Dr. Ricky Rood's Climate Change Blog

Are the changes in the Arctic messing with our weather? Analysis

By: RickyRood, 9:20 PM GMT on January 26, 2014

Are the changes in the Arctic messing with our weather? Analysis

In the last blog, I promised an analysis of why I conclude that what is happening in the Arctic makes it to my list of the big-ticket items of the past year.

I want to start with the work of Jennifer Francis and her collaborators. Professor Francis gave an excellent seminar in my department last week, which can be viewed here. This seminar uses as a foundation the paper Francis and Vavrus (2012), Evidence linking Arctic amplification to extreme weather in mid-latitudes. There is a whole set of coherent and convergent evidence that documents the changes in the Arctic. There is an increase in temperature, which is much greater in the Arctic than at lower latitudes and in the tropics (Polar or Arctic amplification). This has led to large changes in Arctic sea ice and springtime snow cover. There has been a lengthening of the growing season and an increase in activity in the northern forests – the greening of the Arctic (200 blogs ago, Getting Ready for Spring 5).

In the past, roughly, 15 years, there has been an observed change in the of the Arctic sea-level atmospheric pressure (see previous blog). The pressure is slightly higher, which leads to a weakening of the stream of air that flows around the North Pole. I wrote a tutorial about this in Wobbles in the Barrier. Also in the past decade there have been a number of researchers, for example, Liu et al. (2012) who in Impact of declining Arctic sea ice on winter snowfall – noted circulation patterns that have “ … some resemblance to the negative phase of the winter Arctic oscillation. However, the atmospheric circulation change linked to the reduction of sea ice shows much broader meridional meanders in midlatitudes and clearly different interannual variability than the classical Arctic oscillation.”

These papers lead to a few questions. Are the changes in the Arctic sea-level pressure a direct consequence of local changes in the Arctic, or are they more closely related to changes in global circulation patterns? Are changes in the Arctic sea-level pressure causing changes in weather in the middle latitudes? Are the differences we have seen in the past 15 years indicative of a climate-change related differences in weather patterns? Is what we have traditionally called the Arctic Oscillation changing?

Trenberth and Fasullo are following the heat of the warming earth, with the primary goal of understanding of how much heat is contributing to warming the Earth’s surface air temperature versus how much is going to heating the ocean and melting ice and snow. Their focus is on approximately the past 15 years. Therefore, they pay attention to known ways that the atmosphere and ocean vary (Some previous tutorials: Still Following the Heat and Ocean, Atmosphere, Ice and Land). Trenberth and Fasullo document the strong influence of the 1997-1998 El Nino. El Nino typically has a large effect on global temperature. The 1997-1998 El Nino was especially large. Trenberth and Fasullo show that the temperature in the atmosphere and oceans still remembers the 1997-1998 El Nino. They also examine the Pacific Decadal Oscillation, which is characterized by sea surface temperature differences being above (or below) average in the north-central Pacific while they are below (or above) in the north and east Pacific near the Aleutian Islands and the Gulf of Alaska. The Pacific Decadal Oscillation has been in a pattern of being cooler than average in the north and east Pacific since the 1997-1998 El Nino. Trenberth and Fasullo document a pattern that spans the globe, and the changes in the Arctic are part of that pattern. Conversely, their analysis would suggest that the global aspects of circulation pattern are too large to be caused by changes in the Arctic – it just takes too much energy.

What might be a scientifically based difference between whether changes in the Arctic are part of a global pattern or caused by the loss of sea ice changing the absorption and reflection of solar energy is to some extent not relevant to the question about weather patterns over the U.S. My experience in scientific controversies of this nature is that there are usually both global and local pieces to the puzzle. Further, changes in the U.S. weather could be directly linked to changes in the Arctic as well as to global patterns. In both the Trenberth and Fasullo and the Francis and Vavrus (2012) analysis there are consequential changes in jet stream pattern which is strongly influential to weather in the U.S. and, in fact, all of the middle latitudes of the Northern Hemisphere.

