Commenting in Nature Medicine, researchers from the Pathfinder Initiative at the London School of Hygiene & Tropical Medicine and the Aga Khan University argue that robust evaluations of climate and health interventions are needed to identify effective actions and assess unintended harms. They highlight the need to build climate and health intervention trials capacity, and call for global collaboration between researchers, funders and international organisations to scale up intervention research and advance the climate and health agenda. 

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Cities play a vital role in the transition to a healthy, net-zero future. Although cities are a major source of greenhouse gas emissions, many are already leading the way in implementing climate solutions that can bring major near-term benefits to health. 

A new analysis of city-level reporting of climate actions shows that while most cities report co-benefits related to climate mitigation actions (actions to reduce greenhouse gas emissions), many fail to report health co-benefits. Health co-benefits were reported for less than half (44%) of all reported actions with co-benefits, while economic benefits were reported for almost 70%. 

The findings suggest a gap between potential and recognised health benefits, and highlight the need for greater awareness of the health co-benefits of climate mitigation among city-level policymakers to accelerate a healthy, net-zero transition. 

The study, published in Nature Partner Journals (npj) Urban Sustainability, was led by researchers from the London School of Hygiene & Tropical Medicine as part of the Pathfinder Initiative. 

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The 2025 World Health Summit took place from 12 to 14 October in Berlin, focusing on the theme ‘taking responsibility for health in a fragmenting world’. The summit brought together key actors in global health from all sectors and regions to discuss solutions to tackle urgent public health challenges. 

The Pathfinder Initiative, in collaboration with the African Population Health Research Center (APHRC), National Academy of Medicine, and WHS Alliance, hosted a session at the summit with the title ‘Climate in crisis, health at risk: equitable strategies for a net-zero world’. The session aimed to explore ways to improve health and save lives through ambitious policies and actions to cut greenhouse gas emissions and address climate impacts. Speakers presented diverse perspectives but with the common thread of emphasising the urgency of and opportunities for climate and health action.  

Speakers included: 

• Joy Phumaphi (moderator), Co-Chair of the Lancet Pathfinder Commission and Executive Secretary of the African Leaders Malaria Alliance

• Carsten Schneider, Federal Minister at the Federal Ministry for the Environment, Climate Action, Nature Conservation and Nuclear Safety of the government of Germany

• Professor Andy Haines, Professor of Environmental Change and Public Health at the London School of Hygiene & Tropical Medicine and Co-Chair of the Pathfinder Initiative

• Dr Elizabeth Kimani-Murage, Lead of Nutrition and Food Systems at APHRC and part of the Pathfinder Initiative team; Dr Victor Dzau, President of the National Academy of Medicine (NAM)

• Dr Ethel Maciel, Special Envoy for COP30 and Secretary for Health and Environment Surveillance of the Brazilian Ministry of Health

• Dr Vincent Bretin, Director of Climate and Health at Unitaid

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The 2025 Planetary Health Annual Meeting took place from 6 October to 10 October in Rotterdam, bringing together experts from a range of disciplines and backgrounds with the aim of sharing knowledge, and exploring challenges and solutions for planetary health.

The Pathfinder Initiative hosted a parallel session at the conference, with the title ‘Advancing solutions for planetary health: insights from the Pathfinder Initiative’. Speakers included: Dr Iris Blom (moderator) from the London School of Hygiene & Tropical Medicine (LSHTM), Pathfinder Initiative, and World Health Organisation; Dr Lorna Benton (LSHTM and Pathfinder Initiative), Dr Peninah Murage (LSHTM and Pathfinder Initiative), Dr Emma Hutchinson (LSHTM), Dr Elizabeth Kimani-Murage (African Population and Health Research Center (APHRC) and Pathfinder Initiative); and Dr Rebecca Newbould (LSHTM and Pathfinder Initiative).

The session featured evidence on the health benefits of climate action across sectors, findings from reviews of evidence on the health benefits of nature-based solutions and on climate and health action in cities, and learnings from research, knowledge sharing and capacity strengthening work in Africa. 

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The second Africa Climate Summit, hosted by the Government of Ethiopia in collaboration with the African Union, took place in Addis Ababa, Ethiopia, from 8-10 September, focusing on the theme ‘Accelerating Global Climate Solutions: Financing for Africa’s Resilient and Green Development’.

The African Institute for Development Policy (AFIDEP), Pan African Climate Justice Alliance (PACJA), Amref Health Africa, and the London School of Hygiene & Tropical Medicine (LSHTM) hosted a high-level policy dialogue on ‘Pathways for integrating health into Africa’s climate change adaptation, mitigation and resilience strategies’ to explore ways to embed health into regional and national climate policies in Africa. 

