# Presentation: 281705

## Current & Future IPCC Assesment of Emissions Scenarios

**Francisco C. de la Chesnaye**
- Climate Change Division
- U.S. Environmental Protection Agency
- U.S. Climate Change Science Program Workshop
- Session 2: Evaluating Assessments
- Washington, DC.  14 Nov 2005

## Outline

- Past IPCC efforts on scenarios
- Current Fourth Assessment Reports
- Recent consideration by IPCC on New Scenarios and possible directions
*Scenario: *“representation of key features of human and/or environmental systems in order to represent the evolution of the system under alternative assumptions, such as _population_, _economic growth_, _technological change_ and environmental sensitivity.”  *IPCC TAR, Chap 2.*

## Previous developed and used scenarios by IPCC

**INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC)**

- 1990

- 1992

- Six IS92 scenarios

- 1995

- Evaluation Scenarios

- 1996

- Panel decision
-  new scenarios

- 2000

- Special Report
- Emission Scenarios (SRES)

- 2001

- TAR

- 2004

- Start writing AR4

- ????

- Possible AR5

- SA90 scenarios

## Scenario Causal Chain

- Source: IPCC, TAR

## AR4 Physics Tests – CO2 Equivalents

- The relative effect of radiative forcing due to non-CO2 GHGs  and aerosols varies with scenario.

- Source:M. Manning, Laxenburg Workshop

**Notes:**
In the AR4, new climate change experiments with Atmosphere-Ocean General Circulation Models will be evaluated.  These include future climate change scenarios using SRES scenarios (A1B, B1 and A2) to  2100. 

## Global Population Projections

- Range Across Emissions Scenarios

- Source:Scenarios Database, NIES

## Gross World ProductRange Across Emissions Scenarios

- Source:Scenarios Database, NIES

## Carbon EmissionsRange Across Emissions Scenarios

- Source:Scenarios Database, NIES

## Expert Workshop on New Emission scenariosLaxenburg June 2005

**INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC)**

- Evaluate the future user needs and requirements of the various user communities and to assess to what extent current and past IPCC scenarios have fulfilled those needs.
- Identify what kind of scenarios could meet these user requirements (in light of the state of the art of scenario development and quantitative modeling of scenarios).
- Propose and evaluate options for the role of the IPCC in the development of new scenarios that would become available for research and assessment for the AR5.

## Possible Role of IPCC

** ****literature**

**‘****declare’**
**representative **
**scenarios**

**Development **
**of scenarios**

**Studies, **
**using scenarios**

**IPCC**

**IPCC**

- Guidance/ coordination

**Scenario/ **
**model groups**

**Other**
** ****research**
**groups**

**Policy user community**

- User requests

- Source: Laxenburg Workshop Report

## Decision at IPCC-24

- There is a need for new emissions scenarios, to be produced by the scientific community, with facilitation or coordination by the IPCC, to be available before a possible AR5.
- A Task Group be set up for the purpose of further defining:
- IPCC facilitation or coordination with the scientific community for development of scenarios.
- Deliverables of the emission scenarios development process, drawing on the user needs and scenario characteristics as outlined in the Laxenburg Workshop
- Process and timeline that should be followed for the development and use of the new emission scenarios.
- Organizational arrangements and a timetable for IPCC’s own activities.
- To consider the possibility of encouraging, but not itself facilitating, a wider family of non-climate scenarios within which emissions scenarios might sit.
- The Task Group will organize an Experts Meeting March 20-22 and then formulate a plan of work and present this to IPCC-25 for decision-making

## U.S Government View: Organize a process with the scientific community for developing new scenarios (driven by the modelers)

- International modeling community is now much larger and is attracting specialists from diverse fields
- ENSEMBLES (Europe)
- Project and the Innovation Modeling Comparison Project (Europe)
- Asian-Pacific Integrated Modeling consortia (NIES-Japan)
- Energy Modeling Forum (International)
- U.S. Climate Change Science Program
- Future assessment activities should engage the best people that the field has to offer as authors and reviewers of the state of the science.

## Follow the experience of AR4 where Lead Authors are now assessing the available literature published after SRES.
IPCC should not try to push the field in any pre-determined direction. 
Beyond assessment, IPCC could support the modeling community’s effort to develop new scenarios: 
Organize a Workshop or Meeting to (a) solicit input from various groups on their needs and useful approaches for scenario development; or (b) help foster communication between and coordination across user and developer groups 
Provide straightforward, non-prescriptive guidance and formats for researchers to facilitate  reporting of results and key assumptions to aid future assessments 

- IPCC should not try to push the field in any pre-determined direction.
- Beyond assessment, IPCC could support the modeling community’s effort to develop new scenarios:
- Organize a Workshop or Meeting to (a) solicit input from various groups on their needs and useful approaches for scenario development; or (b) help foster communication between and coordination across user and developer groups
- Provide straightforward, non-prescriptive guidance and formats for researchers to facilitate  reporting of results and key assumptions to aid future assessments

- U.S Government View (cont.):