The future ofclimate modelling 109A limitation of the regional modelling technique we have described
is that, although the global model provides the boundary inputs for the
RCM, the RCM provides no interaction back on to the global model. As
larger computers become available it will be possible to run global mod-
els at substantially increased resolution so that this limitation becomes
less serious; at the same time RCMs will acquire an ability to deal with
detail on even smaller scales. Some examples of regional model simu-
lations are given in Chapter 6 (Figure 6.10).
Another technique is that ofStatistical Downscalingthat has been
widely employed in weather forecasting. This uses statistical methods to
relate large scale climate variables (or ‘predictors’) to regional or local
variables. The predictors from a global circulation climate model can
be fed into the statistical model to estimate the corresponding regional
climate characteristics. The advantage of this technique is that it can
easily be applied. Itsdisadvantage from the point of view of simulating
climate change is that it is not possible to be sure how far the statistical
relations apply to a climate-changed situation.
The future of climate modelling
Very little has been said in this chapter about the biosphere. Chapter 3 re-
ferred to comparatively simple models of the carbon cycle which include
chemical and biological processes and simple non-interactive descrip-
tions of atmospheric processes and ocean transport. The large three-
dimensional global circulation climate models described in this chapter
contain a lot of dynamics and physics but no interactive chemistry or
biology. As the power of computers increases, global dynamical and
physical circulation models that couple in the biological and chemical
processes that make up the carbon cycle and the chemistry of other gases
are now being developed. Before very long we can expect that models
will be available that are fully interactive and comprehensive in their
inclusion of dynamical, physical, chemical and biological processes in
the atmosphere, the ocean and on the land.
Climate modelling continues to be a rapidly growing science. Al-
though useful attempts at simple climate models were made with early
computers it is only during the last ten years or so that computers have
been powerful enough for coupled atmosphere–ocean models to be em-
ployed for climate prediction and that their results have been sufficiently
comprehensive and credible for them to be taken seriously by policy
makers. The climate models which have been developed are probably
the most elaborate and sophisticated of computer models developed in
any area of natural science. Further, climate models that describe the
natural science of climate are now being coupled with socio-economic