On the Gates climate memo

There are a lot of things I agree with in Bill Gates’ new memo on climate change. The recent cutbacks on international spending on vaccination, malaria control, feeding the hungry, and poverty alleviation by many of the richest countries (driven in part by a desire for more military spending) is a catastrophe that will cost thousands if not millions of lives. Adaptation is a critically important part of addressing climate change, and a world with more prosperity and less inequality is one where we can better deal with the impacts of climate change – at least up to a point.

But in other areas I feel that it needlessly sets up a conflict between laudable goals: we can both mitigate emissions and alleviate poverty, disease, and hunger. While there are some tradeoffs it is more a question of policy priority than a zero sum game. Similarly, I feel that Gates is a bit too cavalier in his treatment of climate risk.

Given the strong reactions to Gates’ memo both on the left and the right, I thought it would be helpful to provide a more measured reaction and critique, and give some thoughts how to move forward to – as Gates suggests – have the most positive impact on the world.

A zero sum game?

Bill Gates – through his philanthropic work with the Gates Foundation – has done more than almost anyone else on the planet to meaningfully improve the lives of the world’s poorest. The Gates Foundation was the founding funder of Gavi which helped expand vaccination in the global south and drive down prices. They did key work to help eradicate polio, combat HIV, TB and malaria, deliver sanitation and clean drinking water, and worked to raise smallholder farmer yields and income through access to agricultural technology.

The recent gutting of USAID – and smaller reductions in aid spending by other countries – is a humanitarian catastrophe and threatens to undo much of the work that the Gates Foundation supported over the past few decades. I can see why, in light of these urgent needs, he is suggesting that resources to combat climate change be repurposed toward dealing with poverty, hunger, and disease.

But this assumes that funding for climate and development (to use a term to encompass help improve the lives of the world’s poorest) are inherently zero sum. And here I think that, for the most part, Gates errs in his analysis – for a few reasons:

First, the vast majority of spending on climate mitigation worldwide is not in low income countries, and there is little reason to assume that cutting it would free up resources for development aid. The world spent more than two trillion on clean energy technologies (albeit somewhat expansively defined) in 2024, but the overwhelming majority of this was spent by middle- and high-income countries (e.g. China, the US, the EU, the UK, India, Japan, etc.) to build domestic clean energy, build transmission, buy electric vehicles, electrify heating, etc.

The idea that spending less on domestic mitigation would create more budget space for international development is fundamentally misguided. Its hard to imagine that the Trump administration will revitalize development spending based on savings from cutting domestic green energy subsidies. Both development aid and climate mitigation spending represent relatively small shares of GDP in higher income countries, and there is space for policy to be able to prioritize spending on both without trading them off against each other. It is much more likely that any reduction in mitigation spending will be repurposed for other domestic priorities – leaving the poorest and most vulnerable parts of the world even worse off.

Second, there are a number of ways that technologies can accomplish goals of climate mitigation and development simultaneously. Solar and storage for electrification of more remote areas, clean cook stoves to reduce deforestation, technologies to reduce both outdoor and indoor air pollution that kills millions per year globally are a few examples.

That being said, we should take a hard look at international spending priorities for programs in the poorest countries which, in turn, are the least responsible for global emissions today. Here adaptation should be strongly prioritized, and restrictions around finance for some fossil fuels (e.g. natural gas development in Sub-Saharan Africa) that could help support greater clean energy deployment should be reconsidered. We should generally spend more than we are today on adaptation and development (though the two are strongly related), and mitigation should be less of a priority in low income countries.

Richer countries should be the ones taking the lead on emissions reductions, and paying a (green) premium that will help drive down the costs of clean energy technologies so that they can be cost effectively adopted by lower income countries. Indeed, thats largely been the story of our successes here to date, with countries like China, India, and Brazil adopting ambitious net-zero goals in part because they see the cost of meeting them as modest and not trading off against their development priorities.

