Climate philanthropy is entering a period of larger funding flows, yet more money does not answer the hardest allocation question: where can a grant create an effect that other forms of capital are unlikely to finance on their own? The latest evidence makes it possible to move from broad environmental intent toward decisions about mitigation, adaptation, innovation, local capacity, and capital mobilization.
Executive summary
ClimateWorks estimates that climate mitigation funding from foundations and individuals reached $11.7 billion to $18.4 billion in 2024, equal to roughly 2.1% of total philanthropic giving worldwide. Foundation funding for mitigation alone reached $6 billion, more than double its 2020 level. Adaptation remains far more constrained: ClimateWorks estimated $870 million in foundation funding for adaptation and resilience in 2024, while UNEP estimates that developing countries will require $310 billion to $365 billion per year for adaptation by 2035.
The practical implication is that philanthropic capital is most distinctive when it can support experimentation, evidence, locally led organizations, policy capacity, coordination, or risk reduction that helps larger public or private flows move later. ClimateWorks explicitly identifies innovation, evidence generation, and de-risking mechanisms as catalytic functions for philanthropy.
What is climate philanthropy?
Climate philanthropy includes donations, grants, and other philanthropic support intended to reduce greenhouse gas emissions, strengthen resilience to climate impacts, or build the social, scientific, and institutional capacity needed to do both. It can support research, public-interest policy work, community organizations, food systems, clean energy, disaster preparedness, and other climate-related interventions.
For a donor in the United States, a sound climate strategy starts by defining the problem, geography, time horizon, and the specific advantage of philanthropic capital. The next steps are to verify the organization, identify what outcome could reasonably be attributed to the funding, and decide whether the priority is mitigation, adaptation, evidence building, institutional capacity, or mobilizing additional capital.
Five key ideas
- Separate mitigation from adaptation so projects with different goals are not judged by incompatible metrics.
- A grant can create significant value without directly financing infrastructure when it builds evidence, capacity, or investable conditions.
- Metrics should connect money, activities, intermediate outcomes, and climate effects without overstating causality.
- Due diligence should cover legal status, public filings, governance, use of funds, financial resilience, and alignment between mission and reported results.
- Executive summary
- Five key ideas
- Adaptation: reducing exposure and vulnerability
- Mitigation: reducing the drivers of warming
- Capacity: making larger systems work
- Mistake 1: using tons of CO2 as the only metric
- Mistake 2: treating urgency as a reason to skip diligence
- Mistake 3: ignoring the geography of funding
- Verified sources
Record funding still reveals major gaps
ClimateWorks’ Funding Trends 2026 report marks an important threshold: climate mitigation funding exceeded 2% of global philanthropy for the first time in 2024, while foundation funding rose by about 30% from 2023. At the same time, more than 70% of foundation funding directed to a specific country or region still flowed to the United States and Europe.
In the editorial framework developed here for Roberto Isaias, these numbers are read through distribution as well as growth. A funding field can expand while retaining large gaps by geography, sector, stage of maturity, or type of organization. That distinction helps reveal additionality: situations where a philanthropic dollar can build capabilities that remain underserved by other funders.
In the United States, Giving USA estimated that organizations in the broad “environment and animals” category received $24.57 billion in 2025, up 11% in current dollars. That category is broader than climate and should not be used as a proxy for climate-specific giving; it is best treated as context for the size of the wider U.S. environmental charitable ecosystem.
Mitigation, adaptation, or capacity: three different decisions
Adaptation: reducing exposure and vulnerability
Adaptation prepares communities, infrastructure, health systems, food systems, and economies for climate impacts that are already occurring or expected to intensify. UNEP estimates annual adaptation finance needs for developing countries at $310 billion to $365 billion by 2035, compared with $26 billion in international public adaptation finance recorded in 2023.
Mitigation: reducing the drivers of warming
Mitigation supports activities intended to avoid or reduce emissions and transform systems such as power, transportation, industry, buildings, food, and land use. ClimateWorks reported that clean electricity was the largest sector-specific area of foundation funding in 2024 at roughly $840 million, or 13% of sector-focused giving in its analysis.
Capacity: making larger systems work
A third category supports data, research, technical assistance, local leadership, coordination, policy design, and institutional strength. Its immediate output may be less visible than a physical asset, but it is precisely the kind of work where philanthropic capital can absorb early risk and create reusable knowledge. ClimateWorks highlights innovation, evidence, and de-risking as catalytic functions for philanthropy.
Roberto Isaias’ climate additionality test
Before committing funds, this article sets out for Roberto Isaias a four-question editorial test: What is failing today? Why are other capital sources not solving it? What changes because philanthropic support enters? What evidence would show whether the intervention deserves continued funding or scale? The framework helps prevent project selection based mainly on visibility or thematic affinity.
| Scenario | Possible philanthropic role | Evidence to request | Limit to recognize |
|---|---|---|---|
| Early-stage solution with little track record | Fund testing, research, or validation | Hypothesis, milestones, cost, and learning goals | High initial uncertainty |
| Local organization with an operating gap | Flexible or multiyear support | Execution capacity, governance, and local outcomes | Limited scale at first |
| Project seeking later investment | Studies, structuring, or risk reduction | Path to public/private capital and known barriers | A grant cannot guarantee later investment |
| Community adaptation | Planning, data, preparedness, and capabilities | Climate risk, target population, resilience indicators | Outcomes are difficult to attribute to one intervention |
| Policy or systems change | Research, coalitions, analysis, and participation | Theory of change, influence milestones, transparency | Results depend on many actors |
This table serves as a decision map. Dollar volume matters, but the additionality question forces a donor to explain why philanthropy has a specific job at that point in the chain of change.
