How Do Scientists Estimate the Climate of the Future and How Reliable are Their Projections?
• Projections of future changes in climate are typically based on three sources of information: – Knowledge of historical climate variability and change – Scientific understanding of the climate system – Computer models of the climate system that generate projections of future climate based upon a number of variables • Of these three, climate models have received considerable attention. A number of different models exist and each represents the climate in a different way, resulting in large differences among models in projections of future climate change. • A number of current models do a reasonable job of simulating past climate variability (decades to centuries), but all such models perform poorly at modeling short-term climate variability (days-years) and regional climate variability. • The projections of climate models are also highly dependent upon the assumptions used regarding future trends in greenhouse gas emissions and atmospheric concentrations.
