IPCC AR4 Annual Extremes Variable Descriptions

CO2 Scenarios

The A1B scenario is characterized by:

  • Rapid economic growth.
  • A global population that reaches 9 billion in 2050 and then gradually declines.
  • The quick spread of new and efficient technologies.
  • A convergent world - income and way of life converge between regions.
  • Extensive social and cultural interactions worldwide.
  • A balanced emphasis on all energy sources.

    The B1 scenario is characterized by:

  • Rapid economic growth as in A1, but with rapid changes towards a service and information economy.
  • Population rising to 9 billion in 2050 and then declining as in A1.
  • Reductions in material intensity and the introduction of clean and resource efficient technologies.
  • An emphasis on global solutions to economic, social and environmental stability.

    The A2 scenario is characterized by:

  • A world of independently operating, self-reliant nations.
  • Continuously increasing population.
  • Regionally oriented economic development.
  • Slower and more fragmented technological changes and improvements to per capita income.




    More information on the economic scenarios used in the IPCC AR4 can be found here

    This page is maintained by Jamie Scott