Whilst a lot of attention has been given to changing
temperatures, changes in precipitation are also
important. Models of the climate are used to estimate
future changes in precipitation.
Simulation of 20th century precipitation
Climate
models are used to calculate what changes in climate will
occur due to natural and artificial “forcing”. The models
are often referred to by the letters GCM (Global/General
Circulation/Climate Models) or AOGCM (Atmosphere-Ocean
coupled GCM). Confidence in the conclusions of the models
depends, in part, on how well they have simulated changes
in the past.
IPCC Technical Assessment Report -
Precipitation
The IPCC Technical Assessment Report 4
(TAR4) presents a graph showing the average results of
precipitation simulations using 8 models. The graph is
for global mean precipitation adjusted so that the
average for the period 1961 to 1990 is zero. It covers
the period 1940 to 1998. This graph is reproduced
below.
