Wait a Second…. You’re Telling Me That Global WARMING May Be Making our Winters COLDER? Please Explain.

Introduction

While I have been educated in English for most of my life, and even my iPhone settings are completely in English, I have always preferred reading the news in Dutch. As I was scrolling through NU.nl on a particularly cold Saturday morning, an interesting article named “Freezing cold in March: ‘we can expect these kind of periods more often’” (roughly translated), caught my attention. While the article does state that the future winters will know more (cold) extremes due to the melting of the Arctic, it lacked an explanation of why/how this occurs. Out of curiosity I continued to further investigate the topic with one question in mind, is our cold bitter winter season in the Netherlands ultimately caused by global warming?

Initially I hoped some other Dutch media source had shown an interest in the cold weekend as well. Unfortunately, only RTL news had published a video to show that it was 21 degrees 13 years ago, which was “newsworthy” due to the freezing temperatures experienced on the same day in 2018. How insightful. Naturally this post caused some climate skeptics to question global warming on twitter. If it was 21 degrees thirteen years ago and freezing today, global warming must be in reverse, right?

Just because we still experience cold episodes does not mean the climate isn’t warming. And for those of you who still misconceive a cold day as an excuse that global warming does not exist, feel free to read one of the many articles explaining the difference between weather and climate. Nevertheless, as this blog post will show, global warming may be able to explain both the cold and warm days we are experiencing.

Fast Warming Arctic

IMG_6749
Figure 1 Arctic Feedback Loops (Carana 2014)

It is no secret that human induced climate change is gradually warming our planet. NASA as well as many other research institutes, have indicated that notably the poles are warming much faster compared to the rest of the world. The American Meteorological Society  states that sea ice loss is one of the main drivers warming the Arctic via the ice-albedo feedback (figure 1: feedback loop #1). Albedo refers to the reflectivity of a surface. A high albedo indicates that more energy is reflected back to space, while a low albedo indicates that more energy is absorbed by earth. Ice has a higher albedo compared to open ocean, therefore, when ice melts more energy is absorbed and temperatures increase. However, data indicates that there is a greater warming in the winter compared to summer, which NASA attributes to energy transportation. However, NASA does highlight that further research is required to understand this energy transportation, which is a common conclusion in climate sciences.

Additionally, WFF notes that the Arctic’s permafrost (frozen soil) contains a significant amount of methane, a potent greenhouse gas. As the Arctic continues to melt, this methane is released from the soil, leading to additional warming. This is referred to as the Arctic permafrost feedback loop (figure 1: feedback loop #2), and is one of the many means by which the warming Arctic affects the global energy budget.

Warm Arctic –Cold Continent

The Warm Arctic – Cold Continent Hypothesis, a notion that fast warming Arctic causes the displacement of cold air to lower latitudes is, according to Cohen et al., increasingly being discussed within the scientific community. It is a rather controversial topic considering that warming has dominated the global temperature trends over the past decades. However, in winter, cooling trends have been observed across Eurasia and the eastern United States, while the Arctic rapidly warms.

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Figure 2: Polar Vortex explained (NOAA)

In order to comprehend the relationship between the warm Arctic and the cold winter episodes, it is important to understand the polar vortex. According to the New York Times, the polar vortex is a low-pressure system that rests over the North and South Pole. The boundary between the northern hemisphere vortex and the mid-latitudes is known as the polar jet stream, a fast counter clockwise moving wind. When the polar vortex is well defined (figure 2; stable polar vortex), it ensures that the cold air in the Arctic is well-contained. However, occasionally, the polar vortex weakens, which allows the cold air to escape to lower latitudes (figure 2; wavy polar vortex). This can be compared to opening and closing a freezer. When the freezer is closed there is no interaction between the temperature inside the freezer and the room temperature outside the freezer. When the freezer is opened cold air escapes from the freezer allowing warm air to come in, hence the room temperature decreases while the temperature in the freezer increases. However, when I leave my freezer open it starts to frantically beep causing me to close it, while a weakening in the polar vortex does not have such a warning system and can last weeks. Speculations have indicated that the strength of the polar vortex depends on the temperature gradients between the Arctic and the mid-latitudes. Due to the fact that the Arctic is warming much faster compared to anywhere else on earth, the temperature gradients is decreasing. This causes the jet stream to meander, weakening the vortex, moving cold air south and warm air north.

