Who foots the bill for climate change?

If there is one issue that has taken center stage at this year’s United Nations Climate Change Conference (COP27), it is money. Delegates, climate activists, and the rapidly increasing number of private-sector attendees are discussing who should pay for climate change, and how.

The focus on money is past due. While the annual climate talks are ultimately about cutting greenhouse-gas pollution, the transition to a net-zero economy requires massive financing, as will adapting to a world of rising average temperatures and sea levels, increasingly frequent and severe extreme weather, and all the other costly effects of burning fossil fuels.

Ever since COP15 in Copenhagen in 2009, a key figure in this debate has been “$100 billion.” That is how much the world’s advanced economies promised to provide to developing countries every year by 2020. But it was never clear whether this target referred only to public money, or whether it could include a mix of public and private flows. While most of the Global South interpreted it as a commitment of public funds, most of the Global North preferred the broader definition. If one takes the latter view, the rich world was already on track to providing $97 billion in annual climate finance flows back in 2011, according to a widely cited study from the Climate Policy Initiative.

And yet, 13 years on from the 2009 pledge, few would make the mistake of mixing public and private funding, while everyone recognizes that the global energy transition will require not billions but trillions of dollars per year. Massive amounts of private spending will need to be directed away from fossil-fuel investments and toward low-carbon infrastructure, energy, and transportation.

But that doesn’t let governments off the hook. Public funds are the lever for rechanneling private money at the necessary pace and scale. The Inflation Reduction Act, Bipartisan Infrastructure Law, and CHIPS and Science Act that the United States has recently enacted are good examples of this lever in action. The idea is that some $500 billion in government investments will encourage many hundreds of billions more in private flows.

The global picture fits a similar pattern. Since annual foreign direct investment dwarfs development aid, much of the money to cut carbon-dioxide, methane, and other greenhouse-gas pollution will come from private sources, regardless of what governments agree to do. Unlocking these funds will require what climate negotiators call “creative” solutions, which means, “We know that much more money is needed, but we can’t be the ones who provide it.”