What climate scenarios are

Climate scenarios are plausible challenging and relevant stories about how the future climate may unfold.

Scenarios:

  • can illuminate the costs and benefits of different paths and provide guidance for action
  • can enable decision makers to experiment in relative safety in ways that prompt social learning and action
  • are typically based on assumptions about key driving forces such as greenhouse gas (GHG) emission pathways, land-use changes and socioeconomic factors
  • encompass a range of possible future outcomes. This allows users to explore uncertainties and understand potential consequences including those related to both decarbonisation and physical climate impacts
  • allow for ambiguity by providing a framework for understanding complex interactions and relationships
  • enhance our capacity to envision and prepare for diverse outcomes
  • help users understand different climate pathways that acknowledge the dynamic nature of possible trends and developments in mitigation, adaptation, and climate impacts. This is rather than basing the approach on a single climate projection.

See Staff guidance entity scenario development [External Reporting Board website]. 

What climate scenarios are not

Climate scenarios:

  • are not forecasts, projections, or predictions. They are narrative tools that offer a nuanced understanding of potential futures without implying certainty
  • do not provide probabilities or assign likelihoods to future outcomes. Development of scenarios does not involve describing the most likely scenario
  • are not about describing the preferred outcome. Climate scenarios are a tool for testing a range of plausible outcomes
  • are not the same thing as a climate strategy or plan but can be used as a tool to test the robustness of strategies or plans.

Why we plan for different climate scenarios

Many of the problems we face today, such as climate change, cannot be solved by traditional planning approaches.

Climate change is a complex problem with high levels of uncertainty that depend strongly on social, political, and cultural factors, as well as economic ones.

Scenario planning is most useful in situations where critical uncertainties are high

Levels of futures complexity ResizedImageWzYwMCwxODJd

Adapted from Sillmann et al. (2020)

The diagram shows levels from complete certainity to total ignorance.

The levels are:

  • Level 1: A clear enough future
  • Level 2: Alternative futures with probabilities
  • Level 3: Alternative futures with ranking
  • Level 4: A multiplicity of plausible futures
  • Level 5: An unknown future.

Diagram adapted from Sillmann et al. (2020). Event-Based Storylines to Address Climate Risk, Earth’s Future Vol 9, Issue 2.

Levels of futures complexity ResizedImageWzYwMCwxODJd

Adapted from Sillmann et al. (2020)

The diagram shows levels from complete certainity to total ignorance.

The levels are:

  • Level 1: A clear enough future
  • Level 2: Alternative futures with probabilities
  • Level 3: Alternative futures with ranking
  • Level 4: A multiplicity of plausible futures
  • Level 5: An unknown future.

Diagram adapted from Sillmann et al. (2020). Event-Based Storylines to Address Climate Risk, Earth’s Future Vol 9, Issue 2.

How climate scenarios can be used to test plans and policies

Climate scenarios provides a systematic approach for developing and testing plans and policies in the context of uncertain futures. It is particularly useful where there is high uncertainty and limited ability to control the risks.

They:

  • help make explicit different stakeholders’ assumptions about the ways in which things may unfold in the future
  • are particularly good at helping participants identify and articulate factors that drive future change, including physical climate hazards, social, political, economic, and cultural forces
  • provide a flexible framework that can integrate diverse forms of knowledge
  • can facilitate networking and learning across organisational and institutional boundaries
  • help to anticipate and deal with uncertainty and shocks
  • bring people together around multiple plausible visions of the future.

See Staff guidance entity scenario development [External Reporting Board]. 

Climate scenarios for the public sector

Government ministries and other public sector organisations face the need to make strategic decisions with uncertain future outcomes. These often involve multiple interacting stressors.

Making strategic decisions

Public sector organisation have to consider:

  • connections across spatial scales (local, regional, and global)
  • diverse forms of knowledge (indigenous, expert, local, quantitative, qualitative)
  • normative considerations (for example, to ensure fair and equitable socio-economic outcomes) that may require close consideration of power relations, rights and access, and social justice.

How climate scenarios can help

Climate scenarios can be used by public sector organisations to:

  • enhance understanding of external changes
  • help identify early warning signals of emerging problems and facilitate proactive responses
  • assist in surfacing and managing conflicts among societal interests
  • foster common ground for policymaking
  • trigger cultural changes for long-term adaptability.

Climate scenarios developed for a public sector organisation should reflect that the organisation is serving social, cultural, and environmental outcomes. This differs from private sector entities which are generally focused on financial implications.

Developing and applying climate scenarios

Public sector organisations should:

  • consider the complex context in which policy and planning decisions are made when developing and applying climate scenarios
  • acknowledge the need to tailor scenario development approaches to meet public sector organisations' unique purposes and mandates
  • emphasise the need to align scenario development with public sector entities' specific needs and functions.

Read more about scenarios in the public sector context

  • Policy Methods Toolbox: Scenarios [Department of the Prime Minister and Cabinet website] 
  • Guidance to Develop Climate Change Scenarios for Public Sector Planning and Policy: GNS Science Consultancy Report 2023 - to be published