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

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