OUT OF BALANCE
It has been our concern for some time here at the Central Rockies Progressive, and during our previous incarnation as the Alaska Progressive Review, with what we have been observing in the global climate system. Namely that faster greenhouse-gas induced warming in the Arctic versus the mid-latitudes (due to decreases overall in snow/ice cover allowing greater amounts of incoming solar radiation to add heat to the land surfaces and Arctic Ocean) is leading to big changes in the Northern Hemisphere. Causing the major troughs and ridges in the jet stream flow to amplify, and slow their eastward progression. And hence in areas where these troughs and ridges are climatologically favored, longer persistence of these more amplified features is bringing very significant effects. Drought in California and parts of the US Southwest, warming and reduced snowpacks in OR/WA/Southern BC, and colder, snowier, more turbulent winters in the eastern US and Canada.
This past winter has been particularly egregious in illustrating what is occurring, as you can see here.
And now, there can be no denying the fact that our having a CO2 level in the atmosphere of 400ppm (up from 280ppm 120 years ago, due to fossil fuel combustion) is warming the Earth. It has been physically proven, as the following research shows.
First direct observation of carbon dioxide's increasing greenhouse effect at Earth's surface
Date:
February 25, 2015
Source:
Lawrence Berkeley National Laboratory
Summary:
Scientists have observed an increase in carbon dioxide's greenhouse effect at Earth's surface for the first time. They measured atmospheric carbon dioxide's increasing capacity to absorb thermal radiation emitted from Earth's surface over an 11-year period at two locations in North America. They attributed this upward trend to rising carbon dioxide levels from fossil fuel emissions.
The basic physics behind CO2 and other greenhouse gasses (like Methane, CH3, which is 23 times more potent than CO2) causing atmospheric warming was first worked out over a century ago by Nobel-prize winning Swedish chemist, Svante Arrhenius.
The last several years of these erratic conditions in the Northern Hemisphere jet stream have been the subject of research, and now it looks as though the answers are coming in.
Weird Winter Weather Plot Thickens as Arctic Swiftly Warms
Scientists are working out potential linkages between rapid Arctic warming caused by climate change and a more wavy jet stream causing weird winter weather
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.
Credit: Stuart Rankin/Flickr
More In This Article
Editor's note: The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.
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.
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.)
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.
Slowing, drunken path
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.
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.
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.
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 of recent studies 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.
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.
So there you have it folks. Remember too, as research from around the Lake Elgygytgyn in northern Siberia has shown, the last time atmospheric CO2 levels were at the current 400ppm, 3 mya, average surface temperatures in the Arctic were 5-10C warmer than they are currently, and global sea levels were 20m higher (meaning most of Greenland was ice free, and significant parts of Antarctica). Humanity is on track to push atmospheric CO2 levels to at least 550ppm by 2060 through unrestrained fossil-fuel use and tropical rain-forest destruction, what kind of effects do you think that will bring?
BETWEEN EXTREMES
Here in the Central Rockies, we have been fairly fortunate this winter, our position between the "Ridiculously Resilient Ridge" along the West Coast, and deep eastern North America trough, has given us relatively tranquil weather and near average snowpacks, at least for most of Montana. The West Coast ridge has occasionally weakened/retreated west, and allowed cooler weather systems to bring actual winter weather even to the lower elevations.
Because although the past 90 days, generally speaking, have seen temperatures significantly above-average in this region, November saw much cooler conditions, and a good beginning to winter snowpack accumulation. The reason snowpacks are so incredibly low in Oregon/Washington (which is unprecedented!), is not because of a lack of precipitation there, but that their winter storms have been much warmer, bringing snow only to the very highest elevations, 2000-3000m. Whereas our weather systems this winter have often come into this region from the northwest, with lower snow levels, most of the time.
Thus, in the areas where we like to engage in our winter recreational activities such as nordic skiing, as here along the Bitterroot Divide near Lolo Pass at 1900m, there is a generous snowpack.
Or here, at 1600m on the east slopes of the Mission Mountains, on 22 Feb. In spite of our very warm late Jan. through about 20 Feb., during the past week, the strong ridging over the entire western US weakened over the Central Rockies, and allowed colder air and some light snow to return.
Just before this time though, most of the snow had melted around the higher points surrounding the Missoula Valley. Here on 15 Feb., on top of 1780m Univ. Peak, only patches were left on the NW-NE facing slopes. 
And the colder November that we experienced here when the West Coast ridge retreated some, as evidenced by these temperature anomalies, allowed the beautiful large waterfall 12km in up the Bass Creek canyon in the Bitterroot Mtns. to nearly completely freeze over.
Below you can see the full extent of these incredible falls that are about 15m tall and 40m across.
Our associate editor Mattie here provides a sense of scale to the falls as she investigates the ice.
It required some effort getting in here last 21 Nov., hiking in through 20-30cm deep snow, with patches of solid sheer overflow ice, at times. Having Katoolah micro-spikes proved essential, I would not have made it in here otherwise.
Not a great deal of new snow has fallen since the big late Jan.-20 Feb. warm-up, and not a great deal more is expected for the next week, just about 10cm with our next cold trough in a few days. So we'll give it a go next weekend, to see if we can make it in there and check how the ice loading has changed on these amazing falls.
We feel very fortunate to live in this beautiful region, with so many interesting natural areas available to us to recreate in. And which so far, has been relatively (but not completely) tranquil and enjoyable compared to other parts of North America. In a future article, we'll try and describe what we think the long-term effects of the jet stream slowing and major features amplification will bring to this region. Cheers.
