ScenariosEmily McKenzie
2 April, InVEST Introductory Seminar, Bangkok
Outline
• What are scenarios?• Why use scenarios?• How to develop scenarios?• Some examples
Tell Stories, Use Scenarios
Valuation study in Bermuda
After
Before
Total values often less meaningful
• Bermuda’s reefs worth– $722 million p.a.– 10-17% of GDP
But what would be costs and benefits of new shipping channels?
What are scenarios?
• Plausible, simplified, descriptions of future
• Based on coherent & consistent assumptions:
– key drivers– their relationships– their impacts on
ecosystems
Despite their importance, environmental services are not normally included in resource decisions.
This is sometimes because it is hard to compare the benefits and costs of different options.
Why Use Scenarios?
Types of scenarios
• Interventions– Designs for policies, plans and projects
• Explorations– Possible but unexpected futures
• Visions– Perceptions of desirable or undesirable futures
• Projections– Depictions of the expected future
Yesterday
Today Tomorrow
The Future?
Interventions
Depictions of how additional, new interventions could be implemented, such as policies, projects or plans.
Explorations
• Explore possible future developments. • Anticipate unexpected future circumstances, test how policies cope with change.
Visions & Projections
Visions: Subjective depictions of possible futures that vary according to their desirability.Projections: Depictions of the expected future, without new interventions
Why use scenarios?
• Identify tradeoffs• Consider new policies• ‘Future-proof’ policies• Air conflicts, develop consensus• Learning• Storytelling
Scenarios for InVEST
• Scenarios as maps of land cover and/or coastal and marine habitats and uses.
• Scenario maps feed into InVEST to produce maps of ecosystem services for each scenario.
Example from Tanzania
Hopeful Expectations – poverty alleviation
Business as Usual
Example from Tanzania
Carbon storage on the current landscape…
Conservation 2025
Current
BAU 2025
Confidential draft, Feb 2009Thanks to Dr Ruth Swetnam
Comparison of carbon storage and sequestration in different scenarios…
2000 Conservation2025
BAU 2025
2.419 t/C
-8.65 7 t/Cor -3.6% of 2000 value -31.617 t/C
or - 13% of 2000 value
LOSS LOSS
Confidential draft, Feb 2009Thanks to Dr Ruth Swetnam
Scenario Development Methods
Bringing together multiple methods:• Qualitative: narrative stories of future
– Multi-stakeholder community visioning– Hand-drawn maps
• Quantitative: numerical estimates of future– Landscape optimization modeling – Computer-based land transition models
Drivers• any natural or human-induced factor that directly or
indirectly causes a change in an ecosystemRules• principles or conditions that prescribe how changes will
occur in the future
Others • Timeframe• Spatial scale & extent
Key Elements
Methods in Tanzania
– High stakeholder participation– Multiple stakeholder workshops, interviews– Time: 1 year – Capacity: 2 coordinators– Policy review
Step 2: Select the right scenario approach
Step 3: Develop scenario storylines
Step 4: Create scenario maps
Step 5: Assess ecosystem service outcomes
Step 6: Use and communicate results
Step 1: Understand scenarios
Key steps
Characteristics of effective scenarios
• Relevant• Legitimate• Plausible• Understandable• Distinct• Surprising• Scientifically credible• Comprehensive
• Iterative• Participatory
Photo credit: Josh Goldstein
• Scenario Development Guide– Picking the right scenario– Creating storylines, turning storylines into maps– NatCap case studies
• Scenario Generator – Simple, rule-based approach– % change from storylines
• InSEAM– Online collaborative map drawing software
• IDRISI Land Change Modeler– Around a dozen land cover transitions– Rules and constraints, taking into account historical trends
NatCap scenario tools
Central Sumatra Today
Sumatra Ecosystem
Vision
Government spatial plan
Sumatra
(60% more forest than
2008)
Same amount of natural
forest as 2008 (but likely
worse)
Hawaii
Issues of concern:-Effects of forestry and other industrial activities on aesthetic views-Effects of shellfish harvest and aquaculture on sensitive habitats
Any questions?
Scenario exercise #1
• Select one priority opportunity for InVEST to inform decisions in the GMS.
• Which services would you assess?
• Describe the scenario storylines you would compare in InVEST.