05 Mar 2012

Linking Weird Weather to Rapid Warming of the Arctic

The loss of Arctic summer sea ice and the rapid warming of the Far North are altering the jet stream over North America, Europe, and Russia. Scientists are now just beginning to understand how these profound shifts may be increasing the likelihood of more persistent and extreme weather.
By jennifer francis

Does it seem as though your weather has become increasingly “stuck” lately? Day after day of cold, rain, heat, or blue skies may not be a figment of your imagination. While various oceanic and atmospheric patterns such as El Niño, La Niña, and the North Atlantic Oscillation have been blamed for the spate of unusual weather recently, there’s now a new culprit in the wind: Arctic amplification. Directly related to sea-ice loss and earlier snowmelt in the Far North, it is affecting the jet stream around the Northern Hemisphere, with potentially far-reaching effects on the weather.

Arctic amplification describes the tendency for high Northern latitudes to experience enhanced warming or cooling relative to the rest of the Northern Hemisphere. This heightened sensitivity is linked to the presence of snow and sea ice, and the feedback loops that they trigger. For example, as sea ice retreats, sunshine that would have been reflected back to space by the bright ice is instead absorbed by the ocean, which heats up, melting even more ice. As the world has warmed since the fossil-fuel revolution after World War II, Arctic temperatures have increased at more than twice the global rate. A dramatic indicator of this warming is the loss of Arctic sea ice in summer, which has declined by 40 percent in just the past three decades. The area of lost ice is about 1.3 million square miles, or roughly 42 percent of the area of the Lower 48 United States.

Extra heat entering the vast expanses of open water that were once covered in ice is released back to the atmosphere in the fall. This has led to an increase in near-surface, autumn air temperatures of 2 to 5 degrees
All that extra heat being deposited into the atmosphere cannot help but affect the weather.
C (3.6 to 9 degrees F) over much of the Arctic Ocean during the past decade. All that extra heat being deposited into the atmosphere cannot help but affect the weather, both locally and on a large scale. And there are growing indications that some weather phenomena in recent years — such as prolonged cold spells in Europe, heavy snows in the northeastern U.S. and Alaska, and heat waves in Russia — may be related to Arctic amplification.

But if so, how does it work?

The Arctic region is of course colder than the temperate zones, and it is this difference in temperature that propels the west-to-east river of fast-moving air known as the jet stream. This atmospheric feature separates warm air to its south from cold air to the north, and tends to follow a wavy path as it flows around the Northern Hemisphere between about 30 degrees N and 60 degrees N. It usually resides near the altitude where jets fly, hence its name. As high latitudes warm more than mid-latitudes, however, this north-south temperature difference weakens, which has two impacts on the jet stream.

The first effect is to slow the west-to-east speed of the jet stream, a phenomenon that already appears to be occurring. Upper-level winds around the Northern Hemisphere have slowed during autumn, from October to December, which is exactly when sea ice loss exerts its

View gallery
Minimum summer sea ice Arctic 1979 2011

The Cryosphere Today/Polar Research Group, the University of Illinois at Urbana-Champaign
Minimum summer sea ice in the Arctic Ocean, 1979 to 2011
strongest effect on the north-south temperature gradient. Some regions exhibit even larger drops in wind speed, such as over North America and the North Atlantic, where winds have slowed by about 14 percent since 1980. Theory tells us that a decrease in the west-east flow tends to slow the eastward progression of waves in the jet stream. Because these waves control the formation and movement of storms, slower wave progression means that weather conditions will be more persistent. In other words, they will seem more “stuck.” This effect appears to play an important role mainly in autumn, because as sea ice reforms in winter, the north-south temperature difference gradually returns to more normal values.