On the sidelines of the summit, AFIDEP and LSHTM also hosted a workshop to discuss the establishment of a new Community of Practice on climate action and health in Africa. Participants of the workshop were invited to join and help shape the development of the Community of Practice. 

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Growing evidence highlights the links between climate and health, but stronger guidance that considers connections between natural and human systems is needed to inform the evaluation of interventions with climate and health goals.

In a new paper, published in the BMJ, researchers from the Pathfinder Initiative research team at the London School of Hygiene & Tropical Medicine (LSHTM) make the case for updated guidance that strengthens consideration of the wider system in the design and evaluation of policies and actions that address climate and other environmental and health challenges.

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During London Climate Action Week (LCAW) 2025, the 7th and largest LCAW to date, the Pathfinder Initiative and partners hosted a two-part conference at the London School of Hygiene & Tropical Medicine (LSHTM), with the title ‘From global evidence to local action on climate and health’.

The first session, hosted by LSHTM, UK Health Alliance on Climate Change (UKHACC), C40 Cities and University College London (UCL), focused on ‘health as the driver for sustainable cities’.

The second session, hosted by the Climate and Clean Air Coalition (CCAC) and LSHTM, explored the latest science, tools, and strategies for tackling super pollutants, and delivering immediate benefits for climate, clean air, and public health. 

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The Pathfinder Initiative, C40 Cities, Youth for Unity and Voluntary Action (YUVA), and the Zurich University of Applied Sciences (ZHAW) hosted a side event at the Bonn Climate Change Conference (SB 62) to explore how cities can play a key role in driving climate action and accelerating healthy and just urban transitions.

Speakers included Lord Mayor Dr Jane Lomax-Smith of the city of Adelaide, and experts from LSHTM, YUVA, ZHAW and the C40 x GCoM Joint Program. Dr Lorna Benton, Research Fellow at LSHTM, presented research from the Pathfinder Initiative on the importance of evaluating the impact of interventions, and work to produce guidelines for evaluation.

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The Pontifical Academy of Sciences has published a book ‘From Climate Crisis to Climate Resilience’, following its three-day summit of the same name at the Vatican in May 2024.

Professor Andy Haines, Co-Chair of the Pathfinder Initiative, made a speech at the summit, highlighting findings from the Lancet Pathfinder Commission Report on pathways to a healthy net-zero future. Insights from the speech, Commission report and wider Pathfinder Initiative are published in a chapter in the new book.

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The U.S. National Academy of Medicine (NAM) has launched a Roadmap for Transformative Action to Achieve Health for All at Net-Zero Emissions, a global initiative to place health at the centre of climate action.

To lead this work, NAM has convened a diverse international Commission, co-chaired by Professor Victor Dzau, President of NAM, Professor Andy Haines, co-Chair of the Pathfinder Initiative and Professor of Environmental Change and Public Health at LSHTM, and Dr Judith Rodin, President emerita of the University of Pennsylvania and former President of the Rockefeller Foundation.

Commenting on the Roadmap, Professor Haines said: “Perhaps the biggest challenge the Roadmap aims to tackle is precisely how to effect this transformation. The work aims to realistically guide systems change, identifying enablers and barriers to advance shared goals around climate change, sustainability, and health for all.”

To inform its final report, NAM is organising a series of workshops, starting with The “What” of Systems Transformation: Anchoring Climate Action in Health, on April 29 and 30, 2025.

A number of experts from the Lancet Pathfinder Commission and Pathfinder Initiative research teams are members of the NAM Roadmap Commission, and evidence from the Pathfinder Initiative on the health benefits of climate action has helped to inform the development of this important initiative.

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A new study led by researchers from the Pathfinder Initiative research team at the London School of Hygiene and Tropical Medicine, in collaboration with experts from Muhimbili National Hospital in Tanzania, LEAD Foundation Tanzania, and Conservation International in Kenya, shows the potential for environmental solutions where trees are a central feature to provide significant health benefits, but community needs must be carefully considered.

The first review of its kind, published in The Lancet Planetary Health, found compelling evidence that tree-based interventions in low- and middle-income countries (LMICs) could improve agricultural yields, dietary diversity, household income, child growth, and self-reported wellbeing, while encouraging the sustainable use of forest resources.

The findings of the review suggest, however, that without careful consideration of impacts, some activities aimed at protecting or restoring the natural environment may compromise the wellbeing and livelihood of the implementing or surrounding communities. For example, people could lose income from a reduction in timber production, although this loss could be offset by income from non-timber forest products.

