Geoscience Reference
In-Depth Information
0.16
±
0.06
°
C/10 years. The statistically substantial trend of the difference between
the Earth
'
s surface and the lower troposphere constituted 0.13
±
0.06
°
C/10 years,
which differs from the data for the period 1958
1978, when the average global
temperature in the lower troposphere increased more rapidly (by 0.03
-
C/10 years)
than near the surface. The considerable differences between the temperature trends
in the lower troposphere and near the surface are most likely to be real. So far, these
differences cannot be convincingly explained. The climate warming in the Northern
Hemisphere observed in the 20th century was the most substantial over the last
1,000 years according to the observational warming (Mikolajewicz et al. 2004;
Islam et al. 2005; Jacobson 2000).
Special attention has been paid in the IPCC Reports (IPCC 2001, 2005, 2007) to
the possibility for predicting future climatic changes. The chaotic character of the
atmospheric dynamics limits the long-term weather forecasts to 1 or 2 weeks and
prevents the prediction of a detailed climate change (e.g., it is impossible to predict
precipitation in Great Britain for the winter of 2050). However, it is possible to
consider climate projections, that is, to develop scenarios of probable climate
changes, due to the continuing growth of GHGs concentrations in the atmosphere.
Such scenarios, if credible, may be useful for decision-makers in the
°
field of eco-
logical policy. The basic method to make such scenarios tangible involves the use
of numerical climate models Climate that simulate interactive processes in the
atmosphere-ocean-land surface-cryosphere-biosphere climatic system (J
nsson
et al. 2004). As Collins and Senior (2002) noted, because there are so many such
models, the serious difficulty arises as to which is the best model to choose. As this
problem of choice is insoluble, there remains the possibility of comparing the
climate scenarios obtained by using various models.
According to the IPCC recommendations, four levels of projection reliability are
considered:
ö
(1) from reliable to very probable (in this case there is an agreement between the
results for most of the models);
(2) very probably (an agreement of new projections obtained with the latest
models);
(3) probable (new projections with an agreement for a small number of models);
and
(4)
restrictedly probable (model results are not certain but changes are physically
possible).
culty in giving substance to the projections is the impossibility of
determining agreed predictions on how GHGs concentrations will evolve in future,
which makes it necessary to take into account a totality of various scenarios. The
huge thermal inertia of the World Ocean dictates a possibility of delayed climatic
impacts of the GHGs concentrations, which has already increased.
Calculations of annual average global SAT using the energy-balance climate
model with various scenarios of the temporal variations of CO 2 concentrations have
led to SAT intervals in 2020, 2050, and 2100 to be 0.3
A principal dif
0.9, 0.7
2.6, and 1.4
5.8
°
C
-
-
-
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