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We cannot anticipate everything, but we try to assemble as many of the pieces as possible in order
to predict the future. The science – or the art – of building scenarios requires a degree of control
over a wide range of factors, all intricately linked. It is like a game, where we have to guess how
changing one thing will affect the whole. Some elements appear simple – it is easy to imagine that
rising atmospheric temperatures will melt the sea ice and cause sea level to rise, perhaps threaten-
ing coastal populations – but at what speed and what intensity and will this start a chain reaction
of new calamities?
Back to the future: The science of
building scenarios
CLIMATE PREDICTIONS
6
MORE
MARKET-ORIENTED
D R I V I N G F O R C E S
MORE
ENVIRONMENTAL
MORE
GLOBAL
MORE
REGIONAL
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The A1 scenario
describes a future world of
very rapid economic growth, a global popula-
tion that peaks in mid-century and declines
thereafter, and the rapid introduction of new
and more efficient technologies. Specific re-
gional patterns tend to disappear as a result
of increased cultural and social interaction.
The gap between regions, regarding per
capita income, reduces substantially. This
scenario develops into three groups that de-
scribe alternative in the development of en-
ergy supply: fossil intensive (A1FI), non-fos-
sil energy sources (A1T), or a balance (A1B)
across all sources.
The A2 scenario
describes a very heteroge-
neous world, based on the continued sepa-
ration and preservation of local identities.
Fertility patterns across regions converge
very slowly, which results in a continuously
increasing population. Economic develop-
ment is regionally oriented and per capita
economic growth and technological change
more fragmented and slower than in the A1
scenario.
The B1 scenario
describes a convergent
world with a population that peaks in mid-
century and declines thereafter (as in the A1
scenario), but with a rapid change in eco-
nomic structures towards a service and infor-
mation economy, with reductions in material
intensity and the introduction of clean and
resource efficient technologies. The empha-
sis is on global solutions to economic, social
and environmental sustainability, including
improved equity, but without additional cli-
mate initiatives.
The B2 scenario
describes a world in which
the emphasis is on local solutions to eco-
nomic, social, and environmental sustainabil-
ity rather than the global approach in B1. It is
a world with a continuously increasing global
population, but at a slower rate than other
scenarios, intermediate levels of economic
development, and slow but diverse techno-
logical change. Society is oriented towards
environmental protection and social equity,
and focuses on the local and regional level.