Friday, December 16, 2016

2513. An Unusually Warm Arctic Year: Sign of Future Climate Turmoil?

By Fen Montaigne, Environment 360, December 5, 2016
Jennifer Francis

Atmospheric scientist Jennifer Francis has for five years propounded a widely discussed theory about the rapidly warming Arctic and global weather: Rising temperatures in the Arctic, closely intertwined with the loss of sea ice, are changing the shape of the jet stream and altering the weather of the Northern Hemisphere. 

Some climate scientists and meteorologists have embraced her theory, while others have adopted a wait-and-see attitude.

But this year’s freakishly warm Arctic weather is lending credence to her hypothesis that a lessening of the temperature difference between the Arctic and the mid-latitudes is causing the jet stream to wobble, allowing warm air to flood into the north polar regions and sending frigid air southward into parts of Asia. More profound changes are in store as the Arctic continues to warm, says Francis, a research professor at Rutgers University. 

In an interview with Yale Environment 360, Francis discusses the perilous state of Arctic sea ice, explains why large portions of the Arctic have experienced temperatures more typical of New York City, and warns that we ignore the climate upheaval in the Arctic at our own peril. “The speed of the change is what is very disturbing to me,” says Francis, “because it's such an indicator of what's happening to the planet as a whole.” 

Yale Environment 360: What is happening in the Arctic this year, and how exceptional are the temperatures being recorded and the sluggishness of sea ice formation? 

Jennifer Francis: We've been watching the Arctic very closely for years, but this year it's been particularly interesting. It's not just the bizarre behavior that's going on right now, but really it started in the beginning of this year. It's been pretty much in record territory in terms of sea ice and high temperatures almost every month. Of course, this is continuing a trend that has been going on for a few decades now where we've been watching the sea ice decrease, mostly in the summer, but also in the other parts of the year. We see the Arctic warming much faster than elsewhere on the globe. It's really part of a bigger, longer story that has unfolded in a big way this year. 

e360: What are some of the exceptional temperature anomalies that you're witnessing? 

Francis: We've been seeing air temperatures that some days exceed 20 degrees Centigrade — 36 F — [above the long-term average] over the whole Arctic. We're not talking about one spot. This is a very broad area of warming. The maximum warming is pretty much focused in the region that we call the Barents and Kara Seas, which is the part of the Arctic that's just north of, say, Scandinavia and western Russia. This particular area seems to be a real hot spot. It's one of the places where the sea ice has been disappearing the fastest. That often seems to have a big impact on weather patterns in the region and well downstream into Asia.
What we're seeing happening now is completely different from what we would have seen if we looked down on the earth 30 years ago."

The other area that's been warming really quickly is over on the Pacific side of the Arctic, toward Alaska and far eastern Russia, a region called the Chukchi Sea and the Beaufort Sea. Some years we see the sea ice disappearing to a huge extent over there. The sea ice has grown this fall to pretty much cover that area now, although we know it's very thin. Over on the Barents-Kara side, we're still seeing a lot of open water. Very bizarre. 

e360: Forty or 50 years ago, of course, these areas would been covered with sea ice even in the summer, not to mention in the fall? 

Francis: Right. What we're seeing happening now is completely different from what we would have seen if we could have looked down on the earth even 30 years ago. We don't have to go back very far to see an Arctic that had a lot more ice in it. 

e360: So what we're seeing this year is not only no summer ice, but a really slow formation of ice in the fall as well? 

Francis: That's right. Those things are connected, obviously. When we lose a lot of ice during the summertime, it makes it harder for the ice to grow back. During the summer, if you have less ice, then the Arctic Ocean absorbs a lot more of the sun's energy. Come fall, when the ice is supposed to form again, that water is so warm that it first has to release all that extra energy it absorbed during the summer back to the atmosphere, which of course warms the air.        

