Weather is an inexhaustible source of surprises for us, but now sudden changes in it serve as a cause of concern, for many experts in the field regard them as a manifestation of the global climate change due to the steadily growing hothouse effect as a result of man's activity. And in this situation researchers deem it necessary to state their position. At the height of the unusually high temperatures in Moscow in January 2007, Academician Georgy Golitsin, director of the RAS Atmosphere Physics Institute, Academician Yuri Israel, director of the RAS Global Climate and Ecology Institute of Rosgidromet (the Hydro-Meteorological Service of Russia), Academician Vladimir Kotlyakov, director of the RAS Institute of Geography, and Vladimir Katsov, Dr. Sc. (Phys. and Math.), department manager of the Head Geophysical Observatory named after A. I. Voyevkov of Rosgidromet, met with Yuri Medvedev, a Rossiiskaya Gazeta correspondent, in order to offer most objective answers to questions of public concern.

стр. 103

Georgy Golitsin has recalled that the Intergovernmental Panel on Climate Change, set up under the UN auspices in 1988, issues detailed reports on all climate aspects once in 5 - 6 years and stressed that the materials reflect the official viewpoint with regard to global climate change.

Yuri Israel, deputy chairman of the said group, has pointed out that, in his colleagues' opinion, the global temperature will rise by 1.9 - 4.5°C, or by 2 - 2.5°C on a average for hundred years, so there are no grounds to expect global cataclysms. However, other specialists believe that the global temperature will rise by 1°C at the most. Even worse, their most irreconcilable opponents insist that the critical point has been passed, that the Gulf Stream will change its route, with the Scandinavian Peninsula and North America becoming ice-clad and the Arctic and Antarctic glaciers turning into water-in a word, humankind is certainly doomed.

Meanwhile, in the desire to find an optimal solution, we should bear in mind the basic law of nature's development - its cyclic character. In this connection Vladimir Kotlyakov noted that glacial periods were followed by floods on a regular basis, although those periods were quite different - from millions to hundreds and even to tens of thousands of years.* Consequently, we may definitely assert only this: we now live in the inter-glacial period, described as holocene, that has been in progress for about 11,000 years. The average temperature in the period reached its maximum values some 5,500 years ago, when it was 1°C higher than now, while at present climate cooling seems to be round the corner. Such is the climate's general tendency.

Yuri Israel** agreed with him and added a weighty argument in favor of his opinion: if the carbon dioxide concentration producing the hothouse effect drops below 200 molecules per million air molecules, an intensive glacial process sets in. This indicator is now equal to 380, and in the periods when the global temperature was approximately 10°C higher, the respective indicator was about 10,000. Climate micro-warming in the 20th century (the rise in global temperature of 0.6°C) is next to nothing as compared with the large-scale changes in global climate history such as thawing glaciers on the poles or glaciers making their way to the equator. However, Yuri Israel also warned that in the course of the past 100 years temperature in the Northern Hemisphere has been rising at a rapid rate, something unheard of in the past millennium. Regrettably, he added, we have got quite insignificant information on its dynamics in the earlier periods, so, we can hardly speak about the role played by the anthropogenous CO₂ concentration in the atmosphere.

Mathematical climate models built by various researchers, Vladimr Katsov believes, allow us to lay with a high degree of certainty a part of the blame for the climate warming of the past few decades at man's door. At the same time Kotlyakov mentioned a certain aspect casting a simple answer into doubt. The fact is that there were periods in the Earth's history when increased concentrations of hothouse gases followed a rise in temperature (no explanation has been so far offered to the phenomenon), not vice versa. In other words, it is still anyone's guess what is the cause or effect.

The researchers discussed both extraterrestrial and terrestrial reasons behind climate cooling on Earth. The angle of its rotation axis periodically undergoes a change of approxi-

* See: V. Kotlyakov, "Enviroment, Its Past and Future: Glaciology Bears Witness", Science in Russia, No. 1, 2001. - Ed.