Third, the idea that we should “spend less” on climate adaptation is a dangerous misunderstanding of the problem. There is no world where we don’t spend money dealing with climate impacts. Rather, our choice is between spending money now to, e.g., build a seawall, or spend money later to rebuild the city after it floods. Our choice here should be guided by the fact that adaptation in advance is cheaper than adaptation after the disaster. In other words, spending money today on adaptation is the cheaper option that will better promote health and welfare of the world’s poorest citizens.

Hedging against climate risks

In his memo, Bill Gates highlights the progress we’ve made on climate change to-date, noting that:

Ten years ago, the International Energy Agency predicted that by 2040, the world would be emitting 50 billion tons of carbon dioxide every year. Now, just a decade later, the IEA’s forecast has dropped to 30 billion, and it’s projecting that 2050 emissions will be even lower.

Read that again: In the past 10 years, we’ve cut projected emissions by more than 40 percent.

This progress is not part of the prevailing view of climate change, but it should be. What made it possible is that the Green Premium—the cost difference between clean and dirty ways of doing something—reached zero or became negative for solar, wind, power storage, and electric vehicles. By and large, they are just as cheap as, or even cheaper than, their fossil fuel counterparts.

Gates is right that cheap clean energy represents a remarkable success story, and is one of the reasons why projections of future warming have fallen from around 3.5C a decade ago to around 2.7C today.

Historical global mean surface temperatures through 2023, alongside the range of SSP temperature outcomes in the IPCC AR6 (grey) and those consistent with current policies and commitments (blue). Figure from Hausfather 2025.

But focusing on these precise temperature outcomes in 2100 is problematically reductionist. Our emissions are just one of three factors that will determine the future warming of the planet (and we should remember that current policies represent neither a ceiling nor a floor on current emissions, particularly at a time when some governments are actively rolling them back).

Even if we knew future emissions precisely, the warming in 2100 remains highly uncertain. It depends both on the sensitivity of the climate to our increased atmospheric greenhouse gas concentrations – the response of various climate feedbacks like clouds and surface reflectivity – and how the carbon cycle responds to both our emissions and the changing climate.

Due to the combination of these uncertainties, its possible that we think we are heading for 2.7C warming and actually end up at 3.7C (or even 4C+) if we roll 6s on the proverbial climate dice. And we won’t know precisely how sensitive the climate is (despite some recent progress) until its too late to avoid where we are headed.

This means that we should think of mitigation less as targeting (or avoiding) a particular certain outcome, and more as hedging against risk. We should do more mitigation – all things considered – than if we had certainty in the climate response because of the high damages associated with less-likely but still quite possible tail risks. Or as the late climate economist Marty Weitzman memorably put it, when it comes to climate change “the sting is in the tail”.

Gates is right to note that climate change “will not lead to humanity’s demise”, but I’d suggest that this represents a bit of a straw man. Outside a fringe community of climate doomers there are few who think that climate change could realistically threaten the extinction of the human race (though some folks need to be a bit cautious about throwing around the term “existential threat” willy nilly). As the climate scientist Steven Schneider was fond of saying, for climate change “the end of the world and good for you are the two lowest probability outcomes”.

But not being an existential threat does not tell us all that much, as almost nothing aside from a planet-killing astroid or (possibly) an all-out global thermonuclear war rises to that highest of bars. Every other problem humanity deals with – war, violence, famine, poverty – is not existential but is still critically important. This is more or less Gates’ point, that climate should be treated as one of many problems that we need to solve rather than an all-encompassing ur-problem. But by and large the majority of people and policymakers have been treating it as just that.

Green premiums and brown costs

Gates posits that society can best address climate change by working to reduce the “green premium” associated with clean energy technologies (this was more or less the central thesis of his 2021 book How to Avoid a Climate Disaster.

The idea of the green premium is compelling. As noted earlier, a lot of the progress that society has made on reducing emissions over the past 15 years has come on the back of near-miraculously rapid declines in the cost of clean energy technologies. Cheaper clean energy in turn enables more ambitious policy adoption, as the costs of getting to net-zero emissions turn from astronomical to manageable.

