About a decade ago, a group of climate scientists described five scenarios for the future. Called the Shared Socioeconomic Pathways (SSPs), these scenarios suggest how socioeconomic development could evolve in worlds with differing challenges to climate adaptation and mitigation.
One SSP, “Sustainability,” envisions a collective shift toward green energy, reducing economic inequities and investments in research and development. Another, “Regional Rivalry,” paints a picture of a world riven by nationalism and fighting over resources. In that future, high levels of conflict stifle economic development. Rich countries see slower population growth, while birth rates increase in poorer nations.
Scientists and policymakers use SSPs to project how today’s choices affect tomorrow’s world. But for complex subjects like public health, these intentionally simple scenarios don’t capture every complexity. Under the SSP “Fossil-Fueled Development,” for example, the world doubles down on fossil fuels, spurring rapid economic growth. That growth, according to the scenario, would spur investments in education and health. But at the same time, increased emissions would degrade the environment, exacerbating health risks.
That description leaves many public health questions unanswered: Would hospital systems be better prepared to handle the increased volume? Could more frequent heat waves lead people to spend more time inside, amplifying mental health burdens?
Last year, a group of 63 experts in climate change and health met in Vienna to extend the SSPs to better reflect the dynamic nature of public health over the course of the century. Their expanded narratives, published Oct. 5 in The Lancet Planetary Health, provide comprehensive visions of possible population health and health system development and explore how communities might better prepare for shifting future health risks.
Carole Green, a UW doctoral student in environmental and occupational health sciences, attended the workshop and is lead author of the accompanying paper. UW News sat down with Green to talk about where previous climate scenarios fell short, the conference’s work and how we can better prepare to keep each other safe in an uncertain future.
What are the Shared Socioeconomic Pathways, and how do we use them?
Carole Green: Shared Socioeconomic Pathways are a narrative framework that can be used in conjunction with pathways of greenhouse gas emissions to project future climate impacts to 2100. The SSPs are basically descriptions of the societal choices that affect the magnitude and pattern of interventions to protect human health and well-being.
The SSPs are essentially five possible alternatives for our future world. These pathways have been expanded to incorporate a wide range of issues of relevance for public health, and have been downscaled to describe what the future might look like in different countries and regions.
SSPs are featured in global processes like United Nations climate conferences, where negotiators come from around the world to debate and agree on approaches to build resilience and sustainability to climate changes. The models help us understand how those choices interact and what the effects might be.
We also use the SSPs in health research to understand the possible magnitude and geographic pattern of health impacts from climate change over the course of this century. Many projects at UW use future warming levels to analyze things like future wildfire impacts on Washington residents (research done by UW’s Climate Impacts Group).
What do the SSPs leave out?
CG: SSPs assume that humans will make socioeconomic changes in the future. The changes described in the pathways originally quantified GDP and population changes. Our work adds complexity, specifically to understand how the future of public health could evolve under these five pathways.
A lot of people are interested in heat waves, for example. Climate modeling alone can capture the planet’s warming, but doesn’t consider issues like how access to hospitals and healthcare could change by 2100. Current heat wave modeling looks at the climate interactions that shape health impacts but don’t explore how concurrent changes in society could interact with climate change to impact people’s well-being.
Once you added complexity into the SSPs, what changed in your understanding of possible futures? Did you learn anything new or surprising?
CG: We learned that the drivers of health impacts are complex, and many are neither entirely good nor bad. Prioritizing sustainability, mitigation and adaptation will not necessarily lead to the best world for each future health outcome, but it definitely affects the future of health and well-being. Health futures we face globally are not predetermined. Different pathways could lead to vastly different health outcomes, with governance, health-system capacity, resources, equity, and cross-sectoral factors such as water and energy playing critical roles.