It’s not surprising that changes in the polar jet stream, the river of air that meanders around the North Pole, would have a profound effect on weather in the U.S. The waves that make up the weather systems of winter storms, for example, draw their energy from the environment that forms the jet stream. The jet stream steers these storms. In classes on dynamical meteorology, students learn that what is going on at the jet stream is often better information for forecasting weather than what is going on at the surface. Though there is a direct link between the jet stream and weather systems, the path of cause and effect in the changes in the Arctic, changes in the jet stream and changes to extreme events in the U.S. is not easy to map.

We have seen observations from Francis and Vavrus and Liu et al. (2012) that suggest large meanders in the jet stream. Both of these papers suggest that the scale of these meanders is unprecedented and does not fit easily into the framework we have used historically to describe the Arctic Oscillation - the primary way we describe correlated variability between the Arctic and the middle latitudes. In addition to the Arctic Oscillation, another characteristic we use to describe mid-latitude weather is blocking. Blocking describes a pattern of atmospheric flow, perhaps a particular configuration of the jet stream. Blocking slows or stops the normal west-to-east movement of storms around the Earth. Here is a nice description of blocking. Blocking is most common with high pressure, and high pressure is associated with the northern meanders of the jet stream. Note, blocking is associated with the meanders in the jet stream, but large meanders do not always mean that our definition of “block” is fulfilled. Blocking patterns are difficult to predict on a case-by-case basis. Blocking patterns are known to be associated with droughts, floods, heat waves and cold snaps. Therefore, when we look to a way that changes in the jet stream might change the weather over the U.S. we logically look a changes in blocking, which will discussed more fully in next blog.

r

Cold Weather in Denver: Climate Change and Arctic Oscillation (8)

Climate Change and the Arctic Oscillation 2

Climate Change and the Arctic Oscillation 1

Wobbles in the Barriers

Barriers in the Atmosphere

Behavior

Definitions and Some Background

August Arctic Oscillation presentation

CPC Climate Glossary “The Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle latitudes fluctuates between negative and positive phases.”





Arctic Climate Change

Updated: 5:07 PM GMT on February 21, 2014

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Are the changes in the Arctic messing with our weather? Background

By: RickyRood, 4:02 AM GMT on January 14, 2014

Are the changes in the Arctic messing with our weather? Background

(20140115: Revision: This is a revision. In the comments on the original post rlk and ScottLincoln questioned the magnitude of the pressure change in the figure used in the paper. I wrote Kevin Trenberth, the author, and he confirms that the units should be pascals, not hectopascals. I thank rlk and ScottLincoln, and indeed, I should have flagged this as well, rather than noting how large it was and moving along in the original post. The conclusions in the blog are not altered.)

This entry continues with my listing of the big-ticket items in climate change since I last taught in April 2012. In the last entry I wrote about how the technology used to extract oil and natural gas, hydraulic fracturing (fracking), stood as a threat to climate change because it assured the availability of fuels that we preferred and, also, provided desirable jobs. Some would argue that fracking might diminish our use of coal, which is a good thing. This is likely true, but there are several issues that need to be analyzed in that conclusion: selling our coal to other countries, the complete accounting of greenhouse gases associated with fracking, the broader environmental consequences of fracking, the fact that there are no real disincentives for using fossil fuels, and the fact that all burnt fossil fuels have a long-term cumulative effect (My Michigan colleagues integrated assessment of fracking). I don’t want to diminish the importance that the carbon dioxide emissions in the U.S. have, perhaps, been decreasing in recent years; however, it is not a fact that suggests we are on a path to addressing the problems of climate change. I assert we remain in a situation where economic growth, which we require for well-being, is still strongly linked to energy use and carbon emissions. If our economy grows so will our emissions as the preliminary 2013 emissions suggest.

The second big-ticket item that I want to highlight is the work investigating the changes in the Arctic and the possibility that these changes are already influencing the weather in the continental U.S. and, more broadly, in the Northern Hemisphere. I have written about this extensively in my series on the Arctic Oscillation and the hot and cold fluctuations in the U.S. (link to last in series, also see links below). I take some pleasure in noting that back in December I wrote, “The whole Arctic air mass is starting to move east, which means it will get a lot more press.” I did not imagine that it would lead to all of the anxiety about the rogue polar vortex (We the geeks).

