R. Prinn et al., Integrated global system model for climate policy assessment: Feedbacks and sensitivity studies, CLIM CHANGE, 41(3-4), 1999, pp. 469-546
Alternative policies to address global climate change are being debated in
many nations and within the United Nations Framework Convention on Climate
Change. To help provide objective and comprehensive analyses in support of
this process, we have developed a model of the global climate system consis
ting of coupled sub-models of economic growth and associated emissions, nat
ural fluxes, atmospheric chemistry, climate, and natural terrestrial ecosys
tems. The framework of this Integrated Global System Model is described and
the results of sample runs and a sensitivity analysis are presented. This
multi-component model addresses most of the major anthropogenic and natural
processes involved in climate change and also is computationally efficient
. As such, it can be used effectively to study parametric and structural un
certainty and to analyze the costs and impacts of many policy alternatives.
Initial runs of the model have helped to define and quantify a number of fe
edbacks among the sub-models, and to elucidate the geographical variations
in several variables that are relevant to climate science and policy. The e
ffect of changes in climate and atmospheric carbon dioxide levels on the up
take of carbon and emissions of methane and nitrous oxide by land ecosystem
s is one potentially important feedback which has been identified. The sens
itivity analysis has enabled preliminary assessment of the effects of uncer
tainty in the economic, atmospheric chemistry, and climate sub-models as th
ey influence critical model results such as predictions of temperature, sea
level, rainfall, and ecosystem productivity. We conclude that uncertainty
regarding economic growth, technological change, deep oceanic circulation,
aerosol radiative forcing, and cloud processes are important influences on
these outputs.