For example, under one of the scenarios, people don’t prioritize reducing greenhouse emissions, focusing instead on adapting to the changing climate. Strong investment in technology leads to quite a lot of wealth, which can benefit some health outcomes. But it’s not ideal, because people would also have to spend more time indoors because of the growing heat burden and would have to reduce connection to the outdoors and nature. You really don’t want to live in that scenario.
It’s very much a mix, which is challenging.
Now that we have these fleshed-out scenarios, what does that allow us to do?
CG: It allows us to have a more complex understanding of future health risks from climate change. Now we can add a layer of understanding and think about more variables than just warming levels and population numbers. It’s made of a lot of complexities that affect health, and those have their own effects.
In future climate scenarios, what does access to healthcare look like? What is the extent of food insecurity? How are we making sure people have access to clean air and water? When we have some understanding of those interactions, then it can motivate decision-makers to develop appropriate policies.
What comes next?
CG: We will apply these narratives to six different countries where there has been limited research using the SSPs. We’re working in Brazil, Senegal, South Africa, India, Vietnam and the Solomon Islands. We’ve started identifying key leads across these countries, where there is quite an appetite for this research. All countries are required to develop national health adaptation plans and to conduct vulnerability and adaptation assessments. They are also interested in modeling future health risks. We want to explore the extent to which the SSP narratives apply in their country’s context. Do they fit? How would they look different? There’s a lot of interest in building on local knowledge and bringing local experts together to talk about possible futures.
We’re also quantifying specific disease burdens, universal healthcare access, water and sanitation infrastructure and digital health. Some quantifications will look at pairing SSPs with certain warming levels to project impacts.
Last question: This group — including dozens of the world’s leading experts on climate and health — chose you to write the paper. How did that happen?
CG: I am definitely not the leading expert in that room, so it was very much an honor to work on this and lead the writing. A lot of it comes from my advisor, Kristie Ebi, who is very supportive of me and my work. That’s been really meaningful. She encouraged me to take this on.
I often tell people that my job is to listen to experts and write down what they say. It was very meaningful to get to make those connections.
For more information or to reach the researchers, contact Alden Woods at acwoods@uw.edu.
Journal
The Lancet Planetary Health
Method of Research
Commentary/editorial
Subject of Research
Not applicable
Article Title
Navigating global health futures under the Shared Socioeconomic Pathways
Article Publication Date
5-Oct-2026
COI Statement
All authors declare funding received from Wellcome for travel to the Vienna workshop in June, 2025. BvR, CG, MA, JJH, SP, SS, and KLE declare funding under Wellcome grant 313527/Z/24/Z. JCS declares funding from EU’s Horizon Europe research and innovation programme under grant agreement numbers 101057554 (IDAlert) and 101060568 (BEPREP). AM declares funding from Wellcome grant 225997/Z/22/Z for the CLIMate SEnsitive DISease Forecasting Tool (CLIMSEDIS) project. CC declares support from the Wellcome Trust for the CLIMSEDIS and Wellcome grant 308964/Z/23/Z for A Changing Climate Impact Monitoring and Assessment Toolbox for Irish Seas projects. YP-S declares support from the Wellcome Trust (grant 304972/Z/23/Z). DvV declares funding from the European Research Council under the Horizon Europe programme The Platform for the International Coordination of Automated Frequency Restoration and Stable System Operation (grant agreement ID 819566). KLE additionally declares grants from National Institutes of Health and the World Meteorological Organization; consulting fees from SouthSouthNorth for UK Foreign, Commonwealth and Development Office and Burroughs Wellcome; honoraria for university lectures; travel support from the Royal Society Wolfson Visiting Fellowship and the National Academy of Sciences; and unpaid leadership roles with START, the Future Earth Assembly, and the Micronutrient Forum. PP declares travel support to attend the Novo Nordisk Foundation Global Science Summit in June, 2024 and participation in the Healthy Environments and Lives Network International Reference Group and the Global Climate and Health Alliance Board of Directors. All other authors declare no competing interests.
