Models and Scenarios
- desk-based
- hours-weeks timescale
- low resource requirement.
Models are fundamental to decision making. They “enable us to specify our thinking on how [a] system responds to management” (Vesk & Rumpff 2018). At their core, models are simplified images or descriptions of relationships between things. Such pictures are profoundly powerful in shaping the way we think, express, and act.
Models often also include scenarios, plausible futures for indirect or direct drivers or policy interventions targeting these drivers. The consequences of scenarios on a system or parts/subsets of systems (e.g. global temperature, biodiversity, energy) are evaluated using models.
- Should I use an Models and Scenarios?
Models can be developed for a single issue (e.g. “should I buy bananas or apples”) or for an entire complex system (e.g. integrated assessment models, climate models), be applicable at one locality or across the globe, and be assessing current, past or future patterns and trends. At one end, models can take the form of “mental models” that guide decisions (also known as intuition). As mental models are undocumented, the underpinning logic cannot be readily communicated, transferred, assessed for completeness or validated against real world data. On the other end, mathematical equations can be used to describe complex systems, such as relationships between conservation and sustainable use of biodiversity and ecosystem services, human well-being and sustainable development (Diaz et al. 2015). Such quantitative models tend to be written down in equations or software code with explicit assumptions and variables; the encoded relationships and model outputs can be validated against past or current observations.
The combination of models and scenarios is a powerful tool to evaluate impacts of decisions on systems or their components. For example, scenarios on how to feed the growing human population can be used within land use models to assess future agricultural land needs, within biodiversity models to assess the impacts on species, within climate models to assess future emissions, etc.
- How do I use Models and Scenarios?
Mental models have been around since humans began to think.
Global system models/integrated assessment models were initially developed for acid rain modelling and have been used extensively to construct emissions scenarios for use in climate change assessments. Models are used routinely to forecast global climate change (e.g. IPCC 2013) and have been extended from climate models to Earth system models, that are calibrated and validated against historic climate data and future scenarios are compared across different models.
Methods vary from mental models, conceptual frameworks to mathematical qualitative models. Some models consist of a single component, others consist of interlinked and interacting models for multiple subsystems (e.g. vegetation, agriculture, climate, ocean, economics).
Depending on which model one wants to focus on, different references will be most appropriate.
- Examples of Models and Scenarios in Sustainability Research
Diaz S et al. (2015) The IPBES Conceptual Framework — connecting nature and people. Current Opinion in Environmental Sustainability 14: 1-16.
IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.
- References and Resources
Vesk P & Rumpff L (2018) Building models for better decisions. Decision Point Online, 5 October 2018 http://decision-point.com.au/article/building-models-for-better-decisions/
Diaz S et al. (2015) The IPBES Conceptual Framework — connecting nature and people. Current Opinion in Environmental Sustainability 14: 1-16.
IPBES (2016) The methodological assessment report on scenarios and models of biodiversity and ecosystem services. S. Ferrier, K. N. Ninan, P. Leadley, R. Alkemade, L. A. Acosta, H. R. Akçakaya, L. Brotons, W. W. L. Cheung, V. Christensen, K. A. Harhash, J. Kabubo-Mariara, C. Lundquist, M. Obersteiner, H. M. Pereira, G. Peterson, R. Pichs-Madruga, N. Ravindranath, C. Rondinini and B. A. Wintle (eds.). Secretariat of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Bonn, Germany. 348 pages.
Harfoot M, Tittensor DP, Newbold T, McInerny G, Smith M & Scharlemann JPW (2014) Integrated assessment models for ecologists: the present and the future. Global Ecology and Biogeography 23: 124-143.
- SSRP projects using Models and Scenarios
Suggested citation: Scharlemann, J. (2019). Models & Scenarios [online] Sussex Sustainability Research Programme Research Methods for Sustainability Catalogue. Available at: http://www.sussex.ac.uk/ssrp/resources/research-methods/models-scenarios.