How cities are turning to nature-based solutions

These are having a positive impact on the top health concerns identified by subnational governments (heart-related illnesses, vector-borne infections and diseases, and respiratory diseases), especially for the most at risk in society (identified as the elderly, vulnerable health groups and children).

However, there is a substantial funding gap for realising climate adaptation projects, with nearly half of cities, states and regions (46 per cent) reporting that budget constraints hinder them. In 2025, subnational governments sought $33.51bn for adaptation projects, with $2.85bn needed just for nature-related projects.

“Climate change and nature loss are not separate issues,” said Katie Walsh, CDP global director for cities, states and regions. “As climate impacts intensify, damaged and degraded ecosystems leave communities ever more vulnerable. Cities, states and regions increasingly recognise that protecting nature and tackling climate change are two sides of the same coin. 

“Transparent environmental data can help partners identify where that investment is needed and direct capital towards projects capable of delivering solutions for building resilient communities”

“Our data shows that this is increasingly moving from ambition to action, with nature-based solutions becoming core adaptation measures rather than optional environmental initiatives. As serious climate action becomes mainstream for cities, states and regions, unlocking the funding they sorely need to achieve this, is an urgent priority for investors and governments. 

“Transparent environmental data can help partners identify where that investment is needed and direct capital towards projects capable of delivering solutions for building resilient communities.”

Examples of nature-based solutions by subnational governments: 

• The City of Porto Alegre’s (Brazil) Nova Ipiranga Urban Consortium Operation is a $332m plan to restore the Arroio Dilúvio brook across 1,624 hectares and 16 neighbourhoods, combining sanitation, drainage, green-blue infrastructure, public space, mobility, and social housing improvements. The city is also seeking funding for “Rain Gardens”, using existing public infrastructure to capture and manage stormwater during periods of intense rainfall
• The water-scarce province of KwaZulu-Natal (South Africa) has a Transformative River Management Programme to rehabilitate polluted and flood-prone river corridors, improving water security and community resilience against floods and droughts
• The Auckland Council (New Zealand) is expanding its urban forest canopy across 16 local boards and planting 11,000 street trees
• The City of Boulder’s (USA) Cool Boulder campaign saw more than 70 community volunteers collecting temperature and humidity data on one of the year’s hottest days, producing heat maps that guide green infrastructure strategies to cool the city, build climate resilience, and reduce the unhealthy effects of extreme heat. 

Maryke van Staden, director of the Carbon Climate Centre at ICLEI, the network of local and regional governments which partners with CDP on the CDP-ICLEI Track portal, said: “There is tremendous potential for synergy between climate action and nature-based solutions. With tighter public budgets, local and other subnational state governments need to be more efficient. They have an opportunity to design and implement win-win approaches for people and place, by exploring integrated climate action – resilience, adaptation and mitigation – in combination with nature, also to protect biodiversity. Green spaces help to cool cites. Green roofs and walls can insulate buildings. The range of actions is vast.

“Reporting to CDP-ICLEI Track, our global reporting platform tracking subnational climate action and investment needs, enables these analyses. We urge decision-makers at all levels of government and in the private sector to better understand options for positive impact by exploring this analysis.

“Stay the course and accelerate the tempo! We are here to support you with this essential work.”