The review also found potential benefits varied by the type of intervention. Solutions with a strong focus on livelihood improvement such as agroforestry (adding trees to farms) had more positive impacts compared to solutions where the main objective is to reduce carbon emissions or conserve biodiversity, such as REDD+ (Reducing Emissions from Deforestation and forest Degradation) and protected areas.

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New evidence strengthens the health and economic argument for ambitious climate action, with substantial near-term benefits to be gained through cleaner air, improved diets, and increased physical activity.  

In addition to being essential for limiting global warming, measures aimed at achieving net zero are also public health policies, according to a new study published in The Lancet Planetary Health. 

The study, led by researchers at the Institut de Biologie de l'Ecole Normale Superieure-PSL (IBENS), the Conservatoire national des arts et métiers (Cnam, Paris), and INSERM, in collaboration with researchers from the Pathfinder Initiative research team at the London School of Hygiene & Tropical Medicine (LSHTM), provides further compelling evidence on the major benefits that effective climate policies can bring to health and economies globally. 

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Members of the Pathfinder Initiative research team at LSHTM and researchers at LSHTM's Global Health Economics Centre are collaborating with the Euro-Mediterranean Center on Climate Change in Italy and the Office of Health Economics in the UK on a new Wellcome Trust-funded project focusing on the economic evaluation of the health impacts of climate action. Project partners will review existing economic evaluation methods; identify gaps in research capacity and uptake; bring together key stakeholders including economists, researchers and users of climate and health data; and provide guidance to inform future evaluations. 

Interested stakeholders from diverse disciplines, geographies and sectors are invited to sign up to get involved. 

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As leaders and stakeholders from around the world gathered for COP29 in Baku, the Pathfinder Initiative reiterated the need to integrate health into all climate policies, and the major health benefits that can be achieved from ambitious climate action across all sectors.

The Pathfinder Initiative research team presented findings and recommendations from the Lancet Pathfinder Commission report and wider Pathfinder Initiative at the following events:

Health co-benefits of climate action, ATACH Day, Health Pavilion

Professor Andy Haines, Co-Chair of the Pathfinder Initiative and Professor of Environmental Change and Public Health at LSHTM, gave a keynote speech on behalf of the Pathfinder Initiative at this session hosted by the World Health Organization. The presentation highlighted evidence on the health co-benefits of climate action, and how to capitalise on these health co-benefits through effective action across all sectors.

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Climate Change and Health: Crafting Policies for Africa's Urban Future, OECD Pavilion

This event, hosted by the Organisation for Economic Co-operation and Development (OECD), brought together researchers, government representatives, and representatives from international institutions to discuss how climate mitigation policies can shape health outcomes across cities in Africa, and how a systems thinking approach can contribute to these efforts. Members of the Pathfinder Initiative team and Lancet Pathfinder Commission took part in the panel and shared insights on challenges and opportunities for African cities to implement policies that bring climate and health benefits.

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From 29-31 October, key stakeholders in climate and health came together for the inaugural Climate and Health Africa conference, hosted by CeSHHAR Zimbabwe in collaboration with the Zimbabwean Ministry of Environment, Climate and Wildlife and the Ministry of Health and Childcare. As part of the second phase of the Pathfinder Initiative, project partners including the African Institute for Development Policy (AFIDEP), the African Population and Health Research Center (APHRC) and the London School of Hygiene & Tropical Medicine (LSHTM), hosted a workshop on the sidelines of the Climate and Health Africa conference focusing on identifying gaps and needs in research and policy for capacity-strengthening work in sub-Saharan Africa.

Ahead of the conference and workshop, Dr Elizabeth Kimani-Murage, Alice Ritho and Dr Kanyiva Muindi from APHRC shared insights on challenges and opportunities for climate and health in Africa.

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The Global Evidence Summit, hosted by Cochrane, JBI, Guidelines International Network (GIN) and the Campbell Collaboration, took place in Prague from 10-13 September to explore evidence generation and dissemination for action across different sectors, including health, education, social justice, the environment and climate change.

The Pathfinder Initiative took part in a panel discussion on “Climate change adaptation, mitigation and health policy: towards an integrated field”, focusing on advancing evidence-informed policy and practice in the field of climate change and health. Andy Haines, Professor of Environmental Change and Public Health at LSHTM and Co-Chair of the Pathfinder Initiative, presented on the need to develop and implement evidence-informed policy, highlighting findings from the Pathfinder Commission report. Hugh Sharma Waddington, Assistant Professor at LSHTM and part of the LSHTM Pathfinder research team, also presented findings from Pathfinder research and emphasised the importance of integrated efforts to generate evidence on climate and health using modelling and evaluation.