It also releases a lot of water vapor into the air. That water vapor is a greenhouse gas, along with carbon dioxide and the other ones we know about. It acts to trap even more heat down at the surface. That extra water vapor plays another very important role, which is it tends to cause more clouds to form. Those clouds are also very good blankets on the system. We have all these self-reinforcing cycles happening up there when we lose a lot of sea ice. 

e360: What are the immediate causes of this exceptional year of warm weather in the Arctic and this particularly warm autumn?

Even a few degrees of extra temperature represents a huge amount of heat that can warm the atmosphere for a long time."

Francis: There are a number of factors that are involved here. One goes back to what I was describing earlier, where when we lose a lot of ice, it tends to hold that heat into the fall and delay the formation of the freeze-up time. Another reason this year is the tendency for the jet stream — and the jet stream is intricately connected to the Arctic in many ways — to take a very large swing north and south. When we get one of these big northward swings, like we had at the very beginning of 2016, it made a lot of headlines when it went above freezing at the North Pole. We've been seeing these northward swings over and over again this year, and particularly this fall. 

When we get those big northward swings, we tend to see a lot of extra heat and moisture from the lower latitudes transported up into the Arctic. The moisture is one of the big keys to this whole story. Ocean temperatures all around the Northern Hemisphere are running well above normal. When the jet stream is able to take one of these big northward swings, it's bringing even more heat and moisture northward than it would have, say, 30 years ago. That moisture adds to the extra water evaporating from the surface up there. We're seeing record amounts of water vapor in the Arctic this year. This is a really important part of the story. 

e360: What kind of sea surface temperature anomalies are being observed this fall up in the Arctic? 

Francis: They are certainly a few degrees [C] above normal, which doesn't sound like much, but water holds a lot of heat. Even a few degrees of extra temperature represents a huge amount of heat that, once it's released into the atmosphere, can warm the atmosphere for quite a long time. 

e360: Is what we're seeing this fall a taste of what is likely to come in terms of warmth in the Arctic, sea ice cover, et cetera? 

Francis: It's hard to say how this all could rebound after this very extreme fall. It is definitely consistent with the trend that we've been watching over the last 30 years or so. Perhaps it's signaling an acceleration of that trend. Again, we'll have to wait and see how it pans out. It could be that we're seeing some of this heat as a residual of the near record-breaking El Niño last winter, so the ocean is now releasing a lot of heat that El Niño was contributing to in the Pacific. Yet even without that El Niño, the oceans are running well above normal in terms of temperature. There's a lot more energy and heat in the global system that is amplified when it gets up to the Arctic through these self-reinforcing cycles that I was describing. 

I have no doubt whatsoever that human activities are the cause of this. Just in the specific issue of El Niños, we can look back over the record and see what the sea ice did during past bouts of El Niño. You see no indication in the sea ice record that El Niño had any impact, or very little impact, on what the sea ice did. We're in a situation now where the sea ice in the Arctic is so thin that it can respond much more quickly to any abnormalities that might happen in the climate system, including an El Niño.
Arctic sea ice extent as of November 1, 2016, as compared to previous years and the longer term 1981 to 2010 average.
e360: I’d like to ask you about your ideas on the impact of declining Arctic sea ice on the jet stream. 

Francis: It was only late in 2011 when I started to look into how the sea ice disappearing so rapidly within the Arctic might have an effect on the atmosphere, not just in the Arctic, but far away, all the way down to even Florida, for example. We've known for a long time that the difference in temperature between the Arctic and areas farther south — of course the Arctic being cold, and the mid-latitudes being much warmer —is really the fuel behind what drives the jet stream. 

The jet stream is literally a river of wind that flows where the jets fly. The jet stream is really the reason we have shifting weather patterns down here in mid-latitudes. Anything that affects the jet stream is going to affect weather patterns. What we're seeing, though, is that because the Arctic is warming so much faster than anywhere else, this difference in temperature between the north and the south is getting smaller. That, in turn, means that the jet stream is getting weak — this is something that we are able to measure. 

