Transcript Common metrics (presentation by Mr. Stocker)

INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)
8th Session of AWG-KP: Technical Briefing, June 2, 2009
Science of Alternative Metrics
Thomas Stocker
Co-Chair IPCC WGI
Physics Institute
University of Bern
Switzerland
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)
IPCC Expert Meeting on the Science of Alternative Metrics
From the UNFCCC request to the product:
 Sep 08: Invitation by UNFCCC to IPCC to „undertake further technical
assessment of common alternative metrics“;
 Nov 08: IPCC Bureau selects a Scientific Steering Committee to hold an
Expert Meeting: T. Stocker (Chair), O. Davidson, T. Hiraishi,
R. Pichs-Madruga, S. Semenov;
 Jan 09: Response by IPCC informing UNFCCC that an Expert Meeting
will take place in Mar 09;
 Mar 09: Expert Meeting in Oslo: 35 international experts draft and
approve set of conclusions;
 Apr 09: 30th IPCC Plenary takes note of the Expert Meeting Report;
 6 May 09: Full Report of the Expert Meeting sent to UNFCCC .
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)
Cause-effect chain from emissions to climate change and damages
Uncertainty
Policy Relevance
(adapted from Fuglestvedt et al., 2003)
GWP
GTP
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)
Global Warming Potential
T
Global Warming Potential
GWPi (T ) 
 RFi ( t ) dt
0
T
 RFCO
0
2
( t ) dt
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)
Global Warming Potential
T
Global Warming Potential
GWPi (T ) 
 RFi ( t ) dt
0
T
 RFCO
2
( t ) dt
0
Global Temperature Potential
Ti ( t )
GTPi ( t ) 
TCO 2 ( t )
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)
IPCC Expert Meeting on the Science of Alternative Metrics
3 Sets of Key Conclusions:
 to UNFCCC
 to the Scientific Community
 to the Scoping of AR5
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)
IPCC Expert Meeting on the Science of Alternative Metrics
Key Conclusions to UNFCCC:

Global Warming Potential (GWP) is a well defined metric based on radiative forcing
that continues to be useful in a multi-gas approach. Shortcomings have been
identified; however the scientific basis has not been fully established to address these
shortcomings comprehensively in any currently discussed metric;

The effectiveness of the use of a given metric depends on the primary policy goal, for
example to limit the long term temperature change, limit rates of change, avoid
particular impacts, and balance costs and benefits. The GWP was not designed with a
particular policy goal in mind. Depending on the specific policy goal or goals,
alternative metrics may be preferable;

The GWP with the time horizon of 100 years is used in the Kyoto Protocol. The
numerical value of the GWP can depend markedly on the choice of time horizon. The
choice of any particular time horizon involves value judgments in terms of future
commitment to radiative forcing;

Timely information on potential future policy goals would facilitate research on
alternative metrics.
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)
IPCC Expert Meeting on the Science of Alternative Metrics
Key Conclusions to the Scientific Community:

Uncertainties
uncertainties associated with GTP, probability density functions for metrics
to encompass uncertainties associated with physical processes, quantify
indirect effects and interactions, mitigation costs;

New and Refined Areas or Metrics
Metrics for policy targets other than T, account for long-term, post-target,
post-horizon effects, comprehensive metrics including economics;

Relationships between Policy Frameworks and Metrics
impact of choice of alternative metrics on climate change outcomes and
costs, extension to short-lived pollutants.
INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
Working Group I
Co-Chairs: Thomas Stocker (Switzerland) and Qin Dahe (China)