According to a report issued by the Inter-Government Group on problems climate changes, close to one bin animal and plant species will be on the brink of extinction by the year 2005 due to global climate warming. Among those on the "danger list" are polar bears - these giants of the North. According to British and Norwegian experts a rise of the mean annual temperature of only one degree C, makes polar bears lose 8 percent of their weight, which impacts their progeny. With an expected shrinkage of the ice cover in the near-Polar seas of 2 mln km² , polar bears will no longer be able to dwell in Greenland, the Hudson Bay and on Spitsbergen. In the view of a leading expert in the field - Dr. Yuri Dgebuadze, Deputy Director of the RAS Institute of Problems of Ecology and Evolution named after A. Severtsov, the traditional habitats of animals of the Southern regions will be spreading up to the north. The change will be especially apparent with fish and birds. The well-known common sprat from the Caspian and Azov seas has already "moved up' to Lake Beloye located some 600 km to the north of Moscow. In the Volga basin 20 percent offish species are "migrants" from the south - 5 varieties of Gobius, needlefish and even Chinese crab. Today one can find in the Moskva River some South-American fish and guppies.

Drying up in the steppe and forest-steppe zones are many lakes and "heat-loving" birds can now settle in areas which were too cold for them in recent past. Thus, storks can now be encountered in the Volgograd Region. But the situation is most trying new for big ground animals. In Central Asia and Kazakhstan, for example, poachers kill large numbers of saiga antelopes and the areas of their habitat are shrinking. Continued deterioration of the climate in the region can put an end to the existence of these animals in natural conditions.

Changes of the habitat are especially fatal for rare species. In Lake Baikal, for example, there dwell some 2.5 thous. representatives of endemic species. If the ecosystem of the lake is upset by the climate warming, many of these animals will disappear, like the Omul (Salmon omul) and nerpa (fresh-water seal).

But the greatest harm to wild life is caused by the contrasts and anomalies of weather. For many wild animals unusually warm temperature in early spring signals the start of breeding and multiplication. And the subsequent sharp chills can wipe out whole generations-nip them in the bud, as the saying goes. Most exposed to this threat are species which produce progeny once in lifetime, such as the Far Eastern salmon. Climate destabilization can do great harm to mammals like wolverines, musk deer, walruses and bisons which all have low birth-rates.

And it is not impossible that this "expansion of species" into new territories and areas of water will stimulate rapid evolutionary changes. Say, botanists were puzzled for several years by the advent of "unorthodox" plants which looked like northern and southern bur-marigolds (Bidens). And it was later established that the "newcomers" were "crosses" of these plants.

Nothing of this kind has so far been observed in the animal kingdom. For example, Canadian beavers brought to Finland later "spread out" into our Karelia where their European "relatives" dwell. But "mixed marriages" of the beasts have (so far) produced no viable progeny. Although that does not rule out the appearance of "hybrids" or mongrels.

And the global warming of the past few decades is not something absolutely extraordinary for this planet. Climate changes with major tides of cold and warm temperatures did take

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place in the past. Today the problem is different: technogenic human activities speed up such changes and have a negative effect on our natural flora and fauna, polluting and poisoning, or radically changing our environment. As a result hundreds of species (as was the case in the 20th century) ceased to exist and that was not because of the oncoming global warming. The population of musk deers in Altai was so "hard-hit" by poachers that the few "survivors" have to be cultivated at biological stations near Moscow.

In the opinion of Prof. Dgebuadze, the current relatively small changes of the climate affect above all the wildlife in what we call the extreme natural zones-deserts and semi-deserts. The scientist witnessed in Africa large flocks of zebras and antelopes perishing because of drying local sources of water. And things of that kind did happen in the past - which means that it is too early to speak about some irreversible changes in the biosphere.

Prof. Dgebuadze points out that: "Global warming "breeds" all sorts of speculations some of which simply "cover up" the commercial interests on major international producers. One such example is the undue emphasis on the negative effects of carbon dioxide discharges into the atmosphere. Arguments of this kind are a "stone" cast by atomic power people at their oil-industry rivals."

But say what you may, there is no denying the fact that climate changes in the forseable future will be causing more and more appreciable harm to the biosphere. Although there are no reasons to pronounce them catastrophic*. Plants and animals possess a great potential for accommodating themselves to environmental changes and moving over to new territories. But, say what one may, in our present technogenic world their destiny is in man's hands.

Newspaper TRUD, 2004

Prepared by Rudolf TIMOFEEV

* See article by Yu. Izrael, "Threat of Climatic Catastrophe?" in the present issue. And also: V. Dymnikov "Computer Models of Earthly Processes", Science in Russia, No. 3, 2004. - Ed.

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