved outside of its typical range.
Within 40 years, though, it may have permanently established itself outside of its natural confines.
This could result in significant weather changes in the midlatitudes, especially in Europe.
The jet stream aids in the transport of rainfall systems to southern Europe, which would otherwise be dry.
If the jet stream moves north, the rainfall may be carried along with it, increasing the chances of drought.
“You’re going to be putting a lot of pressure on areas that rely on a jet stream that stays within its natural boundaries,” Osman told E&E News.
Floods and heat waves may become more common in parts of Europe.
A northward-shifting jet stream in North America might enhance warming on the East Coast and exacerbate the intensity of some extreme weather events.
“There are grounds to be positive here,” Osman argues.
Climate simulations were utilized in the current study, which assumed large greenhouse gas emissions and catastrophic warming in the future.
It’s a situation that’s already looking unlikely in the actual world, with countries all over the world attempting to reduce carbon emissions.
The jet stream is likely to travel north over time, although at a slower pace, under a more moderate warming scenario, according to Osman, which is more in line with current global climate action.
“I do want to emphasize that these are hypothetical future scenarios,” Osman cautioned. “Ultimately, we still have a lot of control over its future trajectory.”
A DISCUSSION ABOUT CLIMATE
The general position of the jet stream isn’t the only thing that climate scientists are interested in.
Climate warming, according to some experts, may make the jet stream “wavier,” forcing it to meander up and down more powerfully as it travels around the globe.
Extreme weather events can be exacerbated by jet stream waves, which can cause storm systems or heat waves to move more slowly or become trapped in place.
In their ice core examinations, Osman’s team found no information that indicated a change in waviness through time.
But, he stressed, that’s not what their method was supposed to search for.
At the same time, the position of the jet stream and its waviness may be linked.
Some scientists believe that a northward shift will result in a stronger, less wavy jet stream, according to James Screen, a climate scientist at the University of Exeter. Relocation to the south would have the opposite effect.
If the jet stream does shift north in the coming decades, he predicts decreased waviness.
It’s a point of contention among climate scientists.
According to certain research, the jet stream is already becoming weaker over time.
Some experts believe that atmospheric changes connected to rapid warming in the Arctic are to blame for these changes.
Jennifer Francis, a climate scientist at the Woodwell Climate Research Center, has spent the majority of her recent career researching Arctic warming and huge air currents like the jet stream.
According to several research, there is currently a “tug of war” going on, she told E&E News.
The jet stream may be pushed north by some effects of climate change on the atmosphere, while it may be pushed south by others.
Other researchers disagree, at least for the time being, that Arctic warming has any effect on the waviness of the jet stream.
According to a study published by Screen of the University of Exeter, any recent changes in the waviness of the jet stream are most likely natural oscillations rather than direct repercussions of Arctic warming.
The topic is still a hot topic in climate research.
The author is: Chelsea Harvey is a reporter with E&E News.