Climatologist, explained why the March had been warm, and may — cold in Russia
MOSCOW, 18 Jul — RIA Novosti. Academician Igor Mokhov, Director of the Institute of atmospheric physics RAS in Moscow, Professor of Moscow state University and MFTI, described how, due to the current abnormal weather conditions, as climate change affects extreme weather events and explained what the Land is worth to expect in the future.
One of the consequences of global warming are considered to be the so-called extreme weather events — heatwaves in the winter or cold in summer, heat wave, the week-long torrential rains, droughts and other phenomena associated with the “wrong” weather. For example, the flood in Krymsk in 2012 and is now considered one of the most striking examples of such phenomena.
How do you think today, many climate scientists, almost all such disasters are associated with reorganizations in the climate system that have occurred in recent years due to the growth of average air temperatures, the surface of the water in the oceans and associated changes in the motion of currents in the ocean and winds in the atmosphere.
— Igor Ivanovich, what is the relationship between extreme weather events that we have seen in recent months and climate change? Why their frequency has increased markedly in recent years?
— Statistics of extreme events, of course, linked to climate and its changes. When the climate changes, changes and anomalies. Changing the frequency, intensity, and duration of extreme weather / climate events. Extreme events, although the accumulated statistics on them can be still insufficient, are important indicators of what is happening, often obvious, changes. The increasing frequency of extreme events under global warming is associated not only with temperature changes but also with changes in atmospheric circulation and the hydrological regime.
— Where is the boundary between “normal” manifestations of the weather, fit into the General trend, and extreme weather events?
— There are different criteria for the selection of extreme events. Often used the condition of exceeding the variations of the climate variable is two standard deviations. It should be borne in mind that the distribution of climate variables, generally speaking, are not normal. And extreme events are associated with “long tails” of distributions. Thus, the criteria for evaluation differ for different processes. For example, for agriculture important in certain temperature ranges for vegetation. In addition, it is essential to humidity. At the same time for destruction of the crop is short of frost under favorable medium.
Of course, if we consider the season of one particular year, you can only talk about anomalies and fluctuations. But the statistics for the last decades and staatengemeinschaft the manifestation of a global trend with increasing numbers of such events, which is especially important in Russia in the last decade. This is due to the fact that Russia is a Northern country, in our regions the variability is several times stronger than at the global level.
As for the last years, in the common century warming is superimposed a number of natural climatic cycles with a period from several years to decades. Overall, the last decade was the warmest, according to observations from the mid 19th century, and in 2016, before 2015, was an absolute record.
The current year should not be as record — while he claims to be second only to last year. Why it is inferior to 2016? This is due to the additional thermal impact of last year’s phenomenon, the El niño years of its formation in the tropics of the Pacific ocean are characterized by the strongest positive temperature anomalies at the surface of the Earth as a whole.
It all depends on how events will develop further. Now, in mid-June, the predictive model estimates indicate most likely continue until the end of the year a neutral phase of El niño. In General, the growth trend in global temperature continues.
— Fit the current cool spring and early summer and last year’s hot spring and summer in a normal natural climate variations or they can be recognize the consequences of anthropogenic global warming?
— This year in Russia we are impressed with the may weather continued in June. Thus, one should not forget that March was very warm for Russia as a whole. The strongest positive temperature anomalies were observed throughout the country.
Generally speaking, such fluctuations of climate, including cold may-June and a hot March, to be expected. Known because such recurrent phenomenon as the “cherry cold”. In the transition period between winter and summer climate can occur a kind of “beating” in the climate system, particularly associated with the transition through a temperature of about zero degrees when the melting of the snow cover. The presence or absence of snow cover greatly alter the reflectivity of the Earth’s surface, absorption of solar radiation and temperature. Thus, the formation of different regimes at this critical transition point.
The anomalous regimes are formed and at atmospheric blockings in the atmosphere of the middle latitudes. An example of this is familiar to all autumn “Indian summer” and episodes of extreme heat in summer or cold in the winter. Atmospheric blocking in the beginning of may this year was celebrated over the Atlantic. During such events the normal mid-latitude zonal transport in the atmosphere from West to East is blocked in the regions of the middle latitudes break the flow of cold air from the Arctic or warm air from the South.
In 2010, for example, in the European territory of Russia was the heat in the summer, and Eastern Europe had heavy rains and there it was colder than usual. The same thing happened in Western Siberia. Significantly, according to the model estimates global warming increases the risk of such phenomena.
Is it possible to predict many such events and to understand how much they will affect a person’s life, for example, the flood in Krymsk in 2012 or the floods in California this year?
— What is happening now, in General, expected us at the level of General trends. We 20 years ago on the basis of model calculations showed that the total warming due to the increase in carbon dioxide in the atmosphere, the likelihood of atmospheric blockings increases significantly over the continents, particularly in winter and spring, resulting in a strong cold snap. These fluctuations do not contradict global warming, and characterize climate variability, his “nervousness” on the background of General warming.
Observed phenomena strongly influence regional precipitation. When warming the atmosphere becomes more water-holding capacity, which increases the level of maximum possible simultaneous precipitation. Change of character of atmospheric circulation. The weakening of mixing in the atmosphere contributes to greater spatial inhomogeneity of the rain — somewhere it fall out too much, and where, on the contrary, they are not enough.
Now in the summer months in southern and middle latitudes of Russia manifested a significant trend of decreasing precipitation due to global warming. This is because the moisture is not effectively transferred to the atmosphere from the Atlantic into the continent, and in the future should be expected to increase this trend. It is reproduced in model calculations in the assessment of climate change.
— When people talk about extreme events, they often mean floods, high rainfall or drought. This year we are faced with hurricanes and sudden change in the weather. Are they also one version of extreme weather events or is it something else?
— All different manifestations of extreme weather and climate anomalies. Global warming is expected that, in General, the cyclonic activity in the atmosphere will weaken, but with an increased risk of the most powerful cyclones. In recent years, in Europe it is not uncommon to powerful cyclones, leading to casualties. And although they do not hold power to tropical storms, they have already started to assign names like tropical hurricanes. The formation of such cyclones is due to the increased moisture capacity of the atmosphere with warming. Currently over the Mediterranean and Black seas was powerful, organoborane cyclones.
The events in Krymsk in 2012, for example, was related to the fact that the surface of the sea was very warm. The temperature in the Black sea reached record highs, which contributed to the formation of intense convective processes caused the birth of a very powerful rain. It is expected that the risk of such processes in the future will increase.
— Can we predict long-term consequences of such extreme events to human and Earth ecosystems?
— Accurate climate prediction is fundamentally impossible. You can only talk about probabilistic estimates. The accuracy of the weather forecast in recent years has improved considerably, but it should be understood that there is a limit of predictability which, if exceeded, can only be assessed on the likely developments.
While long-term probabilistic estimates depend on many different processes and phenomena, for example, whether the developing El niño in the Pacific ocean. This problem cannot be solved only by improving supercomputers. Need to obtain detailed various information about the climate system, including satellite data and ground-based tracking systems, to expand data banks. It is necessary for more adequate understanding and modeling of the processes.
Many scientists believe that a prolonged drought in the middle East caused by extreme weather events, was one of the main causes of the Arab spring and conflict in Syria. Whether so it actually?
— It is obvious that all migration of people in human history have been associated with climate change. Modern events in the middle East have less to do with natural phenomena, as with political issues.