Late permian changes in conditions of the atmosphere and environments caused by halogenated gases

There are periods in the Earth's history when environmental conditions and the climate sharply changed. Some of such changes were accompanied by mass extinction of living organisms and a decrease in the conflicting scenarios of terrestrial and extraterrestrial events which led to such consequences. In particular, the most striking such episode belonging to the Late Permian is related to eruption of volcanoes in Siberia, the impact of a large asteroid, and climatic fluctuations caused by a decrease in the ozone concentration in the atmosphere. By the ratio of isotopes in sedimentary rocks, there was revealed a degradation of vegetation in that period, which was accompanied by an appreciable decrease in productivity of photosynthesis. The photosynthesis reduction resulted in a decrease in O2 and an increase in CO2 concentrations in the atmosphere and oceans. Volcanic emission of CO2 in Siberia in the Late Permian also contributed to a general increase in the CO2 concentration on the Earth. The change in the radiation budget, the warmed-up climate of the Earth, and aridization of some regions on the planet could cause mass extinction of living organisms.