An open call for proposals revealed valuable insights into the ecosystem of actors working on extreme heat.

Extreme heat is the deadliest climate hazard on the planet, and its toll falls hardest on the people least able to escape it — outdoor workers, informal laborers, and low-income urban residents in some of the world’s fastest-warming cities. It is not a distant risk but a present and intensifying one.

With this context in mind, ClimateWorks’ Adaptation & Resilience Fund launched its first open call for proposals in August 2025, with an initial focus on extreme heat solutions for urban communities across South Asia, Southeast Asia, and Sub-Saharan Africa. Earlier consultation and research had pointed us to two barriers standing between these communities and lasting resilience — a shortage of money and a shortage of political will and capacity. So we built the request for proposals around addressing both barriers: one track for innovative finance to unlock new capital for adaptation, and another for institutional capacity strengthening to help governments and communities put that capital to work.

We ran an open process because we believed that many of the strongest ideas for extreme heat resilience would come from outside our networks and from the frontline communities closest to the challenge. An open process helped us reach organizations we might never have found and gave us a more equitable and transparent way to see where funding could do the most good.

The response was significant: in just six weeks, we received roughly 2,000 letters of interest (LOIs) from organizations in 70 countries, representing nearly $2 billion in project funding requests. 63% of applicants were brand-new to ClimateWorks. The speed and sheer scale of the response suggest that the amount of unmet need is likely magnitudes larger. It also highlighted a deep and robust ecosystem of organizations, many working directly with frontline communities, ready to absorb funding now.

With individual attention to each LOI, we applied rigorous evaluation criteria, narrowing the set of proposals based on:

• Baseline eligibility requirements, including geographic and thematic focus
• Strategic fit and relevance
• Outcomes and impact potential
• Local leadership and partnerships
• Co-funding potential (innovative finance RFP)
• Equity & inclusion lens (institutional capacity RFP)

In all, 78 organizations submitted full proposals — 41 under innovative finance and 37 under institutional capacity. To learn more about the selected organizations, read our companion announcement. 

What we learned about the field of extreme heat resilience 

The response to the open call was overwhelming — and revealing. We designed the LOI as a lighter first step ahead of the full application, which drew a broader range of organizations — and gave us a rare, unfiltered view of who is working on extreme heat resilience across the Global South and what they need to succeed. We’re sharing key lessons from this experience to make this work more visible to funders and to demonstrate that the vast opportunity for impact is already within reach. Here’s what we learned: 

There is already robust capacity and expertise for addressing the rising threat of extreme heat.

Communities, municipalities, and civil society organizations across countries in the Global South already have working solutions to extreme heat. In particular, the nearly 2,000 LOIs we received highlighted significant momentum at the subnational level, where actors across cities, communities, and civil society are treating heat as an urgent, defining threat — and already building the capacity to meet it.

However, efforts to address extreme heat face barriers to funding and are often under-prioritized in national action plans.

We received proposals that strongly emphasized city-level financing as a critical lever, identifying two entry points: strengthening municipal capacity and expanding the financing mechanisms available to cities. However, these pathways largely remain limited and difficult to use, and require institutional capacity, legal frameworks, and credit ratings that most municipalities don’t yet have — even as development banks have worked to expand access through bonds, loans, and public-priviate partnerships. And although national plans have the potential to unlock finance flows at the subnational and local levels, many still treat extreme heat as an afterthought, even as demand on the ground surges. Of the 67 developing-country National Adaptation Plans submitted to the UNFCCC as of September 2025, only 27 name heatwaves as a climate hazard — well behind droughts (63) and floods (60) — and extreme heat rarely appears as a priority in its own right.

The scale of demand is inseparable from a historic retreat in public funding.

The volume of applications we received didn’t emerge in a vacuum. As bilateral and multilateral donors pull back — amid an unprecedented contraction in official development assistance — frontline organizations are searching for new sources of support, surfacing a structural shortfall in how adaptation gets financed.

Capacity and demand exist across all our priority geographies, but the shape of extreme heat action varies by region.

Our call focused on urban areas in Sub-Saharan Africa, Southeast Asia, and South Asia that are vulnerable to extreme heat. We saw a strong response from all regions, with more than half of the proposals coming from Sub-Saharan Africa, demonstrating both the diversity of projects and actors already working on this issue and the significant need for greater investment in the region (Figure 2). Many of the proposals from Sub-Saharan Africa reflected grassroots energy and strong community-based leadership, with promising local models positioned to develop and grow with further investment. Proposals from South Asia often built on existing government buy-in and established Heat Action Plans, with organizations that had already completed pilots and were positioned to scale. 

The proposals revealed the types of extreme heat solutions gaining traction.

The largest share of proposals centered on Heat Action Plans, community response planning, and framework development — the scaffolding cities need to move from ad hoc response to long-term resilience (Figure 3). Also rising to the top was governance and policy integration: most proposals included a government engagement component, aiming to situate heat response within departmental budgets, staffing, and mandates rather than leaving it as a separate line item. 

The institutional capacity building LOIs also had a strong secondary focus on community engagement and civil society capacity — advancing heat solutions that incorporate meaningful input from the people they’re meant to protect. Additionally, some form of equity considerations appeared in almost 95% of LOIs submitted, and more than half proposed gender-specific solutions or applied a gender lens.

Finally, the proposals received underscore that extreme heat is a multidisciplinary issue that must be addressed accordingly. Many of the most compelling proposals recommended cross-cutting, cross-sectoral solutions — and consistently linked heat to interconnected issues like public health, livelihoods and economic resilience, labor justice, informal settlements, and displacement and migration, among many other sectors, themes, and disciplines.

Blended finance and insurance are commonly proposed mechanisms to unlock action on heat.

Notably, insurance-related proposals reflected growing momentum for scaling parametric and index-based products as risk-transfer tools for protecting livelihoods, particularly for low-income communities and informal workers without a financial safety net when extreme heat threatens their jobs and incomes (Figure 4). 

The field is ready. Now the funding has to follow. 

The response made one thing clear: extreme heat resilience isn’t an idea waiting to be discovered — the work is already underway, led by organizations that know what their communities need. What’s missing isn’t ideas, ambition, or the capacity to deliver — it’s funding.

Now is a critical time to mobilize funding for extreme heat resilience and build on the momentum and solutions that already exist. We are calling on philanthropic foundations, bilateral and multilateral donors, development finance institutions, and country-level financing mechanisms to move beyond fragmented, one-off grants toward the sustained, flexible, multi-year commitments that let local organizations build resilience that lasts. 

The solutions exist. The capacity is proven. What remains is to fund it at the scale demanded by the crisis.