The second way that Arctic amplification is expected to influence the jet stream and our weather is by increasing the “waviness” of the jet stream. Because of Arctic amplification, the northern peaks of waves, called ridges, will experience more warming than the southward dips, called troughs. This is expected to cause the ridges to stretch northward, which will increase the size of the waves. Larger swings in the jet stream allow frigid air from the Arctic to plunge farther south, as well as warm, moist tropical air to penetrate northward. These wavy flows often lead to record-breaking temperatures. Meteorologists have also known for a long time that larger jet-stream waves progress eastward more slowly, as will the weather systems associated with them. Consequently this represents another mechanism that will cause weather conditions to linger.

Increased waviness seems to be occurring during summer, as well; but instead of sea ice loss, the culprit appears to be the progressively earlier melt of snow on Arctic and sub-Arctic land in the spring. As snow disappears, bare soil is exposed to the strong spring sunshine earlier, which allows it to dry and warm sooner. This effect is at least partly responsible for the approximately 2 degrees C of warming over high-latitude land areas since the mid-1980s. This heat contributes to Arctic amplification during summer, which is expected once again to stretch ridges northward, increase waviness, and promote sluggish weather.

There have been many examples of “stuck” weather patterns during the past few years. Deep troughs in the jet stream hung over the U.S. east coast and Western Europe during the winters of 2009/2010 and 2010/2011, bringing a seemingly endless string of snow storms and teeth-chattering cold. In the early winter of 2011/2012, in contrast, these
It’s increasingly likely that the weather you have today will stick around awhile.
same areas were under ridges, or northward bulges of the jet stream, which brought unusually warm and snowless conditions over much of North America. At the same time, however, a deep trough sat over Alaska, dumping record snows. In early February this year, the jet stream plunged unusually far southward over Europe, bringing frigid Arctic air and snow to some areas that hadn’t seen those conditions in over half a century. During summer, persistent weather patterns are responsible for droughts and heat. The record heat waves in Europe and Russia in the past several years have been linked to early snowmelt in Siberia, and a sluggish high-pressure area caused last summer’s sweltering conditions in the south-central U.S.

While it’s difficult to point the finger at Arctic amplification in causing any of these weather events, they are the types of phenomena that are expected to occur more frequently as the world continues to warm and the Arctic continues to lose its ice. Further research may find ways to predict which regions will experience which conditions. But in the meantime, it’s increasingly likely that the weather you have today will stick around awhile.


Jennifer Francis is a research professor at the Institute of Marine and Coastal Sciences at Rutgers University, where she studies Arctic climate change and the link between Arctic and global climates. She has authored more than 40 peer-reviewed publications on these topics. She was also the co-founder of the Rutgers Climate and Environmental Change Initiative.

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Bravo, bravo! Outstanding article!

Posted by Stan Scharf on 06 Mar 2012

So that explains the heat waves and winter freezes, lasting days and weeks, of my youth. . . 50 years ago. Yesterday it went down to -19. . . today it's heading for plus 12. This article is bunk.

Posted by Bram Moerman on 07 Mar 2012

Dr. Francis, I saw you speak about this at AGU this past December and was really happy to see this article written at a level that I can share with both my synoptic meteorology AND intro to climate change students. Thanks!

Posted by Keah Schuenemann on 07 Mar 2012

Great article. I'm sure the science will solidify on the causes and effects as we see continued heating, loss of Arctic sea ice, and earlier snowmelt on land. p.s. I wonder where Bram Moerman lives?

Posted by meltyman on 07 Mar 2012


Your article was referenced over at Judith Currys blog and I made two responses as follows (the article I refer to was a temperature reconstruction of CET from 1538 to 1659)

"The report says

‘Does it seem as though your weather has become increasingly “stuck” lately? Day after day of cold, rain, heat, or blue skies may not be a figment of your imagination. ‘

Interesting, because several months ago I very nearly suggested an article to you based on this topic, as looking at tens of thousands of testimonials of the weather (for my article ‘the Long Slow Thaw?') through the LIA (Hot and cold periods!) I was continually struck by the fact that weather patterns appeared to have become stuck and -in the case of the UK-a week of cold weather turned into 4 or 6 weeks and fundamentally affected the temperature record..

