Scenario process Next steps

New scenarios (Share Socio-economic Pathways)

New scenarios (Share Socio-economic Pathways) Scale issues Using these global scenarios to build local scenarios and analyze actual decisions

New scenarios (Share Socio-economic Pathways) Scale issues Using these global scenarios to build local scenarios and analyze actual decisions Content issues Define/refine scenarios to make them appropriate for various decisions

New scenarios (Share Socio-economic Pathways) Scale issues Using these global scenarios to build local scenarios and analyze actual decisions Content issues Define/refine scenarios to make them appropriate for various decisions Relevance issues Determine what scenarios are most relevant for a given question

New scenarios (Share Socio-economic Pathways) Scale issues Using these global scenarios to build local scenarios and analyze actual decisions Content issues Define/refine scenarios to make them appropriate for various decisions Input for new generation through aggregation Relevance issues Determine what scenarios are most relevant for a given question

Scale issues

From global scenarios to local decisions Most decisions require local-scale scenarios: – Health effects of local pollution depends on transportation, which in turn depends on: local choices (e.g., urban sprawl policy) global choices (e.g, oil price, availability of electric cars) – Natural disaster impacts depends on infrastructure, which in turn depends on: local choices (e.g., do we build dikes?) global choices (e.g., what foreign aid to build infrastructure?)

Global scenarios as boundary conditions Global scenarios = boundary conditions for local scenarios No automatic and deterministic link between global and local scenarios, but a set of constraints: – a local scenario with local degradation in governance quality is consistent with a global scenario with improved governance – a local scenario with 100% electric cars is not consistent with a global scenario without electric cars.

Global vs. local scenarios

Step 1: Defining global scenarios

Global vs. local scenarios Step 2: Downscaling from global scenario to local scenario Step 1: Defining global scenarios Scenario for urban extension in Paris up to 2100

Global vs. local scenarios Step 2: Downscaling from global scenario to local scenario Step 3 Aggregation of many local scenarios into new global scenarios? Step 1: Defining global scenarios Scenario for urban extension in Paris up to 2100

Content issues

Scenario variables for health issues? In the previous generation of scenarios, many variables were missing for relevant health issues: – Nothing on inequality within countries – Nothing on governance and development of health insurance – … In the new generation, “extended” Share Socioeconomic Pathways to include more variables: – Work is needed to identify what is required – Work is needed to create the corresponding quantitative or qualitative information

Relevance issues

Relevant scenarios for one questions An infinity of possible futures… … but practical reasons to have only a small set of scenarios We will have 5 Shared SocioEconomic Pathway (SSP). These SSPs have been chosen to inform most decisions on mitigation and adaptation.

From many possible futures…

… selection of a few representative ones

CO2 emissions in the baseline Depending on how we define our indicators of capacity to adapt and capacity to mitigation, the distribution of scenarios is different

GDP per capital of the 20% poorest in a selection of developing countries CO2 emissions in the baseline Depending on how we define our indicators of capacity to adapt and capacity to mitigation, the distribution of scenarios is different Emission in baseline

GDP per capital of the 20% poorest in a selection of developing countries CO2 emissions in the baseline Depending on how we define our indicators of capacity to adapt and capacity to mitigation, the distribution of scenarios is different Emission in baseline GDP cost to reach 550ppm Share of agriculture in GDP

GDP per capital of the 20% poorest in a selection of developing countries CO2 emissions in the baseline Depending on how we define our indicators of capacity to adapt and capacity to mitigation, the distribution of scenarios is different Emission in baseline GDP cost to reach 550ppm Share of agriculture in GDP Ideally, we would have different SSPs for each research question or policy analysis Toward a large dataset of scenarios?

Relevant scenarios for one questions We will have 5 Shared SocioEconomic Pathway (SSP). These SSPs have been chosen to inform most decisions on mitigation and adaptation. But certain decisions will require different scenarios: – To work on water-borne illness, having scenarios that differ by the oil price may be useless. – To work on local air pollution in cities, it is critical to have varying assumptions on oil price. Long-term objective: a large dataset of scenarios and a process to select a set of few scenarios for each decision or research question Question: for various health issues, what differences across scenarios do we need to perform an unbiased sensitivity analysis? – Differences in demographics (aging) – Differences in economic conditions (income, job) – Differences in access to services (drinking water) – Should they be correlated?

New scenarios (Share Socio-economic Pathways) Scale issues Using these global scenarios to build local scenarios and analyze actual decisions Content issues Define/refine scenarios to make them appropriate for various decisions Input for new generation through aggregation Relevance issues Determine what scenarios are most relevant for a given question