Dear Alaska: We Have Your Air. Please Come Pick it Up. And Bring us Back Ours. Love, Eastern US.

February 23, 2015

maine0223msall

Above, the Climate Reanalyzer image for North America temperature anomalies. Currently minus 17° F, or minus 27°C, here where I am.
UPDATE: and whoa, baby!! that’s freaking cold out there. I was just out shooting the sunrise. Still counting my fingers and toes, and my iphone is giving me a temperature error I’ve never seen before.

Note above the cold blues and purples over eastern North America, and the bloody reds flooding the arctic.

Jennifer Francis in Scientific American:

Everyone loves to talk about the weather, and this winter Mother Nature has served up a feast to chew on. Few parts of the US have been spared her wrath.

Severe drought and abnormally warm conditions continue in the west, with the first-ever rain-free January in San Francisco; bitter cold hangs tough over the upper Midwest and Northeast; and New England is being buried by a seemingly endless string of snowy nor’easters.

Yes, droughts, cold and snowstorms have happened before, but the persistence of this pattern over North America is starting to raise eyebrows. Is climate change at work here?

Wavier jet stream
One thing we do know is that the polar jet stream—a fast river of wind up where jets fly that circumnavigates the northern hemisphere—has been doing some odd things in recent years.

Rather than circling in a relatively straight path, the jet stream has meandered more in north-south waves. In the west, it’s been bulging northward, arguably since December 2013—a pattern dubbed the “Ridiculously Resilient Ridge” by meteorologists. In the east, we’ve seen its southern-dipping counterpart, which I call the “Terribly Tenacious Trough.” (See picture, below.)

francis_sciam

These long-lived shifts from the polar jet stream’s typical pattern have been responsible for some wicked weather this winter, with cold Arctic winds blasting everywhere from the Windy City to the Big Apple for weeks at a time.

We know that climate change is increasing the odds of extreme weather such as heatwaves, droughts and unusually heavy precipitation events, but is it making these sticky jet-stream patterns more likely, too? Maybe.

The jet stream is a dastardly complex creature, and figuring out what makes it tick has challenged atmospheric scientists since it was discovered about 75 years ago. Even more elusive is figuring out how climate change will affect it.

Jet streams exist because of differences in air temperature. In the case of the polar jet stream, which is responsible for most of the weather we experience around the middle-latitudes of the northern hemisphere, it’s the cold Arctic butting against warmer areas to the south that drives it. (A more in-depth explanation can be found here.) Anything that affects that temperature difference will affect the jet stream.

francis_sciam2

This is where climate change comes in: the Arctic is warming much faster than elsewhere. That Arctic/mid-latitude temperature difference, consequently, is getting smaller. And the smaller differential in temperatures is causing the west-to-east winds in the jet to weaken.

Strong jets tend to blow straight west to east; weaker jets tend to wander more in a drunken north/south path, increasing the likelihood of wavy patterns like the one we’ve seen almost non-stop since last winter.

When the jet stream’s waves grow larger, they tend to move eastward more slowly, which means the weather they generate also moves more slowly, creating more persistent weather patterns.

At least, that’s the theory. Proving it is not easy because other changes are happening in the climate system simultaneously. Some are natural fluctuations, such as El Niño, and others are related to increasing greenhouse gases.

We do know, however, that the Arctic is changing in a wholesale way and at a pace that makes even Arctic scientists queasy. Take sea ice, for example. In only 30 years, its volume has declined by about 60%, which is causing ripple effects throughout the ocean, atmosphere, and ecosystem, both within the Arctic and beyond. I’ve been studying the Arctic atmosphere and sea ice my entire career and I never imagined I’d see the region change so much and so fast.

‘Stuck’ weather patterns
To study the effects of Arctic change on weather patterns, we have good measurements of atmospheric temperatures and winds going back to the late 1970s, when satellites started providing data, and pretty good measurements back to the late 1940s.

My colleagues and I have been using this information to measure the waviness of the jet stream and whether it is behaving differently since the Arctic started its rapid warm-up about 20 years ago. Because the upper atmosphere is such a cacophony of swirling winds, however, measuring changes in the jet stream’s waviness is tricky, as it’s not a metric that scientists have traditionally used.

Our challenge, then, is to find new methods to measure waviness and determine whether any changes we find are related to rapid Arctic warming, to some other change in the climate system, or to just random chance. While the story is still in early days, the plot is thickening.

Several groups around the globe, including my colleagues and me, are trying to understand the linkages between rapid Arctic warming and changes in weather patterns.

A number ofrecentstudies have found what appears to be a solid connection between sea-ice loss in an area north of western Russia during the fall and a rash of abnormally cold winters in central Asia. The loss of sea ice favors a northward bulge in the jet stream, which strengthens surface high pressure to the east. That shift pumps cold Arctic air southward into central Asia.

Other studies suggest that Arctic warming in summer leads to a split jet stream—or two separated rivers of wind—which tends to trap the waves. Those stationary waves cause weather conditions to remain “stuck” for long periods, increasing the likelihood of extreme heat waves, droughts and flooding events in Eurasia and North America.

Iditarod Dogsled race, Alaska, 2014. Because mushers were outraged at conditions last year, organizers have moved the course northward in 2015.

Iditarod Dogsled race, Alaska, 2014. Because mushers were outraged at conditions last year, organizers have moved the course northward in 2015.

Our own new work, published last month in Environmental Research Letters, uses a variety of new metrics to show that the jet stream is becoming wavier and that rapid Arctic warming is playing a role. If these results are confirmed, then we’ll see our weather patterns become more persistent.

In other words, Ridiculously Resilient Ridges and Terribly Tenacious Troughs may become the norm, along with the weather woes they cause.

Jennifer Francis receives funding from the National Science Foundation and NASA. She is a member of the American Meteorological Society, American Geophysical Union, Association for Women in Science and the Union of Concerned Scientists.

This week I’m running down to Ann Arbor, to the University of Michigan’s School of Atmopheric, Oceanic and Space Science, where I hope to find out more.

Meanwhile, here’s my piece from last year’s Polar Vortex, which still applies.

UPDATE:

LiveScience:

As if the outdoors weren’t harsh enough with Boston buried under ungodly amounts of snow and the rest of the Northeast unable to shake the bitter cold, more winter weather is on the way. So what’s behind this extreme chill?

Parts of the United States are expected to have historic lows this week, as temperatures in the Southeast, Mid-Atlantic and central Appalachians may drop to the coldest they’ve been since the mid-1990s, according to the National Weather Service (NWS).

“Get ready for an even more impressive surge of Arctic air later this week as another cold front drops south from Canada,” the NWS said in a statement.

 

 

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5 Responses to “Dear Alaska: We Have Your Air. Please Come Pick it Up. And Bring us Back Ours. Love, Eastern US.”

  1. Andy Lee Robinson Says:

    That pattern is seriously messed up – it looks like we have moved the Pole!

  2. Gingerbaker Says:

    I suppose we can expect truly kooky weather for hundreds of years to come – until most of the ice melts?


  3. […] OO Dear Alaska: We Have Your Air. Please Come Pick it Up. And Bring us Back Ours. Love, Eastern US. […]


  4. […] OO Dear Alaska: We Have Your Air. Please Come Pick it Up. And Bring us Back Ours. Love, Eastern US. […]


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