The climate is changing: the Arctic Dipole emerges
The dramatic loss of Arctic sea ice in recent years has created a fundamental new change in the atmospheric circulation in the Northern Hemisphere that has sped up sea ice loss and is affecting fall and winter weather across most of the Northern Hemisphere, according to several recent studies. Arctic sea ice loss peaks in September and October, exposing a large area of open water that heats the air above it. This extra heat has helped drive September - November air temperatures in the Arctic to 1°C (1.8°F) or more above average over about half of the depth of the lower atmosphere (Figure 1). This deep layer of warm air has grown less dense and expanded, pushing the top of the troposphere (the lower atmosphere) higher. The result has been a decrease in the pressure gradient (the difference in pressure) between the North Pole and mid-latitudes. With not as much difference in pressure to try and equalize, the jet stream has slowed down in the Arctic, creating a major change in the atmospheric circulation for the Northern Hemisphere.
Figure 1. Cross section of Arctic temperature anomaly from 1000 mb (the surface) to 300 mb (roughly, the height of the top of the lower atmosphere or troposphere). Cross section is taken along the Date Line (180°W), from 60°N latitude (left side) to the North Pole (right side), for September - November for the 12-year period 1998 - 2009. Three year averages were done to reduce the amount of year-to-year noise associated with natural variation. Other cross sections along different lines of longitude show similar results, though typically with more warming aloft and less warming at the surface. Image credit: NOAA/ESRL.
A new atmospheric pattern emerges: the Arctic Dipole
In a 2008 article titled, Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system Zhang et al. show that the extreme loss of Arctic sea ice since 2001 has been accompanied by a radical shift of the Arctic atmospheric circulation patterns, into a new mode they call the Arctic Rapid change Pattern. The new atmospheric circulation pattern has also been recognized by other researchers, who refer to it as the Arctic Dipole (Richter-Menge et al., 2009). The old atmospheric patterns that controlled Arctic weather--the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO), which featured air flow that tended to circle the pole, now alternate with the new Arctic Dipole pattern. The Arctic Dipole pattern features anomalous high pressure on the North American side of the Arctic, and low pressure on the Eurasian side. This results in winds blowing more from south to north, increasing transport of heat into the central Arctic Ocean. The Arctic Dipole pattern occurred in all summer months of 2007 and helped support the record 2007 summer reduction in sea ice extent (Overland et al., 2008). Overland et al., 2010 also found that the Arctic Dipole pattern tended to create an increase in easterly winds in the lower half of the atmosphere of 40% in fall, between 2002 - 2008. Fall 2008 through spring 2009 featured the old AO pattern. The new Arctic Dipole pattern re-appeared in June - July 2009, but the old AO pattern dominated in August - September, resulting in greater sea ice extent than in 2007 and 2008. The Arctic Dipole pattern was active again in October, inactive in November, and reasserted itself this December. As a result, Arctic sea ice reached a new record minimum for a 10-day period in early November, increased above record lows during late November and early December, and appears poised again to reach a new record minimum later this December (Figure 2).
Figure 2. Sea ice extent in the Arctic for this year (blue line) compared to the record low year of 2007 (green line) and 1979 - 2000 average (gray line). One could make the ice loss looks less significant by using the full satellite data record from 1979 - 2008 for the average. Image credit: National Snow and Ice Data Center.
Arctic Dipole blamed for colder winters in East Asia
It turns out that the new Arctic circulation patterns help to intensify the Siberian High, a large semi-permanent region of surface high pressure prevalent in winter over Siberia. According to Honda et al. (2009), this results in increased flow of cold air out of the Arctic in early winter over eastern Russia, Japan, Korea, and eastern China, causing colder temperatures. By late winter, the pattern shifts, resulting in colder than average temperatures from East Asia to Europe.
Arctic Dipole blamed for drier winters in Northern Europe
Francis et al. (2009) found that during 1979 - 2006, years that had unusually low summertime Arctic sea had a 10 - 20% reduction in the temperature difference between the Equator and North Pole. This resulted in a weaker jet stream with slower winds that lasted a full six months, through fall and winter. The weaker jet caused a weaker Aleutian Low and Icelandic Low during the winter, resulting in a more negative North Atlantic Oscillation--a pattern that usually brings reduced winter precipitation over Alaska and Northern Europe and increased precipitation over Southern Europe. A more negative NAO also tends to bring cold winters to eastern North America and Europe. Though it was not mentioned in the article, reduced Arctic sea ice may also cause dry early winter conditions in the U.S. and the Caribbean (Figure 3). The authors noted that strong La Niña or El Niño events can have a much larger influence on the wintertime atmospheric circulation, which will overshadow the changes due to Arctic sea ice loss.
