Introduction - Climate Change: Identification and Projections - page 6

an effect. However, statistical analysis is clear: the sun can explain both
large and small climatic variations, which can be observed despite the
natural variability of the climate. This analysis relies on climatic databases
which are, as a whole, accepted by the IPCC (AR5, Chapter 5).
Beyond statistical analysis, the predictive power of the models identified
helps to confirm their validity. Solely on the basis of informations known in
2000, our models were able to provide a remarkably accurate reproduction
of the “climatic pause” which occurred shortly after and which is continuing
even now. It is not so with IPCC models: global temperatures observed
systematically fall below the lower end of the range of short-term projections
produced by these models, even when updated in 2006.
Regarding long-term predictions, they are highly dependent on the future
of solar activity, and the author does not have the expertise necessary to
assess the projections made by solar physics specialists. He is also unable to
confirm or contradict the hypotheses on the forms of greenhouse effect, and
the climate sensitivity coefficient which results from them. With the models
identified, there is a wide range of extrapolations from the climate of the past
millennium whereby, in the worst case scenario, a warming of two degrees
compared to pre-industrial temperatures is unlikely to be reached by the end
of the 21 st Century, and the current climatic pause may be but an indication
of a return to the little ice age of the 17 th and 18 th Centuries.
1.4. Contents of the work
The goal of this work is to describe our methodological approach with
enough accuracy so that the reader, equipped with some knowledge on the
theory of systems, in modeling and simulation 7 , can initially verify its
validity, and if necessary, reproduce and use them. Only Chapters 4 and 6
pose any problems to such a reader. Nevertheless, they are within reach of
any Bachelor's degree-level student of physics and mathematics. The reader
with a basic scientific background may benefit from a quick overview.
Chapter 2 presents the climatic variables and data. The large institutes
and organizations (NOAA, GISS, CRU) make climatic data available.
“Historic” temperatures overlap neatly from 1850 or 1880, eras when
7 Of course, it is important to have the necessary software, such as Matlab ® or similar.