Over the past decade or so the problem of climate changes has been in the focus of practically everyone's attention-from scientists to laymen. Taking part in disputes on this vital subject have been not only experts, but also politicians of the highest rank. Our correspondent Rudolf Balandin has been able to interview Acad. Yuri Izrael, Deputy Chairman of the Intergovernmental team of experts investigating the problem of climate changes. We now reproduce this interview:

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Mathematical models of global climate dynamics without taking into account technogenic factors (a) and taking them into account (b) in comparison with the real changes observed.

- Yuri Antonievich, how true is the claim that it is us, people, who have precipitated the global warming?

- In fact, the situation is not as simple as it appears at first sight. Major climate changes are produced by natural causes and these are not easily distinguished from those resulting from human activities. According to information provided by the Intergovernmental team of experts, during the 20th century the mean global temperature at the surface of the earth rose by 0.6 +/- 0.2°C. This has been accompanied by rising levels in the atmosphere of what are called hothouse gases which "lock up" the infrared heat of reflected solar radiation. These gases include carbon dioxide, methane, nitrous oxide and tropospheric ozone. These are produced by the burning of organic fuels or in the course of farming activities. According to mathematical modeling results, the currently observed climate warming can be most accurately described only if both the natural and the anthropogenic factors are taken into account.

- The latter are usually described almost exclusively as industrial discharges of carbon dioxide?

- Their volume is really great and keeps growing. But there are also other gases which provide no small contribution to this process. For example, the growing levels in the atmosphere of nitrous oxide, connected with land cultivation, boost the hothouse effect by 6 percent. An impressive amount, and even more so because this gas is quite passive, or inert, does not enter into reactions with other gases and therefore keeps accumulating from century to century.

- But then green plants actively assimilate carbon dioxide. One would think that the greater its levels in the air, the better it is for the plants because it stimulates their growth. The burning of coal releases the carbon which used to accumulate in wood and timber during the early geological epochs. And if there was no destruction of forests by man, the hothouse effect would not have been so dangerous. But is that really so?

- Forests in general are having a beneficial effect upon both-our environment and ourselves. People are quite right in calling forests the lungs of our planet. This being so, our task is to preserve and replenish our forests. And that is easier said than done. Some billion of people use firewood every day. And it is up to us all to decide whether or not this is too much or too little. As for Europe, it has practically no forests left as compared with plenty of them in the past. Forests have been felled for peaceful and military purposes, for industrial needs, residential construction and simply scorched to clear land for farming.

- What about the impact of forest fires upon the global climate*? On the one hand, smoke and ashes make the atmosphere less transparent, which means cooling it down and preventing solar rays from heating the surface of the earth. On the other hand, this produces additional

* See: "Burning Problem", Science in Russia, No. 3, 2004 - Ed.

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Temperature fluctuations on the earth surface: above - over the past 140 years on the whole planet; below - over the past thousand years in the Northern hemisphere.

Diagram of carbon circulation in biosphere.

amounts of carbon dioxide which boost the hothouse effect. So, what prevails over what?

- There is no denying the fact that forest fires release into the atmosphere plenty of carbon oxide. As for discharges of sooth and ashes, much depends on the color of these particles: lighter particles reflect solar rays and dark ones absorb them. On the whole, forest fires provide but an insignificant contribution to global climate changes.

- Why people mention, but seldom, among the hothouse gases the common water vapor, or steam?

- The reason for that is simple: its levels in the atmosphere remain approximately unchanged. And the levels of carbon dioxide have risen by 31 percent over the past century. The difference is great. And at the same time water steam is constantly in circulation, obeying almost exclusively the laws of nature alone, and man has practically no significant control over that, although the situation can be different in some places. For example, near thermal and nuclear power stations with large cooling ponds, or near water reservoirs.

- In discussion about climate changes, they often use mean global values. But there can be considerable differences with regard to particular territories: every country, city or region are located within some specific environments. This being so, should we not focus primarily on regional changes?

- Yes, this is an important aspect and it is, naturally, taken into consideration. It has been established, for example, that during the past century there was an increase in the levels of atmospheric precipitation on most of the dry land, especially in Scandinavia, North America, in the north of Siberia and in eastern Australia. And it has dropped in the Mediterranean and south of Sahara. According to forecasts, continued warming will affect climate in the United States where there will be more hot weather days and droughts. As for our own country - the coldest in the world-experts believe that climate warming will produce a favorable effect.

