Climate scenarios: CNRM_A1B

IPCC scenario: A1B

Main assumptions

  • 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.


Nakićenović, N., Alcamo, J., Davis, G., de Vries, B., Fenhann, J., Gaffin, S., Gregory, K. and Grübler, A. (2000) Special Report on Emissions Scenarios, Working Group III, Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge.

Global model: CNRM-CM3


Gibelin, A.L. and Déqué, M. (2003) Anthropogenic climate change over the Mediterranean region simulated by a global variable resolution model. Clim. Dyn. 20, 327-339.

Salas-Mélia, D., Chauvin, F., Déqué, M., Douville, H., Gueremy, J.F., Marquet, P., Planton, S., Royer, J.F. and Tyteca, S. (2005) Description and validation of the CNRM-CM3 global coupled model. CNRM working note 103.

Regional model: RCA3


Samuelsson, P., Jones, C. G., Willén, U., Ullerstig, A., Gollvik, S., Hansson, U., Jansson, C., Kjellström, E., Nikulin, G. and Wyser, K. (2011) The Rossby Centre Regional Climate model RCA3: model description and performance. Tellus A, 63:4–23.

Pan-European characteristics

This projection is included in Kjellström et al. (2011) (nr. 1 in their Table 1). There, the estimated future Pan-European changes (from 1961-1990 to 2071-2100) were compared with five other A1B-projections in terms of winter temperature (Fig. 4), summer temperature (Fig. 7), winter precipitation (Fig. 8) and summer precipitation (Fig. 9).

Winter temperature

The temperature increase in CNRM-A1B is larger than the average of all six A1B-projections in the extreme north-east of the domain but smaller in eastern and central Europe and over the British isles.

Summer temperature

The temperature increase in CNRM-A1B is larger than the average of all six A1B-projectins in southern Europe but lower than the average over the North Atlantic.

Winter precipitation

The change in winter precipitation in CNRM-A1B is smaller than in the other A1B-projections. The British isles and Fennoscandia will receive ca. 20% more precipitation while changes in continental Europe are small or non-significant.

Summer precipitation

CNRM-A1B features small changes in precipitation in large areas of continental Europe during summer. The British isles, western France, western Spain and Portugal, as well as Greece and Turkey will, however, receive less precipitation in the future, according to this scenario.

Further, annual average temperature and annual precipitation changes in Scandinavia (from 1961-1990 to 2011-2040, 2041-2070 and 2071-2100) in all 16 projections were compared by Kjellström et al. (2011; their Fig. 10). Generally, increases in temperature and precipitation are linearly related, where a weak temperature increase corresponds to a weak precipitation increase, and vice versa. Below, “increase” corresponds to both temperature and precipitation; “small” means that the increase is among the smaller ones of all 16 projections considered, “medium” that the increase is among the middle ones, and “large” that the increase is among the larger ones, for the period considered.

As compared with all 16 projections considered, the increase in projection CNRM_A1B is:
2011-2040: small/medium
2041-2070: small (change in precipitation is the smallest of all 16 projections)
2071-2100: small (change in precipitation is the smallest of all 16 projections)


Kjellström, E., Nikulin, G., Hansson, U., Strandberg, G. and Ullerstig, A. (2011) 21st century changes in the European climate: uncertainties derived from an ensemble of regional climate model simulations. Tellus A, 63:24–40.