Geoscience Reference
In-Depth Information
HadCM2-G5 climate model developed at the Hadley Centre (Great Britain), the
global mean
“
greenhouse
”
warming in the period 1996
2004 should constitute
-
1.35 K, and the
“
sulphate
”
cooling will constitute 0.35 K, and thus the resulting
warming will reach 1 K.
With the anthropogenic SAT increase in the 20th century equal to 0.25
0.5 K
per 100 years, the calculations made with a simple climate model, predict the 1
-
2K
uncertainty of the balanced SAT forecast by the year 2040. Such estimates can,
however, be suf
-
ciently reliable only with an adequate consideration of the char-
acteristic time of the ocean
s adaptation. A critically important aspect of prognostic
estimates is a necessity to take into account possible sudden non-linear climate
changes, which seriously limits the lead time of forecasts.
The most attractive perspective for assessment and forecast of anthropogenic
SAT changes is connected with analysis of the spatial-temporal variability of the
SAT
'
fields that takes into account the impacts of the greenhouse effect and aerosol.
Realization of this approach is seriously complicated, however, by impossibility of
reliable prescription of aerosol forcing on the SAT
field. A serious problem is also a
necessity to take into account the climatic impact of changes in the content of
stratospheric and tropospheric ozone.
5.4.5 Contradictoriness of the Climate Study Results
The problem of anthropogenic global warming is now in the centre of attention of
not only specialists but also wide circles of population. With a deeper under-
standing of this problem, there appears a feeling of inconsistency of the results
obtained in this
field, especially during the last decade. In this connection, Mahlman
(1998) carried out an overview of such results aimed at analyzing of the funda-
mental scienti
c aspects of the problem under discussion, in which the emphasis is
placed on the role of numerical modeling and analysis of observational data in
understanding of the present climate change. The monograph by Weber (1992) has
been dedicated to the same theme.
The main dif
culty in understanding the causes of climate change is connected
with a still preserved impossibility of an adequate consideration of climatic feed-
backs. First of all, this refers to the cloud-radiation feedback, direct and indirect
(through the impact on radiative properties of clouds) climatic impact of atmo-
spheric aerosol as well as the impact of the atmosphere-ocean interaction on climate
formation.
The often ignored speci
c manifestation of the
“
greenhouse
”
climate warming is
the system
of deep layers of the ocean spans
centuries and even thousands of years). Schlesinger et al. (2000) pointed out,
for instance, the existence of the global SAT oscillations with a period of about
65
'
s large inertia (the thermal
“
memory
”
1992. It is important
that principal differences between numerical modeling (and forecasts) of weather
and climate should be taken into account. In the case of numerical climate
-
70 years from the observational data for the period 1858
-
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