Study Links Arctic Melting, Extreme Weather
WASHINGTON — As ice at the North Pole disappears at an alarming rate, some researchers are finding a link between that phenomenon and recent bouts of extreme weather. A new study suggests rapid warming in the Arctic may be altering weather patterns across the Northern Hemisphere, but skeptics say the case is far from proven.
In the past three decades, ice around the North Pole has declined by half, according to Rutgers University climate scientist Jennifer Francis.
“If you take into account the thickness as well, we’ve lost almost three-quarters of the volume of the sea ice. So, it’s just an unbelievable amount of change that’s going on in the Arctic,” said Francis.
At the same time, the Northern Hemisphere has seen some unbelievable weather in the last decade, including record-breaking heat waves and droughts in North America and Europe, and devastating floods in East Asia, to name a few.
The question is: are they connected?
Francis and colleagues went back through 30 years of weather data and measurements of Arctic ice and snow cover in northern latitudes. Their findings did show a correlation between the two.
“What we found was, when there was less ice or less snow in any given year during the summertime, that that was more likely to occur at the same time as the occurrences of heat waves,” said Francis.
They published their findings in the journal Nature Climate Change. Francis said the loss of ice and snow is affecting the high-altitude winds called the jet stream, which push weather patterns around the Northern Hemisphere.
The jet stream is driven by the difference in temperature between the Arctic and the temperate zones. The bigger the difference, the faster the jet stream flows.
However, Francis notes that the Arctic is warming twice as fast as the rest of the planet, which will lessen the effect of the jet stream.
“If we warm the arctic faster, then it’s decreasing the temperature difference and causing the jet stream to get weaker,” explained Francis.
A weaker jet stream is wavier, she says. Think of a stream flowing down a mountain; the steeper the height difference, the faster and straighter it runs. On level ground, that stream can meander.
As the jet stream meanders, it pulls hot weather up from the tropics or cold weather down from the Arctic.
“As these waves get larger, they tend to move more slowly from west to east. So, as they do that, whatever weather they’re causing down at the surface also changes more slowly,” said Francis.
The result is that heat waves, cold snaps and rainstorms last longer. However, Francis is quick to warn against drawing conclusions too hastily.
“It could be true, but at the moment I don’t think the evidence is there to really strongly argue the case,” cautioned Francis.
University of Exeter climate scientist James Screen is one of those not convinced.
Screen says the new study only shows a few scattered areas of the globe where the link between sea ice loss and heat waves are significant, according to mathematical tests.
“Which implies either that the relationship is quite weak, or actually, it could be interpreted that the relationship doesn’t exist at all,” said Screen.
Screen also pointed out that researchers have just begun to study the impact of Arctic melting on global weather.
“It’s a hot topic, but there’s a lot of work to be done. The jury’s still out on whether Arctic ice is influencing weather extremes,” said Screen.
It is an important area of research, experts say. As greenhouse gas emissions continue to climb, there is more Arctic melting to come. VoA