The OWID Brief: How much development aid is spent on climate change?

1. Key Themes

Theme: Climate finance is a large and growing share of development aid, but the labeling is murky

Roughly one-fifth of all aid, and one-third of allocable bilateral aid, is climate-related

Using RioMarkers tags, OWID built a dataset that finally answers a question that lacked good data for years.

"The headline result is that, in 2024, around one-fifth of development aid was climate-related. For allocable bilateral aid — that is, aid given from one country to another for specific projects — the share was one-third."

The split between mitigation, adaptation, and dual-purpose projects is roughly even

"Some of that aid is given to climate mitigation projects, which aim to reduce greenhouse gas emissions. Some is given to adaptation: ways of dealing with the impacts of climate change. And just as much is given to projects that do both."

Whether climate aid crowds out traditional aid is hard to measure

Many projects are traditional aid with a thin climate overlay, which complicates any claim about displacement.

"Take the building of a hospital in Tanzania; its main objective is to provide healthcare and save lives. But it's also tagged as a climate-related project because it was built with energy efficiency in mind."

Theme: The clean-power transition is a story of renewables growth and nuclear stagnation

Renewables now generate more than three times as much electricity as nuclear

In 2000 the two had similar shares of global electricity. Since then their paths have diverged sharply.

"In 2025, renewables made up more than three times as much: 34% compared to 9%."

Nuclear's decline is a share story, not an absolute one

Nuclear output is flat while total electricity demand grew.

"The total amount of electricity produced by nuclear plants is about the same as it was two decades ago. But because the world produces much more electricity overall, its share of the electricity mix has declined."

Fossil fuels remain dominant despite the transition

The chart description shows fossil fuels declining but still holding the largest share, at roughly 57%.

"Labels show roughly 57 percent fossil fuels, 34 percent renewables, and 9 percent nuclear in the latest year."

Theme: Remittances are a larger lifeline than aid and investment, and are geographically concentrated

Remittances outweigh aid and foreign investment combined

"In 2024, migrants sent an estimated $695 billion to low- and middle-income countries. That's more than those countries received in aid and foreign investment combined."

Source-country concentration creates risk

"For 51 countries, more than half of their remittances come from a single country. In Mexico's case, nearly 97% come from the US."

Dependence is riskiest where remittances are large relative to the economy

"Remittances from France equal 18% of national income in the Comoros, and money sent from the Gulf states is worth more than 5% of national income in Nepal, Pakistan, Jordan, and Egypt."

Theme: AI is producing research output faster than humans can verify it

OpenAI's math release outpaced human comprehension

"In early October, OpenAI released 372 results on long-standing open problems in math and computer science, all produced by one of its internal AI models."

The claimed breakthroughs are significant but unverified

"Aaronson writes that almost none of the proofs have been understood by anyone yet. His wife described the 'unique games' paper as so badly written that she couldn't read it without help from AI."

Theme: Mental health interventions need to be timed to age of onset

Most disorders begin early, but timing varies by condition

"Around two-thirds of people who will ever experience a mental health disorder do so by the age of 25."

Different conditions peak at different ages

"Social anxiety, for example, tends to first develop in childhood, and almost 80% of those who will experience it at some point in their lives do so before the age of 18."

"Some tend to peak around age 20, but will often still develop later in adulthood. This includes substance use (alcohol and cannabis) disorders and schizophrenia, which commonly develop in someone's twenties."

2. Contrarian Perspectives

Climate aid may be a relabeling exercise rather than new money

The conventional narrative celebrates rising climate finance, but OWID flags that headline numbers may overstate real additionality.

"Concerns about the displacement of traditional projects seem real, but so too are concerns that commitments to climate finance are often met through a relabeling exercise."

Evidence: the Tanzanian hospital is tagged as climate-related for its energy efficiency, yet OWID notes: "Would that hospital have been built in a world without climate change? Probably."

The nuclear "decline" is a growth-denominator problem, not a collapse in output

Nuclear is often described as shrinking, but absolute generation is flat. The real issue is that the world failed to build more of it as demand rose.

"A lack of enthusiasm for nuclear means it's playing a shrinking role in the global mix."