Jan Minx from the Mercator Research Institute on Global Commons and Climate Change chaired the session and panellists included Isabel Fletcher (Wellcome Trust), Ruth Steward (Future Evidence Foundation), and Lisa Askie (World Health Organisation). Building on discussions at the What Works Climate Solutions Summit in June, speakers highlighted the need to mainstream health into the climate agenda and put health at the centre of the evidence building for action.

The LSHTM Pathfinder Initiative research team and partners took part in the What Works Climate Solutions Summit from 9 to 12 June in Berlin to discuss evidence-based climate policy.

Andy Haines, Co-Chair of the Pathfinder Initiative and Professor of Environmental Change and Public Health at LSHTM, presented findings from the Lancet Pathfinder Commission report in a keynote speech. The Pathfinder Initiative also hosted a session on “Aligning evidence on climate change mitigation and health”, presenting findings from a workshop on the health co-benefits of climate mitigation and highlighting ways forward for research, policy and action on climate and health.

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The Pathfinder Initiative, in collaboration with the What Works Climate Solutions Summit, hosted a workshop on 30 April and 1 May, focusing on the health co-benefits of climate mitigation. Speakers and participants explored what works in climate policy, under what conditions and why. Experts from a range of disciplines and backgrounds discussed challenges and opportunities in research and policy, and how to build a robust evidence base on climate mitigation and health to inform decision making at all levels. 

Results from the workshop will be used to inform evidence reviews, guidelines, checklists and data harmonisation methods under development as part of the second phase of the Pathfinder Initiative. The workshop outputs will also inform the programme of work at the main summit in June 2024 and will be presented at a session on Aligning evidence on climate change mitigation and health insights from the Pathfinder Initiative and partners.

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The 2024 Planetary Health Summit and Annual Meeting (PHAM) took place on 16-19 April at Sunway University in Malaysia, bringing together over 1000 participants from 63 countries. The first PHAM hosted in an Asian country covered a range of topics relating to planetary health including the health effects of air pollution, the use of AI, planetary health in education, impacts on mental health, food systems, healthcare systems, and indigenous knowledge.

Researchers from the London School of Hygiene & Tropical Medicine – Prof Andy Haines, Tamzin Reynolds, and Blanca Anton – were among presenters, highlighting key findings from the report of the Lancet Pathfinder Commission and broader Pathfinder Initiative on the health benefits of climate mitigation actions. Evidence from the Pathfinder Initiative featured in sessions focusing on planetary health research and turning planetary health and earth system science into beneficial action.

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Johan Rockström, Director of the Potsdam Institute for Climate Impact Research and a member of the Lancet Pathfinder Commission, has been awarded the 2024 Tyler Prize for Environmental Achievement for his pioneering work on the “Planetary Boundaries” framework, a scientific guide to help keep the planet in a safe operating space.

The Tyler Prize Executive Committee awarded the prize to Professor Rockström for his “science-based approach to sustainable development for people on a stable and resilient planet”, citing the need for a holistic, interdisciplinary approach to the mounting environmental crises.

Professor Rockström is the second Pathfinder Commissioner to be given this prestigious award, considered the 'Nobel Prize for Environment', after Andy Haines, Co-Chair of the Pathfinder Commission and Professor of Environmental Change and Public Health at LSHTM, won the award in 2022.

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Dr Sarah Whitmee, assistant professor at LSHTM and lead author of the Lancet Pathfinder Commission report; Jess Beagley, policy lead at the Global Climate and Health Alliance; and Shweta Narayan, climate and health campaigner, Health Care Without Harm, emphasise the need for continued engagement by the health community to ensure that climate action is commensurate with the scale of the threat. 

The authors highlight the "health firsts" at COP28, but argue that health is not yet protected by sufficiently ambitious climate decision making.

Read the comment piece in the BMJ. 

COP28 included the first ever health themed day, a climate health ministerial, and a declaration on climate and health endorsed by over 140 countries. Representatives from the Pathfinder Initiative took part in a range of activities at COP, presenting findings from the Commission report and advocating for more ambitious action to mitigate climate change and improve health. Events featuring Pathfinder Co-Chairs, Commissioners and researchers included:

• How Ambitious Emission Reductions Can Save Lives, keynote speech delivered on Health Day by Joy Phumaphi, Co-Chair of the Pathfinder Initiative
• Solutions showcase in the green zone, presentation by Prof Tolu Oni, Pathfinder Commissioner
• Health as Entry Point for SDG / Climate Synergy: A Focus on Cities, Air Pollution and Justice, presentation given by Dr Sarah Whitmee, LSHTM
• Harnessing the health co-benefits of climate action, hosted by partners of the Pathfinder Initiative at the health pavilion
• UNFCCC side event on Accelerating a just transition for healthy people and a healthy planet, presentation by Dr Sarah Whitmee.

