Ecoinformatics Problems of Global Climate Change - New Ecoinformatics Tools in Environmental Science: Applications and Decision-making - page 424

In this context, Bengtsson (1999) discussed the progress in numerical climate
modeling in three directions. A successful accomplishment of the TOGA program
has made an important contribution to provision of the transition to operational
forecasts of the seasonal and inter-annual variability considering the prescribed
SAT changes in the tropics, which has determined the critical importance of reliable
SAT data. The second of these directions is connected with numerical modeling of
climate change on scales of decades and longer and especially with explanation
of the centennial change of global mean annual mean SAT. Apparently, in the case
of long-term climatic variability the stochastic forcing can be considered as a zero
hypothesis.
A consideration of the impact of low-frequency climatic fluctuations on the level

of the Caspian Sea has shown that the long-term variability of the level is connected

fl

c Ocean. It
turned out that positive SST anomalies correlate with enhanced precipitation in the
basin of the Volga watershed and vice versa. The main cause of variations of the
Caspian Sea level is the long-term dynamics of ENSO events, which should be
considered chaotic.
An important part of the discussed problem is the study of anthropogenic climate
change. Calculations have shown that a doubling of CO 2 concentration should
result in the outgoing longwave radiation at the level of tropopause decreasing by
3.1 W m − 2 and the downward longwave radiation flux in the stratosphere growing
by about 1.3 W m − 2 . Thus the total RF at the tropospheric top level will constitute
4.4 W m − 2 . Calculations of the resulting SAT change with the use of 11 climate
models revealed a warming within 2.1

first of all with SST anomalies in the eastern sector of the tropical Paci

4.8 ° C, as well as intensi cation of global

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mean precipitation within 1 10 %.

According to Bengtsson (1999), before 1980, the centennial change of the global
mean SAT was characterized by the prevailing contribution of natural variability
with the subsequent increase of the anthropogenic contribution. An important task
of subsequent developments is to improve the numerical modeling (

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(first of all, from
the viewpoint of a more adequate consideration of various mechanisms of feed-
backs) in order to provide reliable forecasts on regional and local scales. Quite an
urgent problem of global modeling consists in the interactive consideration of
biogeochemical cycles.
One of the most important aspects of numerical climate modeling is an
assessment of the contribution of anthropogenic climate-forming factors. In this
connection, Allen et al. (1999) discussed the possibilities of recognition, evaluation,
and forecast of the contribution of anthropogenic global climate change, charac-
terized by the SAT, with regard for available data of observations and numerical
modeling. The latter is carried out bearing in mind the internal variability of the
climate system, as well as the impact of the greenhouse effect (and respective
climate warming) and sulphate aerosol (the effect of climate cooling).
The four global 3D models of interactive atmosphere-ocean system predicted
an increase of the global mean SAT for the decade 2036

- 2046 (compared to

pre-industrial level) within 1.1 2.3 K. Calculations of the climate system sensitivity

to a doubled CO 2 concentration gave values within 2.5

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3.5 K. According to

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