I will leave the machinations of polar-vortex mania to my more able colleagues. I want to analyze why this work about the Arctic Oscillation, the polar vortex and wild fluctuations between warm and cold weather is important enough to be on my list of big-ticket items.

There is little controversy that there have been massive changes in the climate of the Arctic. These are most easily noted in the large changes in Arctic sea ice. There is also a whole set of coherent and convergent evidence that documents the changes in the Arctic. The most direct evidence is the increase in temperature, which is much greater in the Arctic than at lower latitudes and in the tropics (Polar or Arctic amplification). Coincident with this warming is a lengthening of the growing season and an increase in activity in the northern forests – the greening of the Arctic (200 blogs ago, Getting Ready for Spring 5). There is controversy about whether these changes in the Arctic are causing changes to the weather at lower latitudes. There is also controversy about if there is a change in the weather at lower latitudes, is it due to the local changes in the Arctic such as loss of sea ice.

I want to start the discussion with Figure 11 from a paper by Kevin Trenberth and John Fasullo entitled, An apparent hiatus in global warming? I will write more about this paper in a future blog. Trenberth and Fasullo provide a self-consistent global analysis that tracks the heating of the planet. Figure 11 of this paper shows the difference in average sea-level pressure between two time periods. An average is taken for 1999-2012 and another for 1979-1998. The difference between the two averages shows an increase in sea-level pressure. This increase is represented by the large red area stretching from the North Atlantic, east of Greenland, to the Arctic Ocean and centered over the North Pole. The maximum magnitude of this increase is about 150 Pa (pascal). To put this in perspective the surface pressure of the Earth is often cited as being 1000 hPa (hectopascal).



Figure 1: Mean annual sea-level pressure differences from ERA-Interim Reanalysis for 1999–2012 and 1979–1998 in Pa (pascal, colors) and for surface wind vectors (arrows) in meter per seconds with the key at top right. (a) Map projection centered on the Pacific and (b) polar stereographic projection of the Northern Hemisphere. (Note the magnitude of pressure is in Pa, not hPa, which is a typo in the original manuscript.)(Figure 11 from An apparent hiatus in global warming?)

This increase in the Arctic sea-level pressure can also be viewed in terms of the strength of the polar vortex, or in terms of wind, the strength of the rotation of the wind. Low pressure is associated with a strong vortex with strong rotation; high pressure is associated with a weak vortex with less rotation (earlier blog on strong and weak vortex). Hence, the observations show that there is a weaker polar vortex. As measured in terms of the Arctic Oscillation, the Arctic Oscillation is more negative. From our narrow U.S. perspective, this is associated with cold and snowy conditions over the eastern half of the U.S. leading to exaggerated political and press attention and excess purchase of toilet paper and bread in supermarkets from Atlanta northwards. It is quite easy to conclude that for the past decade and a half the Arctic Oscillation has been more prominently in its negative phase.

The analysis of Trenberth and Fasullo comes to the conclusion that this change in the Arctic is the consequence of changes in the global distribution of mass of the atmosphere. Specifically, Trenberth and Fasullo trace the changes in the Arctic back to changes in the tropics. Placing the Arctic changes as a part of a global circulation change stands in tension to the conclusions of Jennifer Francis and her collaborators, who are quoted extensively in my blogs. Francis and Vavrus (2012) in Evidence linking Arctic amplification to extreme weather in mid-latitudes correlate the changes in sea-level pressure to changes in the sea ice, the Arctic Oscillation and snow cover. This is a focus on a direct local effect in the Arctic causing changes in the global circulation.

The work that I cite above, in all cases, points to a time in the past 15 years where the Arctic Oscillation is often in its negative phase. There is a difference between the researchers in the determination of cause and effect. The difference in cause and effect leads, perhaps, to different conclusions about the future. The question: in the future will the Arctic Oscillation be more prone to its negative phase? With that question, I introduce another paper, by Elizabeth Barnes and co-authors Revisiting the evidence linking Arctic amplification to extreme weather in midlatitudes. Barnes et al. analyze the simulations used in the most recent Climate Model Intercomparison Project (CMIP-5) and conclude that the models do not support the conclusion that the Arctic Oscillation will become more negative in the future.