But I’d suggest that it is somewhat incomplete, at least in its more straightforward interpretation. There is an idea that innovation and markets alone will necessarily solve the problem in the absence of policy interventions; that if we can just make clean energy cheap enough the world will sufficiently decarbonize to avoid potentially catastrophic impacts from climate change.

This may be the case, but it may not. Innovation cuts both ways – the success of hydraulic fracturing and horizontal drilling technology has drastically reduced the cost of natural gas and oil production. There are lots of resources going into producing fossil fuels more cheaply, and while I’m hopeful that the cost of solar, batteries, wind, nuclear, geothermal, and other clean energy technologies will fall faster there is no law of physics that says that it will inevitably be cheaper.

Hoping that clean energy will be absolutely cheaper than fossil fuels at a scale needed to decarbonize our energy system is a gamble – and one with loaded dice. There are real costs associated with fossil fuel use: from air pollution, from climate change, from local environmental damage. These are currently borne by the public and not by the companies producing fossil fuels. As long as the costs remain socialized while the benefits are privatized, the market alone will not lead to the optimal level of deployment of clean energy technologies.

This is where policy comes in: we either need to include the “brown costs” of fossil fuels in their market price (e.g. a carbon tax, something that has been not very politically palatable to date) or be willing to pay some ongoing green premium in cases where clean energy remains more expensive to account for the real costs of climate and pollution.

Policy also plays a key role in technology. The rapid and amazing drop in the price of solar energy over the last few decades has been driven to a large extent by government support of the technology. The free market may have done this by itself, but it would have likely taken many decades longer.

I don’t think Gates would necessarily disagree with any of this, but its an important rejoinder for those who assume that innovation alone is sufficient to address the problem.

The death of nuance

The reception of the Gates memo was an unfortunate reflection of our extremely polarized politics. Some climate advocates dismissed it as denialism or the second coming of Bjorn Lomborg, while those on the right (including President Trump) portrayed it as proof that the science was wrong and climate change was actually a hoax.

Gates tried at length and upfront to make his position clear that climate is a big problem and his interest is on near-term prioritization of resources, but most interpreted the memo through their ideological priors (many likely without actually reading it).

To be clear: Climate change is a very important problem. It needs to be solved, along with other problems like malaria and malnutrition. Every tenth of a degree of heating that we prevent is hugely beneficial because a stable climate makes it easier to improve people’s lives.

Our inability to have nuanced discussions about these matters is detrimental to the broader societal discussion about serious issues like climate change. The portrayal of climate as an all or nothing problem coupled with the US’s thermostatic politics (where control of government commonly switches between parties) is a recipe for a lack of clear long term action on climate or any other big societal problem that gets caught up in the politicized culture wars. While I don’t know how to change society to make science less politicized and to center the debate around the best solutions rather than the physical reality of the problem, a change is sorely needed.

Balancing future and present harms

Ultimately Gates’ memo is making that case that we need to set a higher priority on helping the world’s most vulnerable in a time when aid to them is being cut. I broadly agree. But I think that deprioritizing mitigation spending is not a very effective way to accomplish that goal, outside of the relatively modest amount of money the world spends today on mitigation in the least developed countries.

When there is an option to spend money already going to these countries in a way that provides the greatest benefits for the population even if it does not reduce (or even increases) emissions, we should probably do it. But the vast majority of the resources we spend on decarbonization today in middle and upper income countries will not magically be repurposed for international development aid if we deprioritize climate change as an issue. And deprioritizing climate change as an issue risks substituting near-term benefits for long term harms that are nearly impossible to reverse.

A world of unabated climate change will impact the poor most severely. Addressing it requires two strategies in tandem: prioritizing development and poverty alleviation to build adaptive capacity (and human flourishing), and reducing emissions rapidly in middle and upper-income countries to mitigate future climate impacts and drive down the cost of clean energy technologies so they can be more readily adopted by low income countries. Perhaps I’m unduly optimistic, but I think that society should be able to do both.