Special Report on Emissions Scenarios

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The Special Report on Emissions Scenarios (SRES) was a report prepared by the Intergovernmental Panel on Climate Change (IPCC) for the Third Assessment Report, on future emission scenarios to be used for driving global circulation models to develop climate change scenarios. It was used to replace the IS92 scenarios used for the IPCC Second Assessment Report. The SRES Scenarios were also used for the Fourth Assessment Report.

The scenarios may be seen here.

1 Purpose
2 Scenario Families
- 2.1 A1
- 2.2 A2
- 2.3 B1
- 2.4 B2
3 SRES Scenarios and Climate Change Initiatives
- 3.1 References
4 External links

[edit] Purpose

Because projections of climate change depend heavily upon future human activity, climate models are run against scenarios. There are 40 different scenarios, each making different assumptions for future greenhouse gas pollution, land-use, etc. These scenarios are organized into families, which contain scenarios that are similar to each other in some respects. IPCC assessment report projections for the future are often made in the context of a specific scenario family.

[edit] Scenario Families

Scenario families contain individual scenarios with common themes. The six families of scenarios discussed in the IPCC's Third Assessment Report (TAR) and Fourth Assessment Report (AR4) are A1FI, A1B, A1T, A2, B1, and B2.

Scenario descriptions are based on those in AR4, which are identical to those in TAR. ^[1]

[edit] A1

The A1 scenarios are of a world more integrated. The A1 family of scenarios 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.

There are subsets to the A1 family based on their technological emphasis:

A1FI - an emphasis on fossil-fuels
A1B - A balanced emphasis on all energy sources.
A1T - Emphasis on non-fossil energy sources.

[edit] A2

The A2 scenarios are of a world more divided. The A2 family of scenarios 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 captia income.

[edit] B1

The B1 scenarios are of a world more integrated, and more ecologically friendly. The B1 scenarios are 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.

[edit] B2

The B2 scenarios are of a world more divided, but more ecologically friendly. The B2 scenarios are characterized by:

Continuously increasing population, but at a slower rate than in A2
Emphasis on local rather than global solutions to economic, social and environmental stability.
Intermediate levels of economic development.
Less rapid and more fragmented technological change than in B1 and A1.

[edit] SRES Scenarios and Climate Change Initiatives

While some scenarios assume a more environmentally friendly world than others, none include any climate-specific initiatives, such as the Kyoto Protocol.^[1]