In the next blog, I will discuss the arguments offered by these different researchers. Then I will provide my analysis of why I conclude that what is happening in the Arctic makes it to my list of the big-ticket items of the past year.

r


Cold Weather in Denver: Climate Change and Arctic Oscillation (8)

Climate Change and the Arctic Oscillation 2

Climate Change and the Arctic Oscillation 1

Wobbles in the Barriers

Barriers in the Atmosphere

Behavior

Definitions and Some Background

August Arctic Oscillation presentation

CPC Climate Glossary “The Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle latitudes fluctuates between negative and positive phases.”

Climate Change Arctic Sea Ice

Updated: 4:56 PM GMT on January 17, 2014

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We like to burn things

By: RickyRood, 5:59 AM GMT on January 06, 2014

We like to burn things

In preparation for teaching this term, I have been thinking of the big ticket items in climate change since I last taught in April 2012. I will start with a very old quotation. I am reading The Travels of Marco Polo. Book II describes the Court of Kublai Khan and there is a chapter “Concerning the Black Stone Dug in Cathay Used for Fuel.” It starts

“Throughout this province there is found a sort of black stone, which they dig out of the mountains, where it runs in veins. When lighted it burns like charcoal and retains the fire much better than wood …”

This was written in about 1300.

Last year I wrote a blog All the Oil we Want.

In the middle of November 2012, there were many press stories that talked about the growing production of oil and natural gas in the United States (for example). The news stores followed a press release from the International Energy Agency (press release: North America leads shift in global energy balance, IEA says in latest World Energy Outlook).

This press release was for the World Energy Outlook 2012 (Executive Summary). The gist of the report is that there have been fundamental changes in the production of oil and natural gas in the United States. The changes have come from the successes of unconventional methods of releasing oil and gas from reservoirs that were previously felt to be too costly to exploit. One of the core technologies used to release these stores of fossil energy is hydraulic fracturing or fracking. This report goes on to say that the U.S. will out produce Saudi Arabia in the mid-2020s and that the U.S. is on its way to being energy independent by 2035.

I had several fast reactions to this report. My first was imagining the geopolitical landscape if the U.S. did not have deep energy roots in the Middle East, and indeed, in all parts of the world. Then I imagined other countries expressing their energy-related interests throughout the world. I also felt that this prediction will have profound effects on how we think about climate, climate change and ultimately, on the Earth’s climate.

Beyond the happy headline of U.S. energy fortunes, the report talks about the rapidly growing energy demands in China, India and the Middle East. It then discusses that we are “failing to put the global energy system onto a more sustainable path.” Much, nearly half, of the world’s growth in energy consumption in the past decade has used coal. Looking forward, coal remains central to energy use in China and India. Coal has many negative environmental consequences, including high carbon dioxide emissions. In market-driven energy policy, if the cost of coal remains competitive, then it is difficult to imagine coal being displaced from this central position.

If we have the U.S., and presumably other nations, generating oil and gas from unconventional sources of tightly held fuel, then this practice generates a new array of environmental consequences. Sticking to the subject of climate change, some of these sources of oil have very high carbon emissions. Also we introduce new challenges in the management of methane, a highly potent greenhouse gas. Therefore, this good news for energy independence is bad news for the world’s climate.

World Energy Outlook 2012 does point out that renewable sources of energy are establishing themselves as an important part of the energy portfolio. Current projections are that by 2015, renewable energy will be the second largest source of electric power, and by 2035 renewables become comparable to coal. Note that is comparable to coal, not displacing coal, and this 2035-world has far more energy production than today. Again, with regard to climate change, the report states that subsidies for exploiting fossil fuels are six times as high as subsidies for renewable energies. Therefore, current energy policy does not suggest high priority to addressing climate change through low-carbon energy.

