5.9. Carter

Keynote Presentations from the 2nd ALTER-Net Summer School, Peyresq 1 - 13 September 2007

Abstract

Scenarios of global change

The past centuries have witnessed a rapid increase in human population as a result of economic development and the successful exploitation of natural resources. Human activities have affected the environment through pollution and degradation of the basic "commons": air, water and soil. This has led to environmental problems such as acid rain, climate change, stratospheric ozone depletion and soil erosion. These changes are termed "global changes", because they affect all areas of the globe and because they touch upon all aspects of the relationship between human development and environmental change.

Europe has also experienced widespread global changes, a large portion of which are anthropogenic in origin. In order to anticipate global changes during the coming decades, and to prepare for their likely impacts on ecosystems and society, it is necessary to project current trends into the future. However, there are large uncertainties associated with estimates of human influence on complex natural systems, and it is impossible to predict the future with any confidence. Instead, it is customary to construct "scenarios". A scenario can be defined as "a coherent, internally consistent and plausible description of a possible future state of the world" (IPCC, 1994).

This lecture will introduce students to the concept of scenarios, contrasting descriptive and normative scenarios, emphasising the role of the base case scenario, and illustrating alternative approaches to scenario development:

• Qualitative scenarios
• Incremental scenarios for sensitivity testing
• Analogue scenarios
• Model-based scenarios
• Scenarios based on expert judgement
• Composite scenarios

Global change scenarios are often selected to shed light on key uncertainties in projections, though some studies may adopt other selection criteria (e.g. choosing the "best estimate" or "worst case" scenario). Scenarios can cover a wide range of issues, including:

• Socio-economic factors
• Land use and land cover
• Atmospheric composition
• Water quality
• Climate
• Sea level

Examples of each of these scenario types will be presented and students will be encouraged to participate in a scenario building exercise of their own as part of the group work following the lecture.

Recommended background literature on this presentation:

• Alcamo J (2001) Scenarios as tools for international environmental assessments. Environmental issue report No 24, Experts' corner report Prospects and Scenarios No 5, European Environment Agency (pdf: 400KB), Luxembourg, pp 31.
  
• Carpenter SR, Pingali PL, Bennett EM, Zurek MB (Eds.) (2005) Ecosystems and human well-being: Scenarios. Findings of the Scenarios Working Group, Volume 2, Millennium Ecosystem Assessment, Island Press, especially Chapters 2 (Raskin et al.), 6 (Alcamo et al.), 7 (Nelson et al.) and 9 (Alcamo et al.). http://www.millenniumassessment.org/en/Scenarios.aspx
• Carter TR, La Rovere EL, Jones RN, Leemans R, Mearns LO, Nakicenovic N, Pittock AB, Semenov SM, Skea J (2001) Developing and applying scenarios. In: McCarthy JJ, et al. (eds), Climate change (2001) Impacts, adaptation, and vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge and New York, pp 145-190. http://www.grida.no/climate/ipcc_tar/
• Carter TR, Jones RN, Lu X, Bhadwal S, Conde C, Mearns LO, O’Neill BC, Rounsevell MDA, Zurek MB (2007) New assessment methods and the characterisation of future conditions. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Parry ML, Canziani OF, Palutikof JP, van der Linden PJ, Hanson CE (Eds.) Cambridge University Press, Cambridge, UK, 133-171. http://www.gtp89.dial.pipex.com/02.pdf
• Grübler A, Nakicenovic N (2001) Identifying dangers in an uncertain climate. Nature, 412, 15. doi: 10.1038/35083752
• Lebel L, Thongbai P, Kok K, Agard JBR, Bennett E, Biggs R, Ferreira M, Filer C, Gokhale Y, Mala W, Rumsey C, Velarde SJ, Zurek M (2005) Sub-global scenarios. In: Ecosystems and Human Well-being: Multiscale Assessments, Volume 4, Millennium Ecosystem Assessment, Carpenter SR, Pingali PL, Bennett EM, Zurek MB (Eds) Island Press, 229-259. Chapter 10: http://www.maweb.org/documents/document.348.aspx.pdf.
• MNP (2006) Integrated modelling of global environmental change. An overview of IMAGE 2.4. (Bouwman AF, Kram T, Klein Goldewijk K (Eds) Netherlands Environmental Assessment Agency (MNP), Bilthoven, The Netherlands, 228 pp. http://www.mnp.nl/en/publications/2006/Integratedmodellingofglobalenvironmentalchange.AnoverviewofIMAGE2.4.html
• Nakicenovic N, Alcamo J, Davis G, de Vries B, Fenhann J, Gaffin S, Gregory K, Grübler A, Jung TY, Kram T, La Rovere EL, Michaelis L, Mori S, Morita T, Pepper W, Pitcher H, Price L, Raihi K, Roehrl A, Rogner H-H, Sankovski A, Schlesinger M, Shukla P, Smith S, Swart R, van Rooijen S, Victor N, Dadi Z (2000) Emissions scenarios. A Special Report of Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press, 599 pp. http://www.grida.no/climate/ipcc/emission/index.htm
• Parry ML (2002) Scenarios for climate impact and adaptation assessment. Global Environmental Change 12: 149-153. doi:10.1016/S0959-3780(02)00038-9
• Schneider SH (2001) What is 'dangerous' climate change? Nature, 411, 17-19. doi: 10.1038/35075167
• Schröter D, Cramer W, Leemans R, Prentice IC, Araújo MB, Arnell NW, Bondeau A, Bugmann H, Carter TR, Garcia CA, de la Vega-Leinert AC, Erhard M, Ewert F, Glendining M, House JI, Kankaanpää S, Klein RJT, Lavorel S, Lindner M, Metzger MJ, Meyer J, Mitchell TD, Reginster I, Rounsevell M, Sabaté S, Sitch S, Smith B, Smith J, Smith P, Sykes MT, Thonicke K, Thuiller W, Tuck G, Zaehle S, Zierl B (2005) Ecosystem service supply and vulnerability to global change in Europe. Science 310:1333-1337, doi:10.1126/science.1115233