Scenarios

Using Scenarios to Structure Uncertainties

Scenarios are a decision making tool that policy makers can use to model the range of possible consequences associated with particular actions or events. The European Environmental Agency explains that scenarios are “based on 'if-then' propositions” and are not intended to be used as predictions or forecasts. These stories can help decision makers explore assumptions; test hypotheses; and ultimately, develop robust strategies capable of managing the irreducible uncertainties of global environmental change. Although many types of scenarios exist (i.e., high resolution scenarios, global climate model scenarios, analogue scenarios ), Lawrence Wilkinson reports that scenario building typically involves the following components.

1. Identifying a decision
2. Describing the current state of affairs
3. Describing any changes that are likely to occur
4. Describing the future consequences of those changes

Please visit the links shown below for more on environmental scenarios:

• The European Environmental Agency’s scenario product PRELUDE http://www.eea.europa.eu/multimedia/interactive/prelude-scenarios/prelude

• United States Environmental Protection Agency’s Environmental Scenarios Project http://www.epa.gov/ocfo/futures/env_scen.htm

• Intergovernmental Panel on Climate Change http://www.ipcc-data.org/

• Canadian Climate Change Scenario Network http://www.ccsn.ca/Help_and_Contact/Scenario_Types-e.html

• Canadian Climate Impacts Scenarios http://www.cics.uvic.ca/scenarios

Simple Scenarios

Simple scenarios, such as those referenced in the Scenario Tree can be highly useful in beginning to grapple with uncertainties in climate adaptation decisions. If time and information were free, it would be desirable to have complete, detailed forecasts of climate change (downscaled to an appropriate location). However, in practice, the range of alternatives available in a given context are highly constrained, and there may be little value of information associated with more detailed climate scenarios in selecting among these limited alternatives. Hence simple scenarios can help, and should be the first step in thinking through uncertainties for climate change.

Mountain Pine Beetle   

In a workshop to consider the effects of climate change on reforestation decisions after pine  beetle infestations, again only two scenarios were employed (TO BE EXPANDED)

Complex Scenarios

Coming soon...

Sockeye Salmon Climate Scenario
In a workshop to try to characterize and quantify how vulnerable sockeye salmon in the Fraser River System are to climate change, only two scenarios were employed. One involved an additional 2 degrees C in average annual temperature, over the recent normal period of 1976 to 1990. These two scenarios were 2 degrees C of additional warming over 60 years, and 4 degrees C of additional warming over 70 years. The 60 year period was 15 four-year lifecycles of sockeye salmon cohorts. These simple scenarios were deemed appropriate by the scientists participating in the workshop for two reasons:

(i) they had little or no specific knowledge of how warmer and wetter climate would affect the life cycle stages of sockeye salmon in this system.

(ii)