The International Energy Agency report also discusses the continuing unfolding of the role of nuclear energy following the destruction of the Fukushima nuclear power plant in the 2011 (see also, Earthquakes and Climate Change). A salient point from the report is, again, the apparent decreasing role of nuclear energy in displacing fossil fuels. Further, if nuclear will be having a decreasing role, then the role of renewable energy must increase at the intersection of climate and energy policy.

I will bring it back to the World 4 degrees warmer. In 2011 the International Energy Agency in its World Energy Outlook 2011 stated that the emissions path we were on was headed to a World 6 degrees warmer. In the 2012 report it is stated

“Successive editions of this report have shown that the climate goal of limiting warming to 2 °C is becoming more difficult and more costly with each year that passes. Our 450 Scenario examines the actions necessary to achieve this goal and finds that almost four-fifths of the CO2 emissions allowable by 2035 are already locked-in by existing power plants, factories, buildings, etc. If action to reduce CO2 emissions is not taken before 2017, all the allowable CO2 emissions would be locked-in by energy infrastructure existing at that time.” (That would be a goal of limiting carbon dioxide concentrations to 450 parts per million.)

If there is a path to near-term, dramatic reductions of greenhouse gases it is anchored on efficiency. The International Energy Agency has developed a strategy it calls the Efficient World Scenario. This “scenario is, rather, based on a bottom-up analysis of currently available technologies and practices and considers incremental changes to the level of energy efficiency deployed.” Like the Pacala and Socolow’s Stabilization Wedges, the proposed efficiency approach demonstrates that we do have the wherewithal to make a difference. The difference is the opportunity to develop energy-producing technologies that do not contribute to the accumulation of more carbon dioxide.

I paint here a known picture. It is crystal clear that we cannot address our energy challenges and expect to automatically address our climate issues. Short-term energy and economic issues will always trump climate change. We have here a technological development that by all indications makes global warming worse. We have great challenges in finding safe, secure sources of energy. Our easiest approaches to the energy security problem make the climate change problem worse. We cannot solve the climate change problem with fossil fuels – remember it is the accumulation of carbon dioxide, not the instantaneous emission of carbon dioxide that matters. All that is emitted stays with us for a very long time. Therefore, new technology that makes it possible to exploit unconventional oil and gas, which might make the U.S. energy independent, puts multiple stresses into the effort to address climate change. We have ingrained behavior and practice that continue to reward exploitation of fossil fuels more aggressively than renewable energy. Though the World Bank analysis comes to the conclusion that “a 4 degree Celsius warmer world must be avoided,” we have no energy policy, we have no climate policy, and hence, there is little indication that we will take steps to avoid that World.

In early December 2013 I was on a flight sitting next to a man who drives trucks in the Bakken Shale Oil Fields of North Dakota. In North Dakota they target, primarily, oil extraction. The man told me that they were mostly burning off the methane. He was thriving, growing a business. He was caring for his family and looking to the future. A curious statement he made was that the only problem was that all of money up there was coming from other countries. This just brings home our immediate energy future. We have made the exploitation of fossil fuels as cheap as apparently it was in the year 1300, when Marco Polo wrote of coal in China. We have beaten peak oil. The World wants these fossil fuels to run its economies. We want the jobs to run our economy. We cannot deny our drive to live comfortable lives, our drive for security. The ease of fossil fuels will keep their use growing. The reality is that our “built-in” climate change needs to accommodate the increment that will come from the emissions that cannot be denied.

r

A note on comments to the blogs: The discussion and information that I see in the comments on this blog in the past year have, for the most part, been amazing. I get the occasional note about trolls and denialists. I realize the frustration that some feel, but that is part of life. And compared to some places, it’s pretty productive at WU. The lists of documents, the links to articles, it is quite a resource. I have tried to figure out if the blog comments could be put into tumblr or some place, but as with many things, I am not smart enough. Hope you keep it up in 2014. Thanks.

Climate Change Greenhouse Gases

Updated: 2:42 PM GMT on January 15, 2014

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About RickyRood

I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.