Private finance for nature-based flood resilience: How banks, investors and insurers can help scale nature-based approaches to flood resilience
29 September 2026 – A briefing by CISL examines how banks, investors and insurers can help scale nature-based approaches to flood resilience
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About
Flood risk is growing in the UK, increasing the need for a broader mix of prevention, protection and resilience measures. Nature-based approaches can form part of this mix, helping manage flood risk while delivering wider benefits for biodiversity, water, carbon and communities. Private finance can play a greater role in supporting these approaches, including by financing Natural Flood Management, but reaching scale will require key commercial barriers to be overcome.
This five-month CISL project explored how, through three co-creation Labs bringing together banks, investors and insurers, complemented by wider stakeholder engagement and research. Six interrelated barriers were identified. Two received particular attention: making the flood-resilience benefits of nature visible and usable in financial decision-making; and creating projects with identifiable buyers and predictable revenues that can support commercial finance.
The findings point to practical ways forward. Evidence on nature-based interventions needs to translate into financial implications that can inform lending, investment and underwriting. Projects seeking private finance need credible revenues, committed buyers, appropriate risk sharing, confidence in delivery and sufficient scale. Importantly, while revenues can come directly from flood-risk reduction, they can also come from other outcomes and activities, including biodiversity, carbon, catchment services and land-based products, potentially combining several revenue streams. Market facilitators can also help aggregate fragmented projects and connect those creating nature outcomes with buyers and finance.
The brief identifies ten potential solutions, from actions financial institutions can take today to interventions requiring multiple market actors or policy support. Private finance will not be appropriate for every project, but where projects are commercially viable and the right market and policy conditions exist, banks, investors and insurers can complement public and philanthropic funding and help nature-based flood resilience reach greater scale.
Authors
Dr Corinne S Martin, Felicity Alvey, Lucy Bruzonne, Elliot Cyriax, Trisha Mani, Dr Jonathan Middleton, Gwyn Rhodes, Annisa Sekaringtias, Eliot Whittington, Dr Nina Seega.
Key contributors
Members of the CISL-convened groups of banks, investors and insurers who attended the co-creation Labs and/or provided expert input as finance practitioners: Michael Sheren (CISL Fellow and Co-Chair of the Banking Environment Initiative), Sudip Hazra (First Sentier), Joel Challoner and Jonathan Kassian (Flood Re), William Butler and Kai Cooper (GaiaSicura), Hannah May (Hiscox), Alessandra Meraviglia (NatWest Group), Jack Longden (QBE), Angela A’Zary and James Burnett-Herkes (RenaissanceRe), Oliver Breen and Etienne Butruille (Santander), Milena Lefèvre (State Street Global Advisors), Özgür Göker (Union Bancaire Privée).
Their contributions greatly helped shape the project, but the views, findings and recommendations presented in this brief do not necessarily reflect their individual views nor those of the organisations they represent.
Acknowledgements
We wholeheartedly thank the following individuals who actively contributed expert input, feedback and suggestions, to help refine the outcomes from the Labs: Dr Stacy Vallis (Auckland University of Technology), Greta Talbot-Jones (Aviva Investors), Sara Taaffe (Church of England Pensions Board), Beth Knight (CISL Fellow), JJ Watters (LDA Design), Iraz Soyalp (Manulife), Lucy Watkinson and Takayoshi Kato (OECD), Annabel Timberlake (The Conduit and The FloodAction Coalition), Verena Kraus (UNEP FI), Dr Marc Girona (University of Cambridge), Neil Gunn (WTW and Newcastle University).
We also thank the broader membership of the CISL-convened Banking Environment Initiative, ClimateWise and Investment Leaders Groups, who helped scope and steer the project via multiple engagement opportunities.
Additional CISL contributor: Michaela Bruckner, for her wider support to the project, including helping shape the visual presentation of this brief and supporting the webinars, project webpage and social media communications.
University of Cambridge Institute for Sustainability Leadership (CISL). (2026). Private finance for nature-based flood resilience: How banks, investors and insurers can help scale nature-based approaches to flood resilience. Cambridge, UK: Cambridge Institute for Sustainability Leadership.
The opinions expressed here are those of the authors and do not represent an official position of CISL or any of its individual business partners or clients.
Copyright © 2026 University of Cambridge Institute for Sustainability Leadership (CISL).
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