According to a new study, the current global warming tendency is not driven by the burning of fossil fuels but by a natural event that changed the distribution of water vapors in the atmosphere. Water vapor are the main cause of greenhouse effect, having much more influence on the temperature than carbon dioxide and methane. In the same time, they are virtually completely outside of our control. The studies that claimed the importance of carbon dioxide and methane assumed that the levels of water vapors are unchanged. However, according to Vladimir Shaidurov of the Russian Academy of Sciences this is not so.
According to the Russian scientist the event that propped up global warming was the Tungus Meteorite that struck Earth in a remote part of Siberia, northwest of Lake Baikal on the 30th June 1908 (known as the Tunguska Event). This has released as much energy as fifteen one-megaton atomic bombs and blasted an enormous amount of dust into the atmosphere. Shaidurov suggests that this explosion has caused a "considerable stirring of the high layers of atmosphere and changed its structure."
According to him, this event had a dramatic impact on the tiny ice crystals that can be found at different altitudes in the atmosphere. The reason why water vapors and ice crystals are so important is that they determine what types of clouds form and at what altitudes. In the end, what counts most is the reflectivity of the clouds. Even a small change in the clouds can produce large changes in temperature because more or less sunlight reaches Earth's surface.
In order to prove his assumption concerning the Tunguska Event he looked at the temperature record over the past 1000 years. He has found a constant and slow decline in the temperature until around the meteorite strike. After the event one can see a sharp increase of the average temperature (see picture below). This increase has stopped only during the time of the nuclear tests in the atmosphere.
Shaidurov writes: "From the standpoint of atmosphere hypothesis the nuclear tests in the atmosphere are opposite to consequences of the Tungus meteorite. When a nuclear charge explodes at the Earth's surface or in the atmosphere, the shock wave vents water vapor from the troposphere to the stratosphere through tropopause. For some period (aprox. 3 years) water vapor in the stratosphere and aerosol, and dust in the troposphere and stratosphere suffice for the defense of the Earth from solar radiation. But then all gradually settled, and global warming continued."
Of course this does not mean the nuclear tests in the atmosphere were good - the entire Earth is a little bit more radioactive because of those tests! (There were some eccentric scientists who proposed the use of thermonuclear bombs against hurricanes: one could detect the hurricane from satellite and than throw an H-bomb in its center literally blowing it off before it got very large or near the coast.)
Moreover, Shaidurov explains that the levels of carbon dioxide and methane, the other two greenhouse gases are not the cause behind global warming but the effect of global warming. That this might be so has long been speculated, because global warming seems to have preceded the increase in carbon dioxide and methane. But Shaidurov also explains the mechanism:
"The point is that the average increase of land and ocean temperature produces higher average absolute humidity. In its turn, this raises the assimilation ability of the atmosphere even at constant content of carbon dioxide. But increasing the average ocean temperature is responsible for lower water solubility of carbon dioxide, which then arrives in the atmosphere. Moreover, increase in land temperature is responsible for growth of bogs, at least in Northern Russia, due to the removal of permafrost deep down. The rise in area and activity of bogs leads to more active production of methane. Thus, a self-stimulated process was launched for the increase of average temperature of the Earth's surface. Therefore the rise of greenhouse gas concentration is more a consequence of warming but not a main reason."
Therefore, there exists a positive feedback mechanism at work: the Tunguska Event has changed the distribution of water vapors and ice crystals in the atmosphere (the nature of the clouds) and has started the global warming; global warming produces an increase in the levels of the other greenhouse gases such as carbon dioxide and methane, and these in turn also contribute to the increase in global warming. However, the CO2 and the methane are negligible compared to the water vapors. A rise of just 1% of water vapor could raise the global average temperature of Earth's surface more then 4 degrees Celsius.
As Andrew E. Dessler of the Texas A & M University writes in 'The Science and Politics of Global Climate Change': "Human activities do not control all greenhouse gases, however. The most powerful greenhouse gas in the atmosphere is water vapour. Human activities have little direct control over its atmospheric abundance, which is controlled instead by the worldwide balance between evaporation from the oceans and precipitation."
It is worth noting that attempts to reverse global warming, such as the Kyoto Protocol, have centered on controlling and even reducing CO2 emissions. But, if Shaidurov is correct, global warming is a natural phenomenon on which we have little impact or control.