New Studies on Arctic, Ice, and Jet Stream
May 3, 2016
Readers of this blog are familiar with the increasing number of studies linking the drop in Arctic sea ice to extreme weather events in the temperate latitudes, ie where a lot of people live, work, and grow food.
Above, one of my most popular vids explains, with Jennifer Francis and Jeff Masters.
Investigating the factors affecting ice melt in Greenland — one of the most rapidly changing places on Earth — is a major priority for climate scientists. And new research is revealing that there are a more complex set of variables affecting the ice sheet than experts had imagined. A recent set of scientific papers have proposed a critical connection between sharp declines in Arctic sea ice and changes in the atmosphere, which they say are not only affecting ice melt in Greenland, but also weather patterns all over the North Atlantic.
The new studies center on an atmospheric phenomenon known as “blocking” — this is when high pressure systems remain stationary in one place for long periods of time (days or even weeks), causing weather conditions to stay relatively stable for as long as the block remains in place. They can occur when there’s a change or disturbance in the jet stream, causing the flow of air in the atmosphere to form a kind of eddy, said Jennifer Francis, a research professor and climate expert at Rutgers University.
Blocking events over Greenland are particularly interesting to climate scientists because of their potential to drive temperatures up and increase melting on the ice sheet.
A team of researchers led by the University of Sheffield’s Edward Hanna used a global meteorological dataset relying on historical records to measure the frequency and strength of high pressure systems over Greenland all the way back to the year 1851. Previous analyses had only extended the record back to 1948, so the new study is able to place recent blocking events in a much larger historical context.
When the researchers analyzed the data, they found that the increase in blocking frequency over the past 30 years is particularly pronounced in the summer, the time of year when blocking events are likely to have the biggest impact on ice melt.
What’s been causing this uptick is a big source of interest for climate scientists hoping to gain a better understanding of the events affecting the vulnerable Greenland ice sheet. In the new paper, Hanna and his colleagues suggested that declines in Arctic sea ice might be playing a role — and it’s a theory that’s heavily supported by another paper just out in the Journal of Climate. That study used both observational data and computer simulations to investigate the connection between sea ice declines and atmospheric changes in the Arctic.
Diminishing Arctic sea ice is a well-established trend at this point, driven by climate change-induced warming in the region. In fact, just last month, scientists reported that the maximum extent of Arctic sea ice this past winter had reached a record low for the second year straight.