A very recent article published in Nature does note that “correlation does not mean causation”. Research concerning this phenomena is still in its early stages, hence, as long as this debate continues, this hypothesis is yet to be crowned as a theory.

Sudden Stratospheric Warming

It is plausible to presume that weakening of the polar vortex caused the extreme cold spell that hit Europe mid-February till early March. While this is definitely not a wrong assumption, the polar vortex did not just weaken, it actually split! A unique event known as Sudden Stratospheric Warming (SSW) was responsible for the split (and ultimately our ice skating adventures). SSW is defined by the The Irish Meteorological Service as a rapid increase in temperature in the stratosphere. The SSW is triggered by a disruption of the normal westerly flow due to natural weather patterns, or a disturbance in the lower atmosphere. This disturbance can lead to the wobbling of the jet stream as discussed earlier. If the “wobbles” break (like waves on a beach) they can be strong enough to significantly weaken or even reverse the westerlies to easterlies! The reverse causes the air in the stratosphere to collapse and warm due to adiabatic compression.

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Animation 1: wind patterns at 10 hPa 01/02/2018 (Earth 2018)
27-02-2018 wind
Animation 2: wind patterns at 10 hPa 27/02/2018 (Earth 2018)
27-02-2018
Animation3: surface temperature 27/02/2018 (Earth 2018)

The 3 animations clearly represent what happened during the cold spell in February 2018. The animations were obtained from the data visualizer Earth, an interactive platform that allows you to observe the winds of the polar vortex in great detail at different times across different altitudes. Animation 1 shows the wind patterns at 10 hPa on the 1st of February before the polar vortex split. Animation 2 shows the wind patterns at 10 hPa on the 27th of February, clearly showing how the westerlies have shifted to easterlies. Animation 3 demonstrates the surface temperature on the 27th of February, confirming that higher latitudes were indeed warmer compared to most of Europe! I highly recommend you to play around with Earth between the 1st and 27th of February, it is pretty amazing to see the polar vortex split! You may also want to check out 250 hPa to see the polar jet in action.

Of course the question remains whether SSW events will become more frequent due to global warming. While, a recent paper published in the Journal of Climate does insinuate that this may be the case, they do so very cautiously as such an idea is even more uncertain compared to the Warm Arctic –Cold Continent hypothesis.

Conclusion

Now you can go home for Easter and impress your family with stories about the polar vortex that NU.nl lacked to mention. I speculate that NU.nl did not provide more detail about why the warming Arctic will cause more chilly periods in the mid-latitudes because the topic is still poorly understood. Yet they weren’t afraid to make one final bold statement in their conclusion; within the next 8 years weather reporter Piet Paulusma expects an elfstedentocht (eleven city tour, a Dutch ice-skating competition). Fun fact about the Netherlands; whenever “cold” weather is discussed by the Dutch, the term “elfstedentocht” has to be coined. Therefore, I too feel obligated to make a final statement about the future of the elfstedentocht.

Being born mid-February 1997, I have never experienced an elfstedentocht. If these extreme cold periods caused by a warm Arctic are similar to the one we experienced in February, the intense cold wind will hinder ice formation (let’s not pretend like the ice we skated on last month wasn’t shady). While there were fifteen elfstedentochten in 20th century in total, the Royal Dutch Meteorological Institute (KNMI) expect only about four in the 21st century. Bottom line is: I wouldn’t count on this Warm Arctic – Cold Continent phenomenon to make an elfstedentocht happen. The fact is, the average temperature in 2018 will likely be another record breaking year despite our cold winter. Sorry to disappoint, but we have to continue to take a long hard look as ourselves in the mirror in order to change our habits and keep our elfstedentocht dreams alive.

