It’s impossible to know exactly what the future will bring, but modeling can help us predict or forecast possible future outcomes.
Population Council researchers develop demographic projections based on globally used and agreed-upon scenarios to help us understand the complex interplay between people and the climate. How will the changes we make or fail to make over time affect our future?
These scenarios are called the Shared Socioeconomic Pathways (SSPs). They describe five alternative paths of how global societies might change with respect to population growth and distribution, composition, economic inequality, urbanization, energy use, and technological advancements.
Understanding these patterns of development is a critical step that allows us to integrate our work with climate models—and understand how people and climate change will affect one another. The SSPs are storylines to describe future societies. Here are three that we commonly use:
| Scenario | Description | Impacts |
|---|---|---|
| SSP2 | Middle of the road scenario, with medium assumptions on fertility, mortality, migration, urbanization, and economic development | Both adaptation capacity of the population and mitigation strategies to contain climate change are moderate |
| SSP3 | Societies with low fertility, high mortality, and low migration with slow economic growth and weak and malfunctioning institutions to tackle climate change effects | People are more vulnerable and less prepared to tackle climate change effects, although environmental hazards are less severe due to slower economic growth and therefore lower emissions |
| SSP5 | Societies with high fertility, extensive urbanization, low mortality, high migration, and rapid economic growth but with insufficient actions to contain climate change | People have high adaptive capacity at the cost of more reliance on fossil fuels, which leads to higher emission levels and more severe climate change |
The Community Demographic Model (CDM), a modeling system and integrated tool, follows the SSP framework and allows users to explore socio-demographic trajectories and changes in population size, household configuration, urbanization trends, and the spatial distribution of people across the different SSPs.
We are continuing to refine our models, expanding the geographic areas we include, adding more population characteristics, and digging deeper down (from country level, to subnational, and even within individual cities).
Here is an example of our current projections of the spatial distribution of population for the state of Oregon in 2050:
These three maps highlight the spatial pattern of population and urbanization in the state of Oregon under three SSP scenarios. Under SSP5, Oregon will have a much larger population, with a more sprawling urban pattern. Under SSP3, we expect a smaller, more scattered population with fewer urban centers.
We can integrate this type of information with critical climate and environmental information; for example, to explore how patterns of urbanization and population arrangement relate to biodiversity loss, or how the size and spread of population relate to exposure to future heat waves, wildfires, and severe urban air pollution. This analysis can help determine future urban planning needs, and the potential infrastructure damage, financial asset loss, and deaths due to climate change. This is particularly of concern under SSP3—where adaptive capacity of society will be lower (meaning they are less able to cope with climate events)—or SSP5 where these climate hazards are predicted to be more frequent.
Our models highlight different potential futures for Oregon. One approach to minimize this risk is to invest in green and sustainable approaches such as smart cities with equitable economic opportunities for people with various backgrounds, efficient agricultural practices to preserve biodiversity, and investment in renewable energy to contain greenhouse gas emissions.
The size and shape of our future cities are opportunities for better transportation, connectivity, and access to resources, but they must be built equitably and planned for our climate future.