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fires and aerosol content. A similarity has been found out between the inter-seasonal
variability of the number of
fires and dynamics of the Julian-Madden oscillation
(Kondratyev and Grigoryev 2004).
As McConnel (2004) has justly noted, so far it remains unknown why some
forests have suffered fragmentation, degradation and loss of biodiversity, while
other forests remain in a good state and even expand. There is no doubt that an
increase of population size, further enhancement of the scale of market relations and
an intensive development of various economic infrastructures belong to important
factors of the observed deforestation. Factors acting against these processes are
measures on nature protection favoring the preservation of forests. Finally, the
forest cover dynamics is determined by a complicated and interactive totality of
such factors as biogeophysical processes, increasing population density, market
relations, various disturbing forcings (forest
fires including) and institutional
microstructures.
Forest
fires affect the formation of global carbon cycle. Really, global scale of
forest
fires have recently become equivalent in area to the territory of Australia. The
atmosphere receives almost 40 % of global CO
2
emissions, 90 % of forest
res
being of anthropogenic origin. This means that the balance of natural factors is
heavily broken, and the laws of natural evolution are strongly violated.
Among other natural phenomena affecting the environmental dynamics are
volcanic eruptions, dust storms and thunderstorms. One of the consequences of a
large-scale volcanic eruption is a powerful atmospheric pollution, which can lead to
a climate change in some regions or even on a global scale. So, in particular,
aerosols connected in many respects with emissions of sulphur dioxide during the
1991 Pinatubo eruption have led to a global decrease of temperature in the lower
atmosphere in 1992 by about 0.5
C. Also, it was noted that in 2 years the level of
the global ozone content decreased by 4 % compared to the preceding 12-year
period. And though during the last century there were no drastic climate changes
due to volcanic eruptions, in the historical aspect such situations did take place. So,
73,500 years ago due to the Toba eruption on the Sumatra island, the global
atmospheric temperature decreased by 3
°
−
5
°
C. The area of glaciers increased and
the Earth
s population decreased (Oppenheimer 1996). As a result, 600 volcanoes
existing now on Earth can, in principle, be a global threat to population, since they
can seriously change climate and affect thereby further development of the NSS.
Dust storms occurring in places with dust and strong winds, like volcanoes, play
a similar role in the environmental change. Dust propagates at great distances
affecting negatively plants and soils as well as causing a strong pollution of the
lower atmosphere for long time periods. In the regions with a thin vegetation cover
and arid climate, dust storms take away the fertile soil layer damaging thereby the
plants. Dust storms occur periodically, for instance, on the plains of Central and
Western states of the USA during heavy hurricanes. Sometimes they last for several
days, raise dust up to 1.5
'
6 km, and transfer it at hundreds
and even thousands of kilometers towards the Atlantic Ocean. Catastrophic dust
storms are connected with destruction of the soil-plant cover in steppes and par-
tially-wooded steppes, as well as in the regions of intensive agriculture. Along with
-
1.8 km and partially to 5
-
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