INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE WMO UNEP ______________________________________________________________________________________________________________________ _ INTERGOVERNMENTAL PANEL IPCC -XXI/INF. 1 ON CLIMATE CHANGE (22.IX.2003) TWENTY-FIRST SESSION Agenda item: 8 Vienna, 3 and 6-7 November 2003 ENGLISH ONLY IPCC MEETING ON CURRENT SCIENTIFIC UNDERSTANDING OF THE PROCESSES AFFECTING TERRESTRIAL CARBON STOCKS AND HUMAN INFLUENCES UPON THEM Geneva, Switzerland, 21 –23 July 2003 Expert Meeting Report _______________________________________________________________________________________________________________________ IPCC Secretariat, c/o WMO, 7bis, Avenue de la Paix, C.P. N° 2300, 1211 Geneva 2, SWITZERLAND Phone: +41 22 730 8208/8254 Fax: +41 22 730 8025/8013 E-mail: [email protected] Website: http://www.ipcc.ch INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE IPCC Meeting on Current Scientific Understanding of the Processes Affecting Terrestrial Carbon Stocks and Human Influences upon Them Geneva, Switzerland 21–23 July 2003 Expert Meeting Report Supporting material prepared for consideration by the Intergovernmetal Panel on Climate Change. This supporting material has not been subject to formal IPCC review and approval process. IPCC Meeting on Current Scientific Understanding of the Processes Affecting Terrestrial Carbon Stocks and Human Influences upon Them Editors: David Schimel and Martin Manning IPCC Working Group I Technical Support Unit National Oceanic & Atmospheric Administration (NOAA) DSRC R/AL/8 Room 3A212 325 Broadway Boulder, CO 80305 USA Email: [email protected] http://ipcc-wg1.ucar.edu/ September 2003 Acknowledgements The Management Committee is very grateful for the hard work of the Program Committee (see below) who worked within tight deadlines to secure the participation of 32 leading experts on the terrestrial carbon cycle from 19 countries. We are also very grateful to the experts who attended the meeting for their careful preparations and the quality of their presentations, and for their commitment in preparing a detailed summary of the meeting within a few weeks. We would also like to acknowledge the support of the IPCC Secretariat, in Geneva, who hosted the meeting, and the IPCC Working Group I Technical Support Unit, in Boulder, Colorado. IPCC Management Committee Susan Solomon (co-chair), Martin Parry (co-chair), Ogunlade Davidson, Thelma Krug, Rajendra Pachauri, Geoff Love (IPCC Secretariat) Program Committee Daniel Murdiyarso (co-chair), David Schimel (co-chair), Mike Apps, Josep Canadell, Martin Heimann, Victor Jaramillo. i Foreword The Intergovernmental Panel on Climate Change (IPCC) was established by the United Nations Environment Program (UNEP) and the World Meteorological Organization (WMO) in 1988 to undertake scientific and technical assessments relating to climate change. In the Marrakech Accords decision (11/CP.7, paragraph 3) on Land Use, Land-Use Change and Forestry (LULUCF) the Conference of Parties to the UNFCCC invited the IPCC “To develop practicable methodologies to factor out direct human-induced changes in carbon stocks and greenhouse gas emissions by sources and removals by sinks from changes in carbon stocks and greenhouse gas emissions by sources and removals by sinks due to indirect human-induced and natural effects (such as those from carbon dioxide fertilization and nitrogen deposition), and effects due to past practices in forests (pre- reference year), to be submitted to the Conference of the Parties at its tenth session;”. In consideration of a response to this invitation, the 28th Session of the IPCC Bureau (Geneva, 10–11 December 2002) noted that a number of critical scientific questions needed to be addressed and that many key scientific issues were considered speculative at the time of LULUCF (2000) and the WG1 and WG2 TARs. In view of this it was considered essential that the IPCC survey the current state of the science, and, in particular, the developments in the science since these reports. Subsequently, the 20th Session of the Panel agreed to a proposal by the Chair that the IPCC would conduct a high level scientific meeting. The meeting would survey the current scientific understanding of the processes affecting terrestrial carbon stocks and human influences upon them. The IPCC Bureau would then make recommendations for further actions on this topic, to be available for consideration by the 21st Session of the Panel (October 2003). On behalf of the Management Committee we are pleased to present the following report of that scientific meeting, held in Geneva from 21 to 23 July, 2003. We would like to commend the Program Committee and all the participants for the timely manner in which they prepared material for the scientific meeting and completed the comprehensive science statement, which forms the bulk of this report. We recommend that this report be made available to the Subsidiary Body for Scientific and Technological Advice (SBSTA), and other interested parties, as a contribution to understanding the scientific and technical issues relevant to the issue of factoring out. Susan Solomon Martin Parry Co-Chairs IPCC Management Committee iii Table of Contents Acknowledgements................................................................................................................. i Foreword.................................................................................................................................iii Table of Contents....................................................................................................................v Science Statement..................................................................................................................1 Key Conclusions and Recommendations.........................................................................2 1. Introduction..................................................................................................................5 2. Workshop Conclusions Regarding Previous Relevant IPCC Assessments.............8 3. Separability..................................................................................................................8 4. Permanence ..............................................................................................................10 5. Saturation ..................................................................................................................11 6. Stability ......................................................................................................................12 7. Attribution...................................................................................................................14 8. Synthesis – Time Scales...........................................................................................15 9. Synthesis – Space Scales ........................................................................................16 10. Research Needs........................................................................................................17 Glossary and Acronyms...................................................................................................19 Appendix 1: Program Organizing Committee...................................................................21 Appendix 2: Charge to the Meeting ...................................................................................22 Appendix 3: Workshop Program........................................................................................24 Appendix 4: Workshop Participants..................................................................................27 v IPCC Meeting on Terrestrial Carbon Stocks Science Statement on Current Scientific Understanding of the Processes Affecting Terrestrial Carbon Stocks and Human Influences upon Them Expert Contributors M. Apps, P. Artaxo, D. Barrett, J. Canadell, A. Cescatti, G. Churkina, P. Ciais, E. Cienciala, P. Cox, C. Field, M. Heimann, E. Holland, R. Houghton, V. Jaramillo, F. Joos, M. Kanninen, J.B. Kauffman, W. Kurz, R.D. Lasco, B. Law, Y. Malhi, R. McMurtrie, Y. Morikawa, D. Murdiyarso, S. Nilsson, W. Ogana, P. Peylin, O. Sala, D. Schimel, P. Smith, G. Zhou, S. Zimov Editors M. Apps, J. Canadell, M. Heimann, V. Jaramillo, D. Murdiyarso, D. Schimel, (Meeting Program Committee) and M. Manning (IPCC Working Group I TSU) Science Statement 1 IPCC Meeting on Terrestrial Carbon Stocks Key Conclusions and Recommendations The scientific community cannot currently provide a practicable methodology that would factor out direct human-induced effects from indirect human-induced and natural effects for any broad range of LULUCF activities and circumstances. Research efforts are addressing some particular effects, such as CO2 fertilization, over a range of spatial scales and are providing information relevant to the separability and attribution of different effects at specific sites where good historical information is available and intensive measurements are being carried out. Such efforts are expected to provide an increasing understanding of the feasibility and practicability of a broadly based approach to the issues of separability and attribution. In many circumstances the direct effects of ARD activities on carbon stocks and greenhouse gas emissions and removals will be much larger than the sum of indirect human-induced and natural effects, and the non-linear interactions among all effects. The scientific and technical community can provide guidance that will evolve and improve