Figure 3. Difference in early winter precipitation (November - January) between five years that had low Arctic sea ice (2005, 2006, 2007, 2008, and 2009), and five years that had unusually high Arctic sea ice extent (1981, 1984, 1986, 1989, 1993). Note that low sea ice may be responsible for dry conditions in early winter for the Caribbean and most of the U.S.
Commentary
Arctic sea ice loss appears to have created a new atmospheric circulation pattern that brings more warm air in the Arctic, creating a positive feedback loop that causes even more sea ice loss. This feedback loop increases the likelihood that an ice-free Arctic in the summer will indeed come by 2030, as many Arctic experts are predicting. It's worth noting that such an atmospheric circulation shift was not predicted by the climate models. Indeed, the loss of Arctic sea ice over the past three years exceeds what any of our models were predicting (Figure 4). While we can rightly criticize these models for their inaccuracy, we should realize that they are just as capable of making errors not in our favor as they are of making errors in our favor.
Figure 4. Arctic sea ice extent from observations (thick orange line) and 13 model forecasts used to formulate the 2007 IPCC report (light lines). The thick black line is the multi-model ensemble mean, with the standard deviation plotted as a dashed black line. Image has been updated to include the observed 2008 and 2009 measurements. None of the models predicted the record 2007 sea ice loss. Image credit: Arctic sea ice decline: Faster than forecast by Stroeve et al., 2007.
References
Francis, J.A., W. Chan, D.J. Leathers, J.R. Miller, and D.E. Veron, 2009, "Winter Northern Hemisphere weather patterns remember summer Arctic sea-ice extent", Geophysical Research Letters, 36, L07503, doi:10.1029/2009GL037274.
Honda, M., J. Inoue, and S. Yamane, 2009. Influence of low Arctic sea - ice minima on anomalously cold Eurasian winters, Geophys. Res. Lett., 36, L08707, doi:10.1029/2008GL037079.
Overland, J. E., M. Wang, and S. Salo, 2008: The recent Arctic warm period, Tellus, 60A, 589.597.
Overland, J. E., and M. Wang, 2010: Large-scale atmospheric circulation changes associated with the recent loss of Arctic sea ice. Tellus, 62A, 1–9.
Richter-Menge, J., and J.E. Overland, Eds., 2009: Arctic Report Card 2009, http://www.arctic.noaa.gov/reportcard.
Simmonds, I., and K. Keay (2009), Extraordinary September Arctic sea ice reductions and their relationships with storm behavior over 1979.2008, Geophys. Res. Lett., 36, L19715, doi:10.1029/2009GL039810.
Wu, B., J. Wang, and J. E. Walsh, 2006: Dipole anomaly in the winter Arctic atmosphere and its association with sea ice motion. J. Climate, 19, 210-225.
Zhang, X., A. Sorteberg, J. Zhang, R. Gerdes, and J. C. Comiso (2008), Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system, Geophys. Res. Lett., 35, L22701, doi:10.1029/2008GL035607.
Jeff Masters
Reader Comments
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Errrr,...???
How is it possible to be 50% below sea level?
I always thought you were either at or above sea level and if you were below sea level, you were under water. I know all about dikes and barriers; but, the question remains as to how one is 50% below sea level.
Either you are or your aren't. Does that mean you are waist deep when you are 50% sea level?
Please explain.
by the way, i hope i didn't insinuate that you were spinning the data--i'm a very data-driven guy and i always prefer to see raw data over averages...and i usually prefer to see ALL of the raw data :) thanks for making the footnote, though...
Here is one for you. As you know millions of palms have died in Florida and the Caribbean since the 1970's. Never really found out why? Also, recently S. Florida had an invasion of white flies which killed most of our giant ficus trees and hedges, which as anyone who lives or visits here are widely used. They were devastated. Where did these invasive species come from?
sorry for any confusion, it's an old joke on the blog from awhile back :P
Thank you.
Never quoted myself before, but if you read the part that says "this entry is for the sole enjoyment of TD only" It is an old joke on the blog which many of us like to repeat for quiet, nice little moments like this. It is called levity. It was not intended as a serious comment, hence, the clarification.
I just think that sometimes we should all lighte up a bit. After all, if they climate is going to get warmer, we must learn to "cool down" It is often referred to as adaptability.
A great deal of them come from South America.
There is, currently, a beetle and its larva that is threatening to cause the extinction of the larger bromeliads here in the US and south of here as well. At this time it appears that only those large species are at risk because the larva is so large. Time to extinction? Approximately 20 years.
