Background
Thinking about the future is challenging, yet essential for planning environmental protection. One way scientists and policymakers approach this problem is by using scenarios—structured stories that explore how the world might change. Scenarios don’t predict the future. Instead, they help us understand how different choices and developments could shape environmental pressures, including chemical use and pollution.
There are two broad types of scenarios. Normative (goal‑oriented) scenarios start with a target and identify the steps needed to reach it. Exploratory scenarios examine what could plausibly happen under different social, economic or technological conditions. They help test how resilient systems and policies might be if the future unfolds in unexpected or challenging ways, including “what‑if” events such as floods, industrial failures or long‑term trends like climate change.
Exploratory scenarios are especially valuable for chemicals because chemical use is closely tied to societal behaviour, health, technology and the economy. A widely used set is the Shared Socioeconomic Pathways (SSPs), which outline contrasting but plausible global futures up to 2100:
SSP1 (Sustainability): A greener world with lower material use, strong environmental policies and rapid adoption of safer chemicals.
SSP2 (Middle of the Road): A continuation of historical trends, with moderate growth in chemical demand and gradual regulatory improvement.
SSP3 (Regional Rivalry): A fragmented world with weak cooperation, declining environmental standards and rising emissions.
SSP4 (Inequality): A divided world where affluent regions adopt cleaner technologies while poorer regions face high pollution burdens.
SSP5 (Fossil‑fueled Development): Rapid, resource‑intensive growth leading to high chemical production and emissions despite technological advances.
The SSPs are not predictions—they are “stories about what happened in the future,” helping researchers explore the consequences of different development pathways.
Because global scenarios are too broad for national‑scale questions, the SSPs have been downscaled for the UK. These UK‑SSPs are consistent with the global pathways but include UK‑specific characteristics. Each contains both numerical trends (e.g., population, energy use) and narratives describing how society evolves. This makes them particularly useful for exploring future chemical emissions. For example, population projections inform estimates of future demand for pharmaceuticals, while energy system trends help assess emissions linked to fossil fuels.
To estimate future chemical emissions, researchers begin by identifying the key drivers of chemical use. For pharmaceuticals, for example, these include population size and health, healthcare availability, imports and domestic production, and wider economic and social conditions. Exploratory scenarios describe how these drivers might shift over time.
Researchers then develop semi‑quantitative trends, using levels such as +++, 0 or --- to represent increases or decreases in these drivers under each scenario. These are refined through stakeholder input and expert review, then translated into quantitative values using real‑world data.
By linking scenario narratives, quantified trends and emissions models, scientists can project how chemical pressures on the environment might evolve. This helps identify potential hotspots, assess the effectiveness of current and future regulations and support forward‑looking risk assessments. Ultimately, scenario‑based forecasting helps ensure environmental policies remain effective under a wide range of possible futures.
Recorded lecture
Steve Lofts, who is an environmental chemist at UKCEH, describes how the shared socio-economic pathways can be used to forecast how chemical use and exposure might change in the future.
Key Reading
Desrousseaux A, Nagesh P, Gajraj R, Dekker S, Eitzinger J, Sallach JB, Boxall A, Kok K (2022). A shared socio-economic pathway based framework for characterising future emissions of chemicals to the natural environment. Futures, 144, 103040. DOI: doi.org/10.1016/j.futures.2022.103040.
Hader JD, Lane T, Boxall ABA, MacLeod M, Di Guardo A (2022). Enabling forecasts of environmental exposure to chemicals in European agriculture under global change. Science of The Total Environment, 840, 156478. DOI: doi.org/10.1016/j.scitotenv.2022.156478.
Nagesh P, Edelenbosch OY, Dekker SC, de Boer HJ, Mitter H, van Vuuren DP (2023). Extending shared socio-economic pathways for pesticide use in Europe: Pest-Agri-SSPs. Journal of Environmental Management, 342, 118078. DOI: doi.org/10.1016/j.jenvman.2023.118078.
Pedde S, Harrison PA, Holman IP, Powney GD, Lofts S, Schmucki R, Gramberger M, Bullock JM (2021). Enriching the Shared Socioeconomic Pathways to co-create consistent multi-sector scenarios for the UK. Science of the Total Environment, 756. DOI: doi.org/10.1016/j.scitotenv.2020.143172.
UK Climate Resilience Programme (2026) UK socioeconomic scenarios for climate research and policy.
UK Climate Resilience Programme (2026) Products of the UK-SSPs project.