date: Wed, 26 Aug 1998 17:25:39 -0600 (MDT) from: Linda Mearns subject: Chap. 13 - Final I hope to: m.hulme@uea.ac.uk (Mike Hulme) Mike, Below is what I sent as our final chapter. I also included this little intro paragraph on things. I hope it is acceptable this time. By the way, any info from Schimel regarding the US Assessment climate models? Cheers, Linda Below is the new outline fo the chapter on climate change scenario development. In preparing the new (and it is hoped, final) chapter outline, we considered material prepared in other outlines for comparison. We examined other chapter outlines for TAR for WGI and II and find that the content of our outline is in keeping with the basic stucture and breadth of material covered in other chapters. There remains, however, the issue of the fact that THIS SUBJECT HAS NOT BEEN COVERED IN EARLIER ASSESSMENTS. In going over chapters in all three Working Groups from the second assessment and from the chapter outlines for TAR, it is very clear that the point of departure for `assessment' is meant research that has appeared since the last assessment, and thus was not covered in the earlier assessments. It is important to note that this point of departure does not exist for the topic of climate change scenario development. We note that this truly does blur the distinction between a `review' and an `assessment' in this case. For example, consider the problem climate modelers would have in constructing and writing the current chapter 9 in WGI, if the topic of climate models and climate model projections had not been covered in SAR and FAR. We hope that the co-chairs of WGI will recognize and give due consideration to the unique aspects of this chapter. It cannot conform completely to expectations developed in the context of other chapters that cover material already examined in earlier assessments. Another issue that must be considered in viewing this outline is the fact that where simple climate model results are to be primarily discussed has not been determined. If it is decided that this discussion should reside in chapter 13, then, our outline will have to be expanded and the length of the chapter increased. This simple model discussion may also affect the choice of an additional lead author. We already have a total of five lead authors for a rather short chapter. We feel this is probably sufficient if the main discussion of simple models resides elsewhere. Final Draft Revised 8/26/98 IPCC WGI Chapter 13 CLIMATE CHANGE SCENARIO DEVELOPMENT L. O. Mearns (USA) and M. Hulme (UK), convening lead authors; T. Carter (Finland), M. Lal (India), R. Leemans (Netherlands), confirmed lead authors; B. Pittock (or Roger Jones) (Australia), possible additional lead author, or a climate modeler (G. Boer or J. Mitchell?) Contributors: (suggested) P. Whetton (Australia), Demetrious Gyalistras (Switzerland), M. Semenov (UK), Namasova (Chech Republic), R. Katz (USA) D. Wilks (USA), T. Kittel (USA), J. Mitchell (UK), G. Boer (Canada), Rob Wilby (USA/UK?) OUTLINE 13.1 Introduction 13.1.1 Definition of climate change scenario - distinction between climate change projections and scenarios 13.1.2 Need for scenarios -- impacts needs driven - specifically what information is needed by impacts researchers 13.1.3 Background on scenario use in quantitative climate impacts (Estimated Length - 1 page) 13.2 Sources of information on climate change for scenario development (This will be an assessment of the adequacy of these various sources. Most of them are still used or have been recently used (past 5 years)). 13.2.1. Sensitivity analysis 13.2.2. Analogue approaches 13.2.2.1. Historical 13.2.2.2 Paeleoclimate 13.2.3. Equilibrium GCM integrations 13.2.4. Transient integrations 13.2.5. Simple models - from integrated assessment models (Estimated Length - 1 page) 13.3 Baseline Climatologies - assessment of the effect on scenario formation 13.3.1. Historical period - effect of its variability on scenario formed 13.3.2. Resolution in time and space - density of station network - adequacy for regional representation 13.3.3 Deltas versus ratios (i.e., taking differences perturbed minus control, versus taking ratio of perturbed to control) (Estimated Length - 1/2 page) 13.4 Incorporation of Spatial and Temporal Resolution 13.4.1. Spatial - need for varying spatial scales (levels of aggregation), depending upon impacts type -- downscaling -- specific needs for use in impacts assessment - issues of spatial correlation and intercorrelation of variables 13.4.1.1 Dynamical downscaling -- increasing GCM resolution, stretched grids, nested regional models 13.4.1.2. Empirical Statistical Downscaling Methods (Note: coordination with chapter 10 is necessary here). 13.4.2 Temporal Resolution (assessment of mean versus variance changes in scenarios) 13.4.2.1. Incorporation of mean changes - the traditional, most commonly used scenario formation method - assessment of adequacy for representing climate change - 13.4.2.2. High frequency variability and extremes - daily to interannual 13.4.2.3. Low frequency -- decadal to century (Estimated Length 2 pages) 13.6 Measures of Uncertainty 13.6.1. Use of multiple GCM results to provide ranges of climate change scenarios, and to show climate change response to range of emission scenarios 13.6.2. Signal to noise in changes in climate variables and scaling of A/O GCMS 13.6.3 Effect of control run variability 13.6.4. Annotation of scenarios - effect of control run errors - climate model validation for impacts purposes (Estimated Length - 2 pages) 13.7 Consistency Among Scenario Components -- (Will assess how successfully scenarios maintain internal consistency of individual components, and issues of inconsistencies arising from taking only certain variables from climate models, and calculating others offline.) 13.7.1 Consistency of Sea Level Rise, Climate, and Direct CO2 Effects 13.7.2 Relationship between off-line vegetation/hydrology impacts calculations and vegetation/hydrology models coupled interactively into climate models, (i.e., assessment of direct use of climate model output) (coordination with material in WGII). (Estimated Length - 2/3 page) TOTAL LENGTH - a little over 7 pages. COORDINATION ISSUES - UNRESOLVED ISSUES WG I - Chap 10 -- Regional Analysis - technical downscaling, weather generators, regional validation, regional models WG I - Chap 9 - Climate Model Projections -- Where will simple model results go (primarily)? Where will the scenario ranges come from -- simple models, AOGCMs, combination of both? WG II - Chap 3 - Scenarios - how much detail about climate change scenarios will be in here? What discussion of the TGCIA scenarios will be in here? WG II - ? - Vegetation/hydrology models incorporated in GCMs WG III - Chap on emissions scenarios - relates to our uncertainty section Coordination with following individuals related to above issues: N. Nakicenovic, J. Mitchell, T. Carter, M. Hulme, L. Mearns, R. Leemans, F. Giorgi, H. Von Storch. END -- ****************************************************************************** Dr. Linda O. Mearns Phone: 303 497 8124 Scientist Fax: 303 497 8125 Environmental and Societal Impacts Group e-mail: lindam@ucar.edu NCAR P.O. Box 3000 Boulder, CO 80307