Following the conference, Professor Andy Haines, Co-Chair of the Pathfinder Initiative and Professor of Environmental Change and Public health at LSHTM, and Professor Liam Smeeth, LSHTM Director, commented in the BMJ on the outcomes and their implications for climate action and health. 

As leaders gather for COP28, Professor Andy Haines, Co-Chair of the Pathfinder Initiative highlights key findings from the Pathfinder Commission report and explains how governments and decision makers can implement actions that help to mitigation climate change and improve health. 

Read the comment piece (originally published on the OECD Forum Network website)

The report of the The Lancet Pathfinder Commission, part of the Pathfinder Initiative, highlights the opportunity for ambitious climate mitigation actions to improve health and save lives.

The report, published in The Lancet, shows how climate mitigation actions across different sectors have the potential to bring major benefits to health, and highlights the opportunity for global leaders to take actions that would prevent millions of premature deaths annually worldwide.

The report calls for a step-change in evidence-based action to capitalise on health gains that can be achieved through accelerating a just transition to net zero, including by rapidly phasing out of fossil fuels and replacing them with clean renewable energy, shifting to healthier more sustainable diets, and increasing physical activity by promoting active travel and public transport.

For the first time, global evidence on the health co-benefits of climate mitigation actions across sectors has been quantified and compared through a methodology developed by the Pathfinder team, led by researchers at LSHTM.

In addition to analysing the results from modelled evidence on potential health benefits from climate mitigation, the report includes examples of implemented actions with measured climate and health benefits. Further case studies and data from the Pathfinder review are showcased in a new online Climate & Health Evidence Bank, hosted by the Pathfinder Initiative.

Following the recommendations of the Commission report, the next phase of the Pathfinder Initiative will include the development of a Coalition of partners committed to the implementation and evaluation of ambitious action on climate and health.

The Commission and its report are part of the wider Pathfinder Initiative that aims to accelerate the transition to net-zero societies through providing practical, evidence-based emissions reduction pathways that also benefit human health. The initiative is funded by the Wellcome Trust with support from the Oak Foundation. Research is led by the London School of Hygiene and Tropical Medicine; partners of the first phase of work include C40 Cities, CDP, the Organization of Economic Co-operation and Development (OECD), the Sustainable Development Solutions Network (SDSN), and the Alliance for Health Policy and Systems Research. 

Read the Commission report

Read the summary

Read the news story

Explore the Evidence Bank

Find out more about the Coalition

Find out more about the Pathfinder Initiative

Find out more about the Commission

The Pathfinder Initiative will be hosting an event on the 21 November 2023, 17:30 – 19:00 (GMT) at LSHTM and online to present the findings and recommendations from the Lancet Pathfinder Commission report: Pathways to a healthy net zero future. The report provides the most comprehensive review to date of evidence on the health benefits of greenhouse gas mitigation by sector, as well as presenting evaluated examples of implemented actions. The review and case studies cover a wide range of initiatives across energy, transport, the built environment, agrifood systems, industry, sanitation and nature-based solutions, and highlight the opportunity to accelerate a just transition to net zero while bringing benefits to health and society.

At the launch event, speakers from the Pathfinder Initiative will present key findings and recommendations from the report, and highlight their significance ahead of COP28 in Dubai.

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The Pathfinder Initiative, Wellcome Trust, Global Climate and Health Alliance and World Health Organization hosted an event at the Bonn Climate Change Conference on integrating health into the Global Stocktake. Speakers discussed the links between climate and health, including losses and damages, the health co-benefits of mitigation and adaptation, and examples of policies across sectors that benefit both people and planet. 

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In an open letter published during COP27, leading experts including the Pathfinder Co-Chairs and Commissioners, call for a new Coalition to scale up and evaluate climate change actions to ensure health and equity are priorities as the world faces increasing climate risks.

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The Pathfinder Initiative hosted a side event as part of the 2022 Planetary Health Annual Meeting (PHAM), coordinated by the Planetary Health Alliance.

LSHTM researchers presented the challenges of bringing together coherent evidence on the health co-benefits of climate mitigation actions and ways forward to advance research in this area and generate evidence to inform policy and practice.

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