When the jet stream gets weaker, it tends to be more susceptible to any obstacles in its path. If it runs into a mountain range, for example, or an area of very warm temperatures over the ocean or over the land, and it's more easily deflected from its straight west-to-east flow around the Northern Hemisphere. We tend to see these bigger swings northward and southward when the Arctic is far warmer than it should be. The reason those big waves in the jet stream are important is because it's really the waves that create the weather patterns that we feel on the surface. Certain parts of the wave create high pressure and nice weather, and then other parts of the wave are responsible for storms. When the wave is big, they also tend to remain in one place for longer periods of time. It makes our weather patterns and our weather regimes hang around a lot longer.        

e360: This lessening of the temperature difference between the polar regions and the mid-latitudes, is that a key factor in the northward flow of warmer air into the Arctic? In essence, the jet stream is no longer the barrier it once was? 

Francis: Yes. This is an interesting new piece of the story that seems to be unfolding this year, particularly. The jet stream has been very wavy and there have been these big ridges — northward swings into the Arctic that have transported a lot of heat there. The warm Arctic probably had a role in making those bigger waves in the jet stream last winter and on into the summer, which perpetuated and intensified the warming of the Arctic, which then fed back to weakening this temperature difference and making the jet stream perhaps even wavier.

This year was not unexpected — it was a continuation in the losses of ice and the warming in the Arctic."

Again, it’s another one of these vicious cycles that involves the Arctic and the mid-latitudes through the jet stream. 

e360: When you begin to look at these feedbacks, it's very sobering how quickly they can build on one another. 

Francis: Yes, it's hard to get your head around it. I'm sure there will be more surprises coming our way. This year was not unexpected. It was a continuation in the losses of the ice and the warming in the Arctic. I would say it's certainly a bigger, stronger, and more alarming event than probably anybody was expecting to see this year. As we look into the future, are these kinds of spikes in temperature and sea ice loss going to continue? Are we going to perhaps see the sea ice disappear even faster than we expect? I hate to think it, but it's probably likely. Pretty much all of the changes that we expect to see happen in the climate system have been occurring more rapidly than we expected. 

e360: If the changes in the jet stream that you have been describing continue, what could the impacts be in the U.S., Europe, or Asia in terms of altered weather patterns and the effects on agriculture, et cetera? 

Francis: The bottom-line message is that we expect weather patterns to become more persistent. It's about particular weather patterns just being stuck in one place for a long time. With the Arctic being so warm, it is causing weather patterns to hang around a lot longer. 

This has a lot of implications for all sorts of things. In the case of weather patterns, most likely we'll see more prolonged droughts, not necessarily in one place over another. We might see more harm from flooding caused by heavy rain events that stay in one place for a long time. All of those very long-lived weather patterns tend to create conditions that are a real challenge to transportation and agriculture. 

e360: You mentioned that there's a disturbing aspect to these really profound changes happening in the Arctic. How do you feel watching this great white cap of ice that has been there for thousands of years steadily shrink? 

Francis: We weren't even talking about Arctic climate change very much when I was at graduate school in the early 1990s. It really evolved to become a thing since then, which is part of the disturbing part, how fast this has really changed. We literally lost half of the ice up there just in a few decades. The speed of the change is what is very disturbing to me because it's such an indicator of what's happening to the planet as a whole.

The top of the world is turning from white to blue in summer as the ice that has long covered the north polar seas melts away. This monumental change is triggering a cascade of effects that will amplify global warming and could destabilize the global climate system. 

It's like taking a magnifying glass and making the problem look much bigger, because the Arctic is much more sensitive to changes. 

I suppose more worrying is the fact that we're doing so little about it. It should be setting off warning bells all over the place because it's such an obvious result of increasing the greenhouse gases in the atmosphere. Yet, there's still a large fraction of our country, especially, where people don't think this is causing it.

If there's any silver lining to all this, my hope is that these really conspicuous, rapid changes are going to be noticed by more of the public and they're going to realize that the people who've been saying that this is not a big problem, that it's really not happening and that humans don't have anything to do with it, they're going to start to question that opinion and realize that they've been fed a pile of lies, basically, and that this is a really big problem that's going to affect all of us. 

Fen Montaigne, who conducted this interview, is senior editor at Yale Environment 360. 

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