The A1 storyline and scenario family describes a future world of very rapid economic growth, 
global population that peaks in mid-century and declines thereafter, and rapid introduction of 
new and more efficient technologies. In this storyline the A1B emissions scenario is 
characterized by balanced across all evergy sources not relying too heavily on one particular 
energy source.

The A2 storyline and scenario family describes a very heterogeneous world with continuously 
increasing global population and regionally oriented economic growth that is more fragmented and 
slower than in other storylines. 

The B1 storyline and scenario family describes a convergent world with the same global 
population as in the A1 storyline but with rapid changes in economic structures toward a service 
and information economy, with reductions in material intensity, and the introduction of clean 
and resource-efficient technologies.

IPCC, 2001: climate change 2001: the scientific basis. Contribution of Working Group 1 to the Third Assessment Report of the Intergovernmental Panel on Climate Change, edited by J. T. Houghton, Y. Ding, D. J. Griggs, M. Noguer, P. J. van der Linden, X. Dai, K. Maskell and C. A. Johnson (eds). Cambridge University Press, Cambridge, UK, and New York, USA, 2001. No. of pages: 881. International Journal of Climatology, 22: 1144. doi: 10.1002/joc.763