The biggest stone is nothing else than the Tungus meteorite that landed in Siberia on June 30th, 1908. By changing the concentration of ice crystals in the upper layers of the atmosphere, it damaged the structure of high altitude clouds in the mesosphere that normally reduce the amount of energy that reaches the surface of the Earth.
According to this theory, the nuclear tests in the atmosphere between 1940 and 1980 played the opposite role than the meteorite and contributed to cooling. Shaidurov predicts that the warming will start to decelerate.
The Reference Frame is not able to identify or check the right answer but agrees with Shaidurov's thesis that water causes most of the greenhouse effect in the atmosphere - the crucial role played by water was already known 150 years ago to the Irish scientist John Tyndall - which is why water should always be the primary compound found in the atmosphere to be looked at.
More details can be found e.g. in this preprint:
Although Shaidurov could be viewed as a climate skeptic in the sense that he is convinced that carbon dioxide is not primary, he reprints the hockey stick graph in his preprint.