Shining a light on lesser-known pollutants reshaping our climate
We are a leading partner in a major Horizon Europe programme revealing the true impact of overlooked pollutants heating our planet.
When it comes to understanding climate change, the role of carbon dioxide in global heating has long been clear. But not all climate drivers are so well understood.
A group of substances known as non-CO₂ radiative forcers – including black carbon (soot), methane, and tropospheric ozone – also trap heat and disrupt the climate system, yet their exact impacts remain clouded in uncertainty.
Now, a major international research effort is bringing these lesser-known players into sharper focus. The €6.5 million Horizon Europe-funded Project FOCI is tackling some of the most persistent knowledge gaps in climate science.
Involving 17 research institutions and policy bodies, including the World Meteorological Organisation (WMO) and the World Health Organisation (WHO), the research aims to deepen understanding of how non-CO₂ forcers influence the climate, improve how they are captured in global and regional models, and help shape more effective climate policy.
At the heart of this effort is Ranjeet Sokhi, Professor of Atmospheric Physics and Director of the Centre for Climate Change Research at the University of Hertfordshire. Professor Sokhi is co-coordinator of FOCI, working alongside project coordinator Professor Tomáš Halenka of Charles University, Prague.
We know that short-lived climate pollutants like soot and ozone can have a significant impact, not just on global heating and weather patterns, but on air quality and public health. Yet confidence in how they are represented in global and regional climate models remains low. Our goal is to close these critical knowledge gaps and provide policymakers with clearer guidance on how to mitigate and adapt to their impacts.
Professor Ranjeet Sokhi,
Professor of Atmospheric Physics and Director of the Centre for Climate Change Research
Closing the climate confidence gap
These pollutants vary widely from region to region and interact with complex feedback mechanisms in the atmosphere. Many of the emissions that contribute to their formation – from agriculture, energy use, and land-use change – are poorly quantified.
FOCI aims to change that. By providing new insights into the origins, interactions, and cumulative impacts of these non-CO₂ forcers, the work is closely aligned with the science gaps identified by the Intergovernmental Panel on Climate Change (IPCC) in its Sixth Assessment Report.
Building on the university’s expertise in atmospheric and climate modelling and air quality research, Herts researchers are producing regionally relevant projections of how non-CO₂ forcers affect climate, weather, air quality, and health.
“We are going from the global scale right down to the local level,” says Professor Sokhi. “We want to understand how these pollutants contribute to climate-driven extremes like heatwaves, floods, and droughts, and how they influence patterns of human exposure to air pollution in cities.”
Learning from air quality challenges in Dubai
Professor Sokhi’s team brings valuable experience to FOCI from the UK-India collaboration PROMOTE, funded by the Natural Environment Research Council and India’s Ministry of Earth Sciences. This project developed new models to reduce uncertainties in air quality prediction and forecasting for Delhi. One of the most polluted cities in the world, Delhi faces a complex mix of emissions – not just from local sources such as traffic and industry, but from air pollution transported over long distances across the Indo-Gangetic Plain.
PROMOTE showed us how crucial it is to understand these wider atmospheric processes. A large share of the pollution affecting Delhi actually comes from outside the city, carried by regional winds and weather systems. That experience really reinforced the need for multi-scale analysis, from street level to regional and global, which is now a core principle of our work in FOCI.
Professor Ranjeet Sokhi,
Professor of Atmospheric Physics and Director of the Centre for Climate Change Research
Translating science into policy
Working with the WMO and WHO, the FOCI team’s findings will inform Europe’s green transition and feed into global policy frameworks, including the Paris Agreement and the IPCC’s Seventh Assessment Report.
Actions to reduce short-lived climate pollutants can deliver near-term benefits, helping to slow global temperature rise and improve quality of life for vulnerable communities.
“Reducing CO₂ remains essential, but it’s a long game,” says Professor Sokhi. “Targeting short-lived pollutants gives us a crucial opportunity to accelerate reductions in climate impacts and lessen the most immediate hazards – potentially avoiding as much as 0.6 degrees of warming by the middle of the century, based on estimates from the Climate and Clean Air Coalition. That’s huge in terms of protecting people and ecosystems.”
Project FOCI has been co-funded by the European Union with funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No. 101056783 and from UKRI under the UK Government’s Horizon Europe Guarantee (UKRI Reference Numbers: 10040465, 10053814 and 10050799).
Professor Sokhi
Professor of Atmosphere Science and Atmospheric Physics
Ranjeet Sokhi has a dual role as the Director of the Centre for Atmospheric and Climate Physics Research (CACP) and of the Centre for Climate Change Research (C3R). He has nearly 200 publications with his research focusing on physical and chemical processes affecting air quality, exposure and health impacts on street, city and regional scales. He is an advisor for DEFRA, WHO, WMO and PHE and was a member of the UK Government’s Air Quality Modelling Steering Group and the Prediction Capability subgroup of AQSELG. He has participated in or coordinated a large number of projects and networks for NERC (e.g. PI of APHH PROMOTE), EC (e.g. TRANSPHORM. EMERGE), Environment Agency and industry. As a PI for NCAS he coordinates the development of the UK Air Quality Forecasting system. He is also the Chair of WMO/GURME Science Advisory Group and coordinator of WMO/GAW PREFIA project on Air Quality Prediction for Africa. has been the chair of the series of International Conferences on Air Quality – Science and Application since 1996.