dimanche 10 juin 2018

132- Bad weather -11- Polar vortex


This year 2018 has brought a lot of situations of bad weather, here in Andalusia, as in many other places on the planet.
It's not so much the cases of bad weather that is remarkable, but their sequence, their frequency and their intensity, and of course their consequences. In the case of the peachtree here, we can talk about the formation of multiple fruits, consequence of the heat in autumn, about the difficulty for the plants to go dormant, due to a never-ending autumn, about the damage of spring frost, about damages of wind friction on young fruits, hail damage, etc.

Since June 2017, I mean in the space of one year, we can quote, in order, a particularly hot summer, breaking the record of days to more than 40ºC, a very dry autumn, hot and long, a winter without rain and very cold for the region, spring frosts, then from the end of February, abundant and repeated rains, accompanied by strong winds and numerous hailstorms, a month of May particularly fresh and a lack of light, and a month of June that starts under the sign of freshness and humidity.
Years follow each other and are not really alike. They are so different that my historical data, accumulated since 1974, don't serve me much.
As I have already told you, mathematical models are usually very useful for predicting and anticipating.
This ability to anticipate is used to predict dates and severity of certain phytosanitary risks, to predict the dates of harvest, to make adjusted irrigation inputs, to set the dates of sowing, etc.
These models represent an essential element in environmentally friendly farming methods, whether it be integrated production or all forms of organic farming.

Agriculture is based on natural cycles, themselves conditioned by meteorology. Weather disturbances directly affect the behavior of plants and animals, with potentially serious consequences for food production.

Picture of my own

I note here that 2018 is the third year in a row showing tangible signs of an evident climate change. An atypical year from time to time has always been the rule. A prolonged dry spell over several years, too. But such a succession of diverse anomalies is very remarkable.

So far, we have been told that global warming is difficult to appreciate locally, that it is the global data that must be taken into account. And until 2015, we could see it, with a variability, all in all, quite usual.
But this series of atypical three years becomes worrying. It seems that we are entering a phase, also announced by meteorologists for a long time, that of extreme phenomena.

An article published last March in a Mexican digital magazine brings us some of the explanation of this situation, and invites us to prepare ourselves to face serious climatic difficulties in the decades to come.

The weakening of the polar vortex causes extreme cold in Europe
Friday, March 2, 2018

The same phenomenon, which is linked to global anthropogenic warming, affected our country last January

Figure 1: The graph shows historic temperature values ​​for this time of year in the Arctic. The red curve corresponds to the temperature during the first months of 2018, the white curve the expected value. This phenomenon creates a historic thaw in the region surrounding the North Pole.

By :
Dr. Alfredo Sandoval Villalbazo, Coordinator of the Physics Departmental Service Program of the Department of Physics and Mathematics of the Ibero-American University of Mexico City.
National Researcher Level II (SNI)

In 2014 was published in the journal Nature a study in which was analyzed the effect of the Arctic warming on the behavior of cold air currents that exist in this region of the planet (1). The authors of the study showed that this warming would significantly alter the balance of the polar vortex, to the point that very cold air masses would eventually descend to the continents, producing extreme cold at mid-latitudes.

Four years later, the effect predicted by the authors of this study has been dramatically confirmed, affecting the eastern coast of the United States, northeastern Mexico (2) and more recently Siberia and Western Europe, where dozens of deaths have been reported due to extreme cold.

The scenario was also anticipated, more urgently, in a recent scientific communication sent to the North American Meteorological Society; the latter was subjected to rigorous arbitration in May 2017 and published online on 1 February 2018 (3).

High levels of carbon dioxide from human activities such as fossil fuel combustion and dietary habits have resulted in the Arctic recording a much higher rate of warming than the rest of the world (4).

During the months of January and February 2018, temperatures recorded in the Arctic exceeded by 20ºC their historical normal values ​​(see Figure 1). The relatively warm air currents that penetrated the northern polar circle acted as a dagger that resulted in two large masses of cold air that, when descending to the continents, caused unusually low temperatures, first of all in North America and then in Europe (see Figure 2).

Figure 2: In this image, developed by the Institute of Climate Change at the University of Maine on February 10, 2018, we observe the polar vortex cut in two parts. Temperatures around the North Pole are about 20ºC above their normal value (red region near the pole), while in Europe and North America temperatures are significantly lower (blue regions).

Since the beginning of February, the polar air mass in Siberia has begun to move towards Western Europe forming what is known as the "Eastern Beast", which has caused impressive snowstorms even in areas very south of Italy (see Figure 3).

The consequences of the thaw in the Arctic are not limited to episodes of very cold winters that can cause irreversible damage in vulnerable communities. "What's happening in the Arctic does not stay in the Arctic," but alterations in models of extreme atmospheric currents such as hurricanes with high intensity OR deadly heat waves.

In addition, there have been changes in the physical properties of oceans that affect ecosystems, causing migration of many animal species and in some cases extinction scenarios.

 Figure 3: on this image of early March 2018 we see the polar vortex divided, with the Arctic abnormally hot, very low temperatures in Europe and moderately low temperatures on the west coast of the United States. The colors indicate the deviations from the mean values ​​for that time of the year.

Due to the unusual characteristics of the climatic phenomena recorded in 2018, many means of communication abroad have had to concentrate their efforts to provide an understanding of the phenomenon of the weakening of the polar vortex (5). It is ironic that these media have had to resort to information known for years, published in high-level scientific journals, but until then gone unnoticed.

The concentrations of greenhouse gases will not decline in the next decades until the levels recorded at the beginning of the 20th century. It is therefore obvious that we will continue to witness extreme events related to global warming. It is only thanks to a better rapprochement between the scientific community, the society and the different sectors of the governments that we will be able to successfully face the scenarios derived from the ecological crisis that humanity is going through."

References :

(1)          Baek-Min Kim , Seok-Woo Son, Seung-Ki Min, Jee-Hoon Jeong, Seong-Joong Kim , Xiangdong Zhang, Taehyoun Shim & Jin-Ho Yoon,  “Weakening of the stratospheric polar vortex by Arctic sea-ice loss”,  Nature Communications 5, 4646 (2014)

(2)          A. Sandoval-Villalbazo, ¿Por qué el calentamiento ártico agudiza el frío en nuestro país?, Prensa Ibero, 16 de enero de 2018.

(3)          Kretschmer M. , D. Coumou, L. Agel, M. Barlow, E. Tziperman & J. Cohen,  2017: “More-persistent weak stratospheric polar vortex states linked to cold extremes”,: Bulletin of the American Meteorological Society 

(4)          A. Sandoval-Villalbazo, “ANÁLISIS: Ritmo de calentamiento en el Ártico, superior al resto del planeta”, Prensa Ibero, 2 de mayo de 2017.

(5)          Some international media notes in which are included descriptions of polar vortex behavior in the context of the cold in Europe are:

The magazine Forbes

The paper ABC in Spain

The British tabloid The Sun

The paper Financial Times

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