I have come increasingly come to believe (a putative theory?) that we need look no further than the weather becoming ‘stuck’ to explain such events as the LIA (not continually cold) or the MWP (not continually warm)

We don’t need to look at orbits or any other explanations but that the Jet stream seems to have become fastened in one position or other and then if you add in all the other sub factors such as EL Ninos etc etc our weather will assume the character of the resultant patterns-lots of easterlies for cold, lots of westerlies for warmth (in the UK)

The ‘weather became stuck’ theory is well worth investigating further as it seems more plausible to me than many other theories, but stickiness is not reserved for the modern era..

tonyb | March 8, 2012 at 11:54 am | Reply

Judith my 11.46

I note that I actually refer to this stickiness in the notes within the supplementary information to 'The Long slow thaw?’ as follows

“13) Due to its geographical location British weather is often quite mobile and periods of hot, cold, dry or wet weather tend to be relatively short lived. If such events are longer lasting than normal, or interrupted and resumed, that can easily shape the character of a month or a season. Reading the numerous references there is clear evidence of ‘blocking patterns,’ perhaps as the jet stream shifts, or a high pressure takes up residence, feeding in winds from a certain direction which generally shape British weather.”

So the stickiness observation you refer to has its precedents.

Posted by Tony Brown on 08 Mar 2012

So, does the INCREASE in Antarctic ice account for the current deep trough weather event that has brought heavy rains down from tropical north to flood large areas of the Australian east coast? As well as the massive Queensland flooding over the last two summers? Down here in Australia we have all been blaming the southern oscillation index, and of course, Tim Flannery, our official climate commissioner, who had been telling us in no uncertain terms that global warming meant that our dams would all be dry and that Perth would be the first modern city to be abandoned due to the big dry! Funny how the weather always changes, shame about the political climate.

Posted by ian hilliar on 08 Mar 2012

Referring to Ian Hilliar's comment:

A) The "increasing Antarctic ice" is a furphy, several areas of Antarctica have experienced ice increase, however this is easily explained as these areas are the 'pointy northerly extending bits' of the continent that are catching the southerly extending warmer and moister air. Not too difficult to see the correlation of more atmospheric moisture leading to greater ice formation on the westerly facing slopes that catch the roaring 40's.

B) Big floods? Really? You think this is unusual? Read some Dorothea McKellar for pity's sake. One of the countries most revered poets wrote about "droughts and flooding rains" as the norm for the country. This is just weather, this is not climate. Imagine how mobile our weather could become if we started experiencing the northern hemispheres atmospheric changes..... Three days of rain in NSW central west caused this current flood (Lachlan and Murrumbidgee rivers etc). Imagine if our weather became "stuck" and we got a week, or two weeks of that weather as a result of the changed climate.... that could set some new flood records (and flush out the murray river).

C) Just to make it clear - you are talking about current weather events, Tim Flannery is discussing the potential of long term climate trends.

D) To the actual climatologists/meterorolgists/ scientific statisticians...sorry for some of the generalisations in my rant!

Jennifer - thanks for the article and i (like many others) will watch the climate stats and the growing knowledge base to clarify the extent of this climate influence in the range of changes and influences that are becoming evident.

Posted by Matt Anscomb on 08 Mar 2012

This is the best explanation I've seen of phenomenon that I've noticed for the past several years. The onshore flow in the Gulf of Maine and Maritime Canada in recent springs has been increasing, and this can be attributed to the weakening of the jet stream extreme dips and dives of the jet stream have been very noticeable in the last 10 years: arctic air masses are like bubbles that are getting "pinched" causing them to become elongated and wobbly.

In fact, the recent heat wave in March saw the extreme southern jet stream dip over the western U.S., and this dip became cut off at one point over Canada. The mechanism Jennifer Francis outlines makes a lot of sense. I would like to see more data on the heating of the ridges and cooling of the troughs and how these interact with different air masses.