- But is that not a naive, or simplified view? We all know of the problem of rapid degradation of permafrost...

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- The answer to that is both-yes and no. But warming of only one degree С during one winter month in European Russia will help save about 1 mln tons of fuel ой, mazut. The figure is really impressive. But there can also be negative consequences in some regions, above all for farming. And we do have areas with periodic droughts. Say, 80 years ago there were two years of terrible droughts in the Povolzhye Region. And as a matter of fact, it has always been a zone of what we call "risk" farming.

- What about the plight of the Aral Sea and its negative effect on Russia's southern regions?

- Yes, this vast territory is in a tragic situation. Desertification continues there and it affects the surrounding territories, including the Southern Ural, Povolzhye and Northern Caucasus which will all suffer from dry winds. IncidentaUy, I headed a government commission 20 years ago which prepared proposals for improving the natural conditions of the Priaralye Region and for saving the Aral Sea. But then there came the year of 1991 and all work was stopped.

- Some people say that it was the "human factor" which was responsible for upsetting the water balance and spoiling the climate in that area. Do you agree with that view?

- Yes, I do. What happened there is a "man-made" catastrophe. The sea was "supplied" by two rivers which were made to supply more and more water to the local farming. As long as the level of "water supply" to the Aral Sea did not sink below 50 km³ /year, the level of the sea was maintained. But then this level dropped by 2 - 3 times because of new land reclamation projects in the upper reaches of the Amu Darya, the sea started drying up in an irreversible way. In what remains of it today water salinity is twice as high as in the ocean. There is practically no fish left, and back in the past there used to be a big fish-processing plant. The Amu Darya delta used to be a place of unique natural beauty...

- What about Lake Aral? Can it be preserved?

- Yes, it can, but that would require considerable expenses. For example, there were plans of digging two canals parallel to the Amu Darya in order to collect "used" water from the fields and to prevent its leaking into the sand, or feeding some small lakes. Yes, this water will be polluted with pesticides, but it would also "save" the sea and prevent a local climate catastrophe.

- One gets the impression that human activities produce the greatest impact on regional climates, producing sharper contrasts. In some regions there are large water reservoirs, in others-giant megalopolises and industrial regions. Practically speaking, this shattering "pressure " on the climate will keep growing?

- Yes, this is about what we see around us now. On the other hand, our "picture" or image of things around us is very subjective. When temperature outside suddenly drops, we start talking about a "cold spell" and then there comes summer heat and we complain of warming.

Growing weather contrasts in the second half of the 20th century and world economic losses from extreme weather conditions.

Forecasts of changes of some global parameters following a reduction of CO₂ technogenic discharges.

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- But there are statistics of global economic losses from such extreme weather phenomena. And the scale of such losses rose sharply during the last decades of the 20th century.

- The diagram of statistics you've mentioned now was prepared by an international team of experts of the Intergovernmental Organization of which I am a vice-chairman. It represents several thousand of experts from different countries. And we are not inclined to associate the above "regularity" with the consequences of human activities. It can be the result, at least partially, of natural processes. Weather contrasts can increase in the future, although we do not expect any catastrophic climate changes over the next few years. Devastating floods, hurricanes, tropical cyclones and droughts- these are all natural phenomena which occur periodically in different regions of the earth. So far we have no any tangible reasons to say that they have become more frequent or more dangerous because of the global warming produced by the hothouse effect.

- Over the past half a century the level of carbon dioxide in the atmosphere has been growing steadily and the most convincing explanation of that are growing technogenic discharges. At the same time global warming is taking place and also, as we said before, world economy is suffering growing losses because of weather anomalies. Is there some connection between all these factors?

- This is exactly what most experts believe. But problems of science are not solved by a majority vote. What we need are tangible proofs and these are really hard to get. And we do have many indications that these processes are really interconnected. For example, world energy resources are still based on the burning of organic fuel. And that means that the levels of hothouse gases in the atmosphere will continue to rise, at least during the next few decades, and the global warming will continue. However, I repeat that in my view there is no global climate cataclysm in sight.