"A more negative NAO also tends to bring cold winters to eastern North America and Europe."
AO is so strongly negative right now it is off the chart.
In that case I'll take one from column A and 2 from column B. I always enjoy a little kidding, not enough of that sometimes.
It is currently still on the CPC AO charts. The ensembles don't show it going off the charts until next week.
That is what I meant. And my hurricane is stronger than yours! (:
My entire yard is surrounded by 9" ficus hedges. I'll upload a picture on my blog for you. Can't tell you how much it has cost to keep them maintained. We have them under control, but our neighborhood was devastated. Thanks for the info.
LOL j/k :)
Actually, VA they do work together all the time. They rely heavily on each other's research. Each segment of science relies on other fields to reinforce or dispel a theory. The theories or hypotheses concerning climate are always discussed with members of all the fields which you mentioned and many others. Very valid observation on your side and a point well worth making.
One problem, if you are 7 feet tall and the guy next door is 4 feet tall, how deep is the 50 % below sea level?
Can you please explain the use of the phrase "in our favor" here:
If you're looking for a specific species, you could check out http://www.invasivespecies.net/
Didn't know about the palms in Florida but, then again, I'm new to the area. Could blame it on the Love Bugs which come to find out, despite the myths is also an invasive species here. Just kidding about the Love Bugs by the way. I'd never even heard of them before I experienced them a couple months back. Sounds like there is some disease hitting certain variations of palms here.
You got us there!! LOL
Boy, trinigirl, you ask me to ask you questions about invasive species, then you give a link to look it up?? LOL
I mean, Greenland is called "Green-land" for a reason. It used to be much greener around the year 1000 AD...according to Viking history and archeology. What did the satellite date look like for the years + or - 20 years from the year 1000 AD? Oh, that's right...no satellites back then. This warming was ALL pre-Industrial Revolution.
If there is climate change, it is natural, not man-made. And remember, climate change might also mean that it changes BACK.
Interestingly enough is that newer research leads some to believe that a changing climate here in the States might actually be beneficial for the ecosystem when talking about currently invading species. Some of these 'weeds' might find they are no longer in such a hospitable environment and native species would be better suited to adapt and cope with the changes. Thus the harmful pests would die off, leading to a restoration of the landscape.
Of course, this is not an absolute but it is intriguing.
Hey, I pointed you in the right direction my friend :) I could give you my thoughts on the overall spreading of invasive species...the whys, whats wherefores and that sort of mush but unless you stick with the species I personally studied, I couldn't give you an answer post haste. I have never studied the white flies and am too new to the area to tell you much about the trees here...yet. My Masters works was in biogeography over on that other coast. Plenty o' weeds to keep me busy there.
Oh and just saw the Love Bug thing. I had a woman tell me they were engineered here. She didn't seem to appreciate it when I laughed. I thought she was joking but come to find out, it is a common urban legend. Why does it take somebody moving from another State to set these people straight?
Try raspberry ants.
"They feed on ladybugs, fire ants and Attwater's prairie chicken hatchlings, as well as plants. They are able to out-compete fire ants because they reproduce faster.[5] The ants are not attracted to ordinary ant baits, are not controlled by over-the-counter pesticides,[7] and are harder to fully exterminate because their colonies have multiple queens.[8]"
"In areas infested by the Rasberry crazy ant, large numbers of ants have accumulated in electrical equipment, causing short circuits and clogging switching mechanisms causing equipment failure."
I have heard that AC compressors, computers, and industrial equipment have been ruined.
http://urbanentomology.tamu.edu/ants/exotic_tx.cfm
bj, this question has been asked and answered many times in recent days. Being of Scandinavian descent and having lived a good part of my life in Europe, believe me, Greenland was not Green when my ancestors setteld there. There was a short period of time when the climate was slightly warmer and the southern coast allowed some grazing land and some trees. It lasted a very short time. At that time Greenland was covered with approximately 85% glacier. I have spent a lot of time there and recently got back from there one month ago. It they used the term "Greenland" to encourage people to go there and settle. In the same fashion, Iceland, which has a much milder climate was named that to discourage people from going there. Just google or whatever on the history of Greenland and you shall get a much clearer picture of the history. By the way, I visited the melting ice caps and glacial retreat. It is not a pretty sight. I would encourage others to go and see for themselves. It brings tears to one's eyes.
LOL :P
Some of those dates actually had a +AO with Dec 1983 and Dec 1989. Jan 1977 and Han 1985 were negative with Jan 1977 being the most negative. The projected AO looks more negative.
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