Remittances, not aid, are the dominant external financial flow, yet policy attention is concentrated on aid

The $695 billion figure exceeds aid and foreign investment combined, suggesting that policy levers around migration and remittance corridors may matter more for development than aid budgets.

"That's more than those countries received in aid and foreign investment combined."

3. Companies Identified

OpenAI

• Description: AI research lab.
• Why mentioned: Released a large batch of AI-generated results on open math and computer science problems.
• Quote: "OpenAI released 372 results on long-standing open problems in math and computer science, all produced by one of its internal AI models."

Ember

• Description: Energy think tank and data provider.
• Why mentioned: Source of the global electricity mix data.
• Quote: "Source: Ember; EI — Statistical Review of World Energy (2026)."

Energy Institute (EI) — Statistical Review of World Energy

• Description: Publisher of the annual energy statistics benchmark.
• Why mentioned: Co-source of the electricity generation chart.
• Quote: "Source: Ember; EI — Statistical Review of World Energy (2026)."

World Bank

• Description: International development lender and data provider.
• Why mentioned: Previously published bilateral remittance data, but shut the project down.
• Quote: "The World Bank's last version of this data was for 2021, and that project has since been shut down."

Center for Global Development

• Description: Think tank focused on global development policy.
• Why mentioned: Researchers there rebuilt the bilateral remittance dataset for 2024.
• Quote: "Sam Huckstep and Michael Clemens at the Center for Global Development have estimated how much money migrants sent home in 2024, for each pair of sending and receiving countries."

4. People Identified

Scott Aaronson

• Description: Computer scientist and blogger.
• Why mentioned: Wrote a widely read analysis of OpenAI's math results.
• Quote: "The computer scientist Scott Aaronson wrote this blog post the next day, and I thought it was a really good take on this release of very significant, if very hard to understand, papers."

Dana Moshkovitz

• Description: Complexity theorist, wife of Scott Aaronson.
• Why mentioned: Has long worked on the unique games conjecture and reviewed the AI-produced proof.
• Quote: "Aaronson's wife, Dana Moshkovitz, is a complexity theorist and has been trying to prove the conjecture for many years."

Sam Huckstep and Michael Clemens

• Description: Researchers at the Center for Global Development.
• Why mentioned: Produced updated 2024 bilateral remittance estimates after the World Bank project ended.
• Quote: "Huckstep and Clemens used the same method to bring the numbers forward."

Hannah (Ritchie) and Pablo

• Description: OWID researchers and authors.
• Why mentioned: Authors of the climate-related aid analysis and, for Hannah, the mental health onset article.
• Quote: "Read Hannah and Pablo's article"

5. Operating Insights

Build the dataset when none exists

OWID created a new climate-aid dataset from existing tags rather than waiting for authoritative data. Similarly, CGD rebuilt remittance data after the World Bank abandoned it. Gaps left by incumbents are opportunities.

"For a long time, we didn't have good data to answer this basic question. But using tags from the RioMarkers database, we've constructed a dataset on how much aid is spent on climate change."

Treat concentration as a risk metric

Whether in remittance corridors or revenue sources, dependence on a single counterpart is a vulnerability, and it is worst when the flow is large relative to the base.

"The authors say this reliance is riskiest where remittances are big relative to the economy that receives them."

Time interventions to when users are most vulnerable

Onset-age data shows that support is most effective when matched to the life stage where risk peaks.

"Knowing the age at which people might be particularly vulnerable to the onset of a mental health condition is important. It helps societies offer support at the right time to make a difference."

6. Overlooked Insights

Verification, not generation, may become the bottleneck for AI-driven science

The AI-produced proofs include claimed speedups for long-stuck problems, yet verification lags badly.

"Two other papers claim to have sped up the method for problems that researchers had been stuck on for decades (multiplying large numbers and breaking a signal down into the frequencies it's made of)."

Low-cost aid increases could have outsized impact

A brief mention suggests marginal increases in giving are highly leveraged given how little most countries spend.

"Most countries spend less than 1% of their national income on foreign aid; even small increases could make a big difference."