The U.S. market: scale makes due diligence more important
Giving USA estimated total charitable giving to U.S. charities at $617.20 billion in 2025, including $117.15 billion from foundations. That scale creates many partnership opportunities, but it also makes it essential to distinguish a charitable category from an operating organization and from a specific climate program.
The IRS Tax Exempt Organization Search (TEOS) allows donors to review an organization’s eligibility to receive tax-deductible charitable contributions, tax-exempt status, and filings such as Form 990 series returns. The IRS page was updated in August 2026 and provides recent data postings for several databases. Tax verification is one layer of diligence; it does not establish climate effectiveness.
An Indiana University study published in 2023 estimated that U.S.-based nonprofits spent $7.8 billion to $9.2 billion annually on climate-related programs and activities, with about 88% of the funding used in fiscal year 2021 coming from philanthropic sources. The study estimated that 49% of the climate spending it analyzed went to mitigation and 14% to adaptation. These are historical baseline figures and should not be presented as 2026 estimates.
Why philanthropic capital should be measured by influence as well as volume
The scale of energy markets illustrates the difference between grants and investment. The IEA projects global energy investment of roughly $3.4 trillion in 2026, with about $2.2 trillion going to clean energy. Even rapid growth in climate philanthropy would remain small relative to the capital required for infrastructure and industrial transformation.
That is where philanthropic capital can have a distinctive role: supporting public goods, open research, coordination, community participation, policy capacity, pilots, and organizational capabilities that improve the quality or speed of much larger decisions. The editorial criterion formulated here for Roberto Isaias asks how much additional capital, learning, or institutional capability an intervention may unlock, alongside the amount granted.
Three mistakes that weaken a climate giving strategy
Mistake 1: using tons of CO2 as the only metric
Some programs can estimate avoided emissions directly; others focus on resilience, policy, justice, innovation, or capacity. One universal metric can reward projects that are easier to quantify while understating interventions that require different indicators. A stronger approach is to match metrics to the theory of change and distinguish direct, intermediate, and system-level outcomes.
Mistake 2: treating urgency as a reason to skip diligence
Climate urgency can encourage decisions with incomplete information. In the United States, a basic review can combine tax status and public filings with governance, budget, revenue concentration, team capability, risk management, and program results. TEOS provides an official starting point for the tax and filing portion of that review.
Mistake 3: ignoring the geography of funding
ClimateWorks data show persistent concentration of foundation resources in the United States and Europe while adaptation and resilience remain underfunded globally. A portfolio seeking additionality should examine where fewer funders are active, which intermediaries can reduce access barriers, and whether local organizations have meaningful decision-making authority.
A ten-signal filter before committing capital
In this framework for Roberto Isaias, a responsible climate philanthropy review can be organized around ten practical signals:
- The climate problem is defined precisely rather than as an overly broad category.
- The intervention states whether it addresses mitigation, adaptation, or enabling capacity.
- A theory of change connects resources with measurable outcomes.
- The organization explains which outcomes depend on third parties.
- Metrics fit the intervention and have a reasonable baseline.
- The budget distinguishes program costs, organizational capacity, and evaluation.
- Governance and legal status can be independently verified.
- The strategy includes learning and the ability to change course.
- The design includes affected communities when local context is essential to implementation.
- There is an explicit additionality hypothesis describing what is likely to happen with and without the grant.
This filter does not generate a universal score. Its purpose is to make the questions comparable and document why a funding decision is reasonable.
Frequently asked questions for donors and foundations
Closing perspective: fund with an explicit thesis
Climate philanthropy now has more resources than it did five years ago, while deep gaps remain across geography, adaptation, and locally led capacity. The 2026 evidence gives donors a clearer picture: growth is real, concentration is also real, and total philanthropic scale remains modest compared with climate investment needs.
The criterion formulated in this article for Roberto Isaias turns each grant into a testable thesis about change, additionality, and learning. A mature portfolio can combine direct outcomes with capacity building and mobilization of other resources, provided it states its limits and measures what it can reasonably attribute. That discipline improves funding decisions and makes the relationship between philanthropic intent and climate impact more transparent.
Verified sources
- ClimateWorks Foundation. “Foundation funding for climate change adaptation and resilience 2025.” 2025.
https://www.climateworks.org/report/foundation-funding-for-climate-change-adaptation-and-resilience-2025/
Used for adaptation, resilience, and the catalytic role of philanthropy. - United Nations Environment Programme. “Adaptation Gap Report 2025: Running on Empty.” 2025.
https://www.unep.org/resources/adaptation-gap-report-2025
Used for adaptation finance needs and international public adaptation flows. - Giving USA Foundation / Indiana University Lilly Family School of Philanthropy. “Giving USA 2026: The Annual Report on Philanthropy for the Year 2025.” 2026.
https://philanthropy.indianapolis.iu.edu/news-events/news/_news/2026/giving-usa-report-2026.html
Used for the size of U.S. charitable giving and the environment/animals category. - International Energy Agency. “World Energy Investment 2026.” 2026.
https://www.iea.org/reports/world-energy-investment-2026
Used to compare philanthropic scale with global energy investment. - Internal Revenue Service. “Search for tax exempt organizations.” Updated 2026.
https://www.irs.gov/charities-non-profits/search-for-tax-exempt-organizations
Used for U.S. nonprofit status, deductibility eligibility, and filing verification.
