Scenarios

Emily 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?

Example of Scenarios

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Kakawis

OpitsatYarksis

Clayoquot

Tofino

Compare options

") Additional Floathomes

") Existing Floathomes

Oyster Aquaculture

Eelgrass

Risk to Habitats

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

Net benefitsfrom coastal

ecosystem

Time

Net benefitsfrom coastal

ecosystem

Time

Benefitswith MPA

MPA implementation

Cost of MPA

Benefits without MPA

Costs ofmanagement

Benefits of management

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 need to:

• Describe a possible future

• Reflect uncertain developments or choices

• Be spatially explicit (or can be)

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

Methods in Tanzania

– Compare ecosystem service outcomes with ‘hopeful future’ (poverty alleviation policies) versus business as usual.

– Methods: qualitative + quantitative– Time: 1 year – Capacity: 2 coordinators– Participation: high, multiple stakeholder workshops

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

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

Drivers

• Social and demographic– E.g. population growth

• Technological– E.g. innovation

• Economic– E.g. commodity prices

• Environmental – E.g. climate change

• Political– E.g. Land tenure

Scenario drivers in InVEST

• Terrestrial and freshwater– Land cover or land use (e.g., agriculture)– A change in management practices (e.g., crop type)– Other assumptions (e.g., how far people are willing to travel

to harvest a forest product)

• Marine InVEST– Human uses of the coast and ocean (e.g., fishing)– Coastal and near-shore habitat distribution– Coastal development– Land cover or land use

Converting storylines into maps

• Drawing maps– Work with stakeholders to draw a map for each scenario

using paper, digital or online mapping tools

• Trend analysis– Use past experience and statistical methods to predict where

change is most likely to occur on the landscape or seascape.

• Rule-based approaches– Use rules based on social, economic or biophysical principles

that define which areas are likely to be most suitable for particular uses or activities

Aspects of LC change rules must reflect

• Type of LC change– e.g. conversion from forest to agriculture

• Magnitude and time frame of LC change– e.g. 15% over 10 years

• Spatial and temporal dimensions of LC change– e.g. forests bordering agriculture are converted first

Types of rules

• Biophysical rules– Climate, e.g. rainfall – Topography, e.g. slope, elevation – Soil, e.g. type, depth

• Socio-economic rules– Accessibility, e.g. infrastructure, population density – Governance, e.g. land tenure, protected areas – Demography, e.g. poverty, education

• Threshold rules, e.g. LC expands at < 2,000 meters altitude• Location rules, e.g. LC expands in forest reserves• Rate rules, e.g. LC expands at historical rate until 2015 then slows • Toggle rules, e.g. LC does not expand in protected areas

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

Common challenges

• Knowing why and how to start • Selecting the right approach• Engaging stakeholders effectively• Finding data• Creating contrasting scenarios• Settling with compromise

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?