** See: Yu. Izrael, "Threat of Climatic Catastrophe?", Science in Russia. No. 4. 2004. - Ed.

стр. 104

mately 1°, and this factor determines the day's length in Polar areas.* The orbit of the Earth's rotation around the Sun is not the same either, and in our days the closeness of the Earth to the Sun reaches its maximum in January and minimum in July. If that coincides with reduction in light day hours, we have a situation where snow does not thaw in the area within the Arctic Circle, with conditions provided for the onset of glacial periods. Volcanoes producing disulfide may also contribute to lower temperatures, for vast amounts of this gas rising to a 20-kilometer height serve as a screen shielding the Earth from solar radiation**. We know that 73,000 years ago the eruption of the Toba volcano on Sumatra led to the drop of almost 2°C in temperature, followed by the glacial period of almost 60,000 years.

Asked about the climatic changes to be expected by the people residing in Russia in the next 10 - 15 years, Dr. Katsov gave the following answer. "The shorter the periods the more unreliable forecast." For when we speak of some ten years, the more so about the next half year, not a hundred years, experts have to deal with the so-called long-term weather which constantly undergoes change, rather than with climate. The most powerful computers, working on the basis of the most complicated mathematical models of the atmosphere, cannot make a 100 percent probability calculation even for the next 10 days.

Nevertheless, Rosgidromet's long-term forecast until 2015 has been prepared. According to the forecast, temperature on the territory of this country will rise on the average by a few tenths of the grade in the next 10 years. As a result, the heating season will be reduced and the vegetation period, prolonged. And there is a greater degree of probability for anomalies and extreme phenomena to take place, with the growing incidence of floods, hurricanes, snow avalanches, high waters and droughts. Their number is growing, Dr. Karsov noted, on the average at a rate of 6 percent annually. Owing to the growing precipitation, especially in wintertime, especially high waters are expected in Arkhangelsk Region, the Republic of Komi, in the Urals, on the Yenisei and Lena rivers. Disastrous spring floods are possible in the Northern Caucasus and in the area between the Don and Volga rivers. Regrettably, there is much room for improvement in the sphere of forecasts for natural disasters, for they develop rapidly and on small areas. However, Rosgidromet's reequipment, carried out now with the participation of the World Bank, gives grounds for hope that the situation will radically change for the better by 2012.

The Governments of different countries display great interest in climate development trends, for in our days they are duty bound to adopt decisions for the long-term perspective. The RAS Atmosphere Physics Institute and the RAS Institute of Geography have assessed, jointly with Head Geophysical Observatory named after A. I. Voyeikov and the Moscow University Geographic Department, the consequences of possible climate warming for Russia's economy. Their conclusion was that practically all of the country's regions, except the South regions, would potentially gain from such a scenario. As to the people's general condition, the northward shift of the border of uncomfortable living conditions would have different results. For, according to Dr. Katsov, the periods of maximum high temperatures - the so-called heat waves threatening to man's health - will at the same time be more protracted.

But will man probably be able to control climate? Yuri Israel believes that the idea is quite realistic. Just as Paul Krutzen of the Max Planck Institute of Chemistry (Germany), who won the Nobel Prize in chemistry in 1995, Yuri Israel supports Academician Mikhail Budyko's idea formulated 35 years ago: if you reduce the temperature of the Earth's atmosphere by 1 - 2°C by pumping into the stratosphere, for instance, about 600,0001 of sulfuric acid aerosol and in this way reproduce the effect of reducing the solar radiation currently produced by volcanic eruptions, you may well expect stable climate cooling in the course of one or two years. Next, droplets reflecting solar radiation will settle on the earth's surface and the climatic situation will be restored. This idea should be thoroughly checked. The President of the Russian Federation has entrusted the RAS with the task of going on with the research.

Yu. Medvedev, "A Bomb for Climate in the Making", Rossiiskaya Gazeta, January 10, 2007

Prepared by Yevgeniya SIDOROVA

* See: Yu. Avsyuk, "Moving Pivotal Axis of the Earth", Science in Russia, No. 6, 2005. - Ed.

** See: V. Osipov, "Threats of the Elements". Science in Russia, No. 2, 2005. - Ed.