Forecasts of Future Temperature Change
In an effort to understand the complexities
of the earths climate, scientists run computer simulations.
In these simulations, equations represent the physical
processes of the climatesuch as seasonal changes in
sunlight, evaporation and condensation of water, warming of
the atmosphere by ocean waters, and so on.
Every simulation begins with assumptions.
In generating the forecasts shown on this graph, researchers
assumed that there would be no action to restrict future greenhouse
gas emissions. But each line represents a different set of
assumptions regarding future economic development and fundamental
climate processes. These different assumptions generate very
different future possibilities.
The researchers who created this graph
explain that two-thirds of the overall difference between
the extreme forecasts is due to uncertainty related to basic
climate processes, such as the influence of clouds and ocean
circulation. The rest of the difference reflects uncertainty
in future emissions of carbon dioxide, which depend on population
growth, economic growth, and technological changes.