Other
Scientific paper
Dec 2001
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001agufm.u42a0008r&link_type=abstract
American Geophysical Union, Fall Meeting 2001, abstract #U42A-0008
Other
1620 Climate Dynamics (3309), 1630 Impact Phenomena
Scientific paper
As shown by recent investigations, galactic cosmic rays (GCR) exert a considerable influence on physical and chemical processes in the troposphere, including development of cloudiness. More intense (less intense) GCR fluxes result in the increasing (decreasing)lower cloudiness (Palló Bagó and Butler, 2000; Marsh and Svensmark, 2000) and, as a consequence, in lower (higher) near-surface temperatures. Modulation of GCR fluxes can be caused by variations in solar activity (from days to thousands of years on time scale) and changes in the geomagnetic field (from hundreds to thousands of years on the time scale).The additive effect of these factors, together with effect of other climatic processes in the Earth's atmosphere (for instance, Henrich events), can lead to an abrupt climate change. Examples of the additive effect of changes in the geomagnetic field and solar activity can be the Younger Dryas cooling event and abrupt climate change around 2,700-2,800 years BP. Both these cooling events occured, as follows from proxy data, during the minimum of quasi-2,400-year solar cycle and , hence, Gothenburg and Etrussia geomagnetic exursions. These effects lead to enhancement of the GCR flux, and, hence, to colling of the lower troposphere. At the Holocene boundary, the additive effect of three factors contributing to climate warming was observed. The first was an abrupt increase in the geomagnetic field, which resulted in weaker GCR fluxes. The second factor was the growth in the activity of the 2,400-year solar cycle, which enhanced solar radiation and weakened GCR fluxes. The third was astronomical factors (the Milankovitch effect) which also contributed to climate warming. The effects of the factors mentioned above enhanced each other, which could lead to the abrupt climate change at the Holocene boundary. Analysis has shown that abrupt climate change events occure as a rule, if several helio-geophysical and climatic factors are acting simultaneously in the same direction. This work was supported by EC (grant INTAS 97-3100 and IC 15CT98-0123 EXTRATERRESTRIAL) and RFBR (grant 00-05-64921).
Dergachev Valentin A.
Gus'kova E. G.
Kolström T.
Morner N.
Raspopov Oleg M.
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