- Then there is another question: should our country sign as quickly as possible the Kyoto Protocol (1997) on limiting discharges of carbon dioxide? Because this is one of the ways of restricting the technogenic warming and the associated negative natural phenomena.

- The aforesaid Protocol is the subject of debates which are not so much of a scientific, but rather of political nature. What happens if it is ratified by all of the remaining countries and above all the United States and Russia? Let me remind that present in the atmosphere now are 370 molecules of CO₂ per one million molecules of all gases (at the start of the 20th century that number was 280). And then, according to calculations, some 10 - 12 years later this figure will be 390. That means that obeying the Protocol norms will reduce that number only by a figure of 2!

- Is the "gain" really so small? Can there be some error in calculations?

- These calculations are not too complicated and can be easily verified. The total volumes of the used organic fuels are well known. In the final analysis in keeping with the Kyoto Protocol we gain only 0.3 percent. And in order to stabilize the concentration at the level of 550 molecules of carbon dioxide per one million of all gases it is nee-

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Rising CO₂ levels in atmosphere according to observations on the Hawaii.

essary to reduce its atmospheric discharges by 2 to 3 times right away. This is several times greater than the provisions of the Kyoto Protocol.

- But why the problem of signing the Protocol is so acute?

- In that respect a key factor is a purely psychological nature. The argument is - let's just begin from the beginning. The protocol has an article for a redistribution of quotas under which you can pollute the atmosphere above the norm and pay a compensation to one or several countries which do not make full use of their quotas. Thus the ideas of the Kyoto Protocol are advertised, while ecological climate problems are left in the background. And that is apart from the fact that it is yet to be proved that global warming is dangerous for mankind.

- During some geological periods on this planet it was much warmer than it is today and there were no great contrasts between the natural zones. Could it be that we are now approaching a similar situation, which is not bad at all?

- Until now scientists have not established the upper limit of the level of carbon dioxide in the atmosphere which would be quite safe for our climate system. For example, in the Carboniferous epoch, 300 mln years ago, its concentrations were 10 times greater than now. And there used to be splendid forests around! What remains of them are giant coal fields. Of course it is really hard to say how comfortable people would feel in those conditions. But they were beneficial for the biosphere.

- You are referring to facts from historical geology and paleogeography. Which means that the problem of global and regional climate changes is of a complex nature and calls for combining the efforts of specialists in different fields: geographers, geologists, mathematicians, ecologists, etc. But is this kind of cooperation really possible?

- There is an academic program providing for the coordinated efforts of competent representatives of different areas of science on this general subject. And there are also respective international teams of experts. In the autumn of 2003 Moscow was the site of the World Conference on Climate Changes which was attended by more than two thousand participants. Our scientists reported on our achievements which remain at a high level. Today there is a seminar under the RAS President which is dealing with the aforesaid range of problems.

- After discussions with senior specialists of the RAS Institute of Mathematics* I got the impression that Russian experts are more willing to participate in international rather than national projects. Or did I get a wrong impression on that score?

- In many cases one can work more effectively with foreign colleagues because they have a greater computer potential at their disposal and considerable means. Let me quote just a couple of figures: US federal allocations for the program of climate studies were 2 bin dollars, as compared with our own which is only 6 - 7 mln rubles. Simply put two and two together and you will get the answer to your question. But in any case, close cooperation with foreign specialists yields good results and is mutually beneficial. And it is quite natural that the problem of global warming has to be tackled by our combined efforts at the theoretical and also the practical levels.

- And could it be so that for improving the climate on our planet we should focus on forests preservation and reclamation instead of running in circles around the problem of reducing technogenic discharges of carbon dioxide?

- To begin with we need a comprehensive scientific analysis of the mechanism and causes of the observed warming. Everything must be done for the preservation and restoration. This win help to improve not only our climate, but the whole range of natural conditions. This is inseparably linked with the destinies of our human race as a whole.

We have to study the potentialities of the biosphere and our climate system to determine the ultimate "safe" concentrations of hothouse gases. In order to prevent any adverse effects of climate changes it is necessary to bear in mind that, apart from limiting technogenic discharges of hothouse gases, there is yet one more factor to be borne in mind-adaptation of all living beings to these changing conditions around us.

* See: V. Dymnikov, "Computer Models of Terrestrial Processes", Science in Russia, No. 3, 2004. - Ed .

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