Emissions Scenarios

A scenario is defined as a “... coherent, internally consistent, and plausible description of a possible future state of the world” (IPCC, 1994).

Scientists use global climate models (GCMs) to illustrate possible future climates. These are complex three-dimensional mathematical models that model atmospheric, oceanic, and other bio-physical processes. GCMs differ in their results partly based on different possible future greenhouse gas emissions levels. Running a range of scenarios gives a good idea of the range of possible future climate. Some commonly used emissions scenarios are described below:

Emissions Scenario Description


A future world of very rapid economic growth and intensive use of fossil fuels


A future world of very rapid economic growth, and rapid introduction of new and more efficient technology


A future world of very rapid economic growth, and a mix of technological developments and fossil fuel use


A future world of ‘business as usual' with moderate economic growth, more heterogeneously distributed and with a higher population growth rate than in A1


A convergent world with rapid change in economic structures, ‘dematerialisation’, introduction of clean technologies, and the lowest rate of population growth


A world in which the emphasis is on local solutions to economic, social and environmental sustainability, intermediate levels of economic development and a lower population growth rate than A2

Saskatchewan climate change scenarios used elsewhere in this site employed a range of emissions scenarios in order to illustrate the range of possible climate future for the province.

For further discussion of emissions scenarios and global climate models see the Climate Scenarios Primer by the Canadian Institute for Climate Studies or, for a more detailed discussion related to Saskatchewan, see the Climate Scenarios for Saskatchewan report.


  1. Canadian Institute for Climate Studies (2000): Climate Scenarios Primer - A non-technical introduction to climate scenarios and the science behind projections of the future climate.
  2. Elaine Barrow, 2009: Climate Scenarios for Saskatchewan
  3. IPCC (1994): Technical Guidelines for Assessing Climate Change Impacts and Adaptations. Prepared by Working Group II [Carter, T.R., Parry, M.L., Harasawa, H. and Nishioka, S. (Eds.)] and WMO/UNEP. CGER-IO15-94. University College, London, U.K. and Centre for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Japan, 59pp.