Posted by Ross Geredien on 26 Mar 2012

I believe the warming of our climate began with the invention of the internal combustion engine and
it's involvement with world events. It has been central to all of our wars and the civilian factory production of war materials. Likewise the growth of our cities. The use of internal combustion engines grew as the world population and cities, and inventions for uses for engines grew. It just took forty years or so to wear through the climate buffer before it became noticeable.

Then it was seventy years before and any real pollution control efforts began to take effect.

Posted by Tom Cowart on 12 Apr 2012

The current situation is definitely a complex matter. The sun is one powerful creation and the energy it produces is impressive. With the increasing greenhouse gases, I feel that if action is not taken there will be great consequences. The earth's population is increasing on a daily basis, also is the number of greenhouse gases. More gases in the air allow for more radiation to occurs which in turn leads to an increase in temperature. I honestly see this process continuing on until the ozone layer will no longer be of use. Seeing how the earth is such an industrialized place that requires astounding amounts of fuels to operate, a global safe solution does not seem to likely at the time. Although this is what really needs to take place.

I am a resident of Oklahoma and the weather here has definitely been "stuck". A year ago we were hit with a blizzard and this winter only trace amounts of snow were seen. The summers are getting warmer faster and are staying warmer longer. The future of this matter can be intimidating to gaze upon.

Posted by Jadkins on 19 Apr 2012

Seems plausible, but why do your Northern Hemi Snow Extent Graphs (Rutgers) show increasing trend lines for winter and fall but sharp decrease for Spring? It seems the data record is extrapolating long term trends over geologically insignificant time frames. 30-100 years isn't enough to make a claim.

Posted by DaveR on 21 May 2012

Dr. Francis,

I concur with Keah Schuenemann on 07 Mar 2012. I will use and discuss this article next fall with my high school students. Thank you for your clarity.

Posted by Jackie Kane on 29 May 2012

Great article Dr. Francis. Look forward to discuss with you at the end of the month :-)

Posted by Sander Geelen on 10 Jun 2012

In the United Kingdom we have 'lost' our summers. Normally the jetstream travels north of the UK in summer, drawing warm air from the south, giving us warm summers. Since 2006 the jetstream sits on or south of the UK. We now have cool, even cold summers with endless cold rain and winter storms. Its like endless November. We are likely to lose many of our butterfly species this year! Bees are decreasing in numbers and floods kill somebody somewhere every few weeks. Summer temperatures are increasingly below average. To conclude, the jetstream does appear to be getting 'stuck' in a pattern with an enormous loop dipping south over the Atlantic and excluding northwestern Europe from summer conditions year after year.

Posted by Mark Joseph on 01 Jul 2012

Dr. Francis,

Cliff Mass, University of Washington professor of atmospheric science, has recently criticized
James Hanson’s recent article in PNAS using probability arguments to attribute the increasing
frequency of extreme heat events to anthropogenic induced climate change.

In his criticism of Hansen, Mass notes that Hansen provides no physical process to link
increased greenhouse gases to extreme heat events. Mass referring to the Texas heat wave of
2011, states that:

“Something other than global warming produced the lion's share of the heat wave...and we know what it was: a major change in the circulation over the U.S. last summer.. . . And there is no reason to think, based on theoretical or observational research that this is anything but
natural variability. “

The emphasis is his. A commenter asked if your paper, Francis, Vavrus 2012, didn’t address a
potential mechanism. Cliff did not respond to this commenter but when I pressed him on it in an e-mail he stated

“Francis and Varvus has a major flaw....they only considered lower and middle tropospheric flow. The jet stream above is not weakening and thus their underlying mechanism does not make sense.”

Your complete paper is pay walled so I don’t have access to it. Mass’ dismissal of your work does not seem to be consistent with your very coherent blog post above. Your thoughts on this would be very important to me.

Posted by Paul Middents on 19 Aug 2012

Thank-you all for your interest in this work as well as your comments and questions -- which I only just discovered have been posted here!

