  When analyzing the mean-year trend of the Earth's surface temperature for the
past 140 years one can discern two sections of monotone linear increase of
temperature during two last industrial centuries. The first one begins
somewhere in the period 1906-1909. The previous segment demonstrates a weak
decrease in the temperature trend, not increase. For explanation of this sudden
break we look for a phenomenon of cosmic scale during this time which could
have given rise to beginning of global warming with a significant probability.
On the 30th June 1908 Tungus meteorite exploded with the power of ~15 Mt TNT at
an altitude of ~10 km. Such an explosion could cause considerable stirring of
the high layers of atmosphere and change its structure in mesosphere. The
difference between this mesosphere catastrophe and atmospheric nuclear tests
that cause another break in the temperature plot is discussed. The purpose of
this report is to open the debate and to encourage discussion among scientists.