 

 

 

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7 thoughts on “Wait a Second…. You’re Telling Me That Global WARMING May Be Making our Winters COLDER? Please Explain.

  1. I find this blog post very interesting! For another class I had to present the work of Wallace Broecker, a famous geochemist of the last century. He stated in his article “What if the conveyor belt were to shut down? Reflection on a possible outcome of the great experiment”, that global warming could lead to the shut down of the oceanic circulation (it’s is quite complicated to explain how it would happen so I am not describing the theory behind his idea, but you can read his short article to understand it yourself). This would lead to a glacial climate period similar to the Younger Dryas on a local scale, close to the Atlantic (so the Netherlands would be further cooling instead of warming with global warming). It is obviously a phenomenon that would take place on a longer time scale than the weakening of the polar vortex. Perhaps, the latter precedes the shutting down of the ocean circulation. Obviously, I do not know enough about either of the topic to make real speculation but it would be interesting to look into it!

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  2. While I was researching this topic I did come across several articles that mention the “new ice age” due to the thermohaline circulation shutting down. However, I thought it went beyond the scope of this paper, and therefore didn’t include it. nevertheless, it is definitely another interesting debate to investigate, especially because it appears to be very controversial! Thank you for raising this subject 🙂

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  3. Reblogged this on My view on climate change and commented:
    One of my students, Judith, wrote a blogpost on the Warm Arctic –Cold Continent hypothesis:
    “Due to the fact that the Arctic is warming much faster compared to anywhere else on earth, the latitudinal temperature gradient is decreasing. This causes the jet stream to meander, weakening the vortex, moving cold air south and warm air north.”

    There will be a new blogpost written by a student of Amsterdam University College (AUC) almost every weekday until 26 April on a topic related to climate change, energy, and sustainability. Check out the blog at https://auclimate.wordpress.com/

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  4. LAURIANENOI: Note also that if the Atlantic Conveyor currents shut down, the water in the North Atlantic would be redistributed somewhat. Coastal areas in the US/Canada and I think Europe (your professor will have to verify that) have lower sea level owing to a current-caused mound of swatter where these currents push. If that shuts down, there would be a more or less instantaneous spreading of that water raising sea levels by several inches. (I’m not sure how long an “instant” is in this case, but I imagine months or years?)

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  5. Judithnuria, thank you for an interesting and informative article. I hope your professor has prepared you for the possibility that there will be an interesting discussion in the comments, once your post has ‘escaped into the wild.’ Indeed, I may be one of the participants over at Bart’s weblog.

    There I will be persistently asking if we have evidence that the phenomena you describe so well are unusual and making much of the brevity of the historical record regarding them.

    Again, thank you for a very clear contribution to the climate discussion.

    Liked by 1 person

  6. Interesting blogpost, Judith! Very insightful and I agree: it is a pity that Dutch media (or media in general) spend so little time and effort on actually explaining the climate change workings behind possible weather events. However, I am not too sure if your conclusion about why media do not report on this is correct: “I speculate that NU.nl did not provide more detail about why the warming Arctic will cause more chilly periods in the mid-latitudes because the topic is still poorly understood.” Without a doubt, not all media have the experts in the house that know enough about this topic. But that is just a question of calling such an expert to explain it to them. I rather think that global warming and climate change are (still) seen as ‘leftist’ subjects and that this is a political choice. If people read about a weather event and the media platform immediately links it to global warming, they find this not objective an an extremely ‘leftist’ way of reporting – despite the fact that this is actually much more truthful and insightful. Also this is just a speculation of me, but I’d say that it is rather a question of politicalisation of the media, than laziness or ignorance. And for the specific case of NU.nl: they are more a kind of press bureau than a real news medium, they never give deep background articles or extensive reporting of events. However, this should not be the case of other media platforms…

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  7. @maxvangeuns I don’t disagree with you, I just didn’t think of it. Thank you for your comment 🙂 it’s nice to see how all our different backgrounds and the knowledge and understanding we have of the world can contribute to each other’s blog posts!

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