In response to the previous post by Paul Middents and comments therein by Cliff Mass, I can only say that Cliff must not have read our paper carefully enough. First, we document a weakening of the 500 hPa flow (about 200 hPa below the typical jet stream altitude) in the ZONAL direction only, which is the component influenced by a weakening of the poleward thickness (or temperature) gradient. Others have documented this tendency, as well (see Liu et al, PNAS, 2012, for example). The jet stream overall is likely not weakening, and in fact, may be strengthening in certain locations and seasons owing to increased temperature differences between continents and warmer oceans in winter. The other feature we document is a northward shift in the peaks of ridges (northernmost extensions of waves) in the 500 hPa flow, which follow closely the path of the jet stream. This northward elongation increases the north-to-south amplitude of the waves, which is well known to slow the eastward progression of those waves, and thus the weather systems associated with them. These important details are what Dr. Mass seems to have overlooked.

In light of this week's astounding new record minimum sea ice extent, at least 2 weeks before the end of the melt season, I would like to emphasize that I don't believe there is a direct link between ice loss and summer heat waves and droughts, except that both are ultimately driven by increasing greenhouse gases. Our research suggests, however, that the robust trend in earlier spring snowmelt on high-latitude land (leading to earlier drying and warming of the soil, again reducing the poleward temperature gradient) may play an important role in the increasing frequency and severity of summer droughts and heat waves. Natural variability and global warming are also likely factors, and further research will elucidate the relative importance of each.

Finally, I'd like to respond to a comment by DaveR on May 12th, who asks how snowcover trends can increase in fall and winter but decline in spring. As sea ice continues to retreat, the additional open water allows greater evaporation during fall, which has been shown to enhance snowfall on nearby land areas (e.g., Ghatak et al, JGR, 2012). Increased warming in spring, however, melts that snow more rapidly than in previous decades, leading to the robust negative trends in snow cover over the northern hemipshere during April through July. Note that June and July 2012 set new records for the least amount of snow since measurements began in the late 1960s. DaveR also comments that this 45-year data record is too short to matter, but given the preponderance of corroborating observations and physical understanding available to us, it's becoming increasingly difficult to attribute these events to natural variability. In fact, I would argue that it's now impossible.

Posted by Jennifer Francis on 29 Aug 2012

Cliff Mass is arguing that adding a "little" bit of global warming to normal variability, there won't be bad effects. But adding temperature to a normal distribution of temperatures multiplies the probabilities of extreme events. The widening of the distribution that Hansen shows from observation further multiplies the probability of Bad Things Happening. I think that Mass knows the difference between adding and multiplying his accusation that Hansen is being "deceptive" is a clear case of the pot calling what he believes to be a kettle black.

Posted by Brian Dodge on 30 Aug 2012

The permafrost release will be the final nail in the coffin. Runaway heating is all but certain. Hug your kids.

Posted by eric smith on 31 Aug 2012

Outstanding article! I have been witnessing exactly what you're talking about for quite some time here in northern California. Wild swings in weather and getting stuck in a very slow moving pattern. Long lasting heat waves in the summer and unusually cold and dry patterns which hang around forever in the winter. This has been more and more pronounced for at the last few years. The world has never before seen so many humans burning so much fossil fuel. When is it going to end? I know what the answer is, and it aint going to be a pretty one!

Posted by Dano on 11 Jan 2013

I would just like to ask why you do not address the issue of government weather modification programs. Does this not have some added affect as to what you are saying about the ice cap melting. I live in Prescott, Arizona and I see the jets almost everyday now for about 3 years. It's obvious that they leave substances behind that then become weather formations or addition to an existing one. With documented proof as to the high concentrations of heavy metal ions such as strontium, barium, and aluminum. Please address this.

Posted by Cheyne on 15 Jan 2013

I,ve been fishing lobster off the west coast of Wales UK.for over 30 years the last five summers have been progressively wetter and windier. We hardly ever see Northerly winds any more.The climate is changing here day by day hour by hour.
What one earth does our government need to make it wake up. "Big Ben floating down the Thames maybe".

Posted by lobsterman on 06 Feb 2013



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