Emissions scenarios

Scenarios have been developed describing alternative pathways of greenhouse gas emissions up to 2100, which depend on assumptions about future global socio-economic and demographic developments. Six different emissions scenarios are presented, taken from the IPCC Special Report on Emissions Scenarios (SRES).

The Special Report on Emissions Scenarios (SRES) describes possible future developments of the world grouped in scenario families that each follow a storyline. Each storyline assumes a distinctly different direction for future developments, such that the four storylines differ in increasingly irreversible ways.

The four scenario families, named “A1”, “A2”, “B1” and “B2”, cover a wide range of key “future” characteristics such as demographic change, economic development, and technological change. Each storyline is quantified in a number of different scenarios (40 in total. Six of these are highlighted by the SRES report to illustrate alternative conditions, three for the A1 storyline and one each for the other storylines. The scenarios were used as input data for the FINSKEN scenarios.

The storylines can be described briefly as follows:

•  A1 storyline and scenario family: a future world of very rapid economic growth, global population that peaks in midcentury and declines thereafter, and rapid introduction of new and more efficient technologies. Three groups are distinguished within the A1 scenario family according to their technological emphasis: fossil intensive (A1FI), non-fossil energy sources (A1T), or a balance across all sources (A1B).
• A2 storyline and scenario family: a very heterogeneous world with continuously increasing global population and regionally oriented economic growth that is more fragmented.
• B1 storyline and scenario family: 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.
•  B2 storyline and scenario family: a world in which the emphasis is on local solutions to economic, social, and environmental sustainability, with continuously increasing population (lower than A2) and intermediate economic development.

For more details about the storylines see the Main Characteristics of the Four SRES Storylines and Scenario Families which is Box SPM-1 of the Special Report on Emission Scenarios

For access to SRES data covering large world regions see the SRES home-page