As progressives have coalesced around the Green New Deal, its proponents say that its ambitious targets for reducing greenhouse gas emissions would, if adopted, protect the Earth from catastrophic global warming. An article in the Nation called the Green New Deal “our best hope for saving the planet,” because it would “confront climate change on the scale that this crisis demands.” Some commentators present averting climate disaster as a kind of national race against a foreign enemy, like a Manhattan Project for the whole economy. “In the 1960s, the U.S. pointed the full power of its military-technological industry at going to the moon,” wrote the Atlantic’s Robinson Meyer. Rep. Alexandria “Ocasio-Cortez wants to do the same thing, except to save the planet.”

Outlook • Perspective Illustration by Federica Bordoni Ben Adler is senior editor at City & State NY. He assigns and edits news, feature and opinion articles. Prior to joining City & State, Ben covered national and international politics and policy with specialties in the environment, cities, transportation, civil rights and housing. He was a reporter for Politico, The Nation, and Grist and an editor at Newsweek and Reuters. Follow @badler

You never would know from these encomiums that the Green New Deal cannot stave off calamity by keeping the planet from warming 2 degrees Celsius above preindustrial temperatures, the threshold endorsed by most scientists. That’s because, like the 1930s New Deal and the 1960s space program, the Green New Deal is focused on the United States.

Yet the United States is currently responsible for only 15 percent of global greenhouse gas emissions, and that share is declining as pollution from the developing world rises. So while radical cuts to U.S. emissions — which are the largest per capita after a few Persian Gulf nations and Australia — are necessary, they’re insufficient. Every other rich country also needs to make similar cuts, immediately. The developed nations with large emissions (Saudi Arabia, Canada, Germany, Japan, Britain and others) can afford their own Green New Deals; perhaps they can be persuaded to do their parts, if we do.

But developing nations — such as India, Pakistan, Ecuador and Malaysia — aren’t going to unilaterally constrain their own economies. If carbon-based energy sources help them compete in the global marketplace, that’s what they’ll use — unless, economists say, they get financial help to develop sustainably, with industrialization powered by renewable energy instead of oil, gas and coal. And there’s only one place they can get that help: from wealthy countries like ours. Giving them cash needs to be part of any Green New Deal.

Conservative critics, pointing to inflated estimates of its possible costs, have said the Green New Deal is too big. But when it comes to saving the planet, it’s not nearly big enough.

President Barack Obama knew the United States couldn’t confront climate change single-handedly. So, in the run-up to the 2015 climate negotiations in Paris, he sought commitments from China and Brazil, two previously recalcitrant large emitters, to work alongside the United States. The pledges were modest: Brazil would double its share of electricity from non-hydro renewables to 20 percent by 2030 and reforest 30 million acres of the Amazon, while China would begin lowering its emissions and reach a 20 percent renewable-energy portfolio by 2030. These promises were widely hailed as breakthroughs, because these countries had previously argued that they were too poor to sacrifice their short-term economic objectives. Obama did this without applying any pressure except private diplomacy.

The next president could go further and tell allies such as Germany, Japan and Canada that their status as major trading partners protected by the U.S. security umbrella is now contingent upon their making steep emissions cuts. Obama couldn’t do anything like this because American emissions cuts were so modest at the time; other rich countries generally have lower per capita emissions than the United States does, and they already were offering plans of at least comparable ambition to ours. But if Congress passed a Green New Deal, America would have a stronger hand to play. (Of course, Washington has many strategic concerns and may not wish to prioritize climate over other diplomatic, economic or security issues. But scientific studies suggest that unchecked climate change will cost more in economic losses and security challenges than the cost of preventing it.)

In the poorest developing countries, where many people live without electricity or other basic necessities, it is unrealistic to expect emissions to drop from their already low rates in the next decade. Some of these countries, including India, Indonesia and the Philippines, are very populous, and their industrialization could cause emissions to skyrocket. To prevent that, they’ll need to pursue policies that will allow them to develop with a much lower emissions trajectory than what North America, Europe and East Asia followed, and they’ll need to offset emissions with measures to absorb carbon pollution, such as reforestation. But they mostly lack the wealth — and in some cases, the technological capacity — to develop low-carbon electricity generation and transportation on the scale needed.

That’s where the United States and its wealthy allies come in. Poorer countries can be induced with subsidies to make bolder commitments. We know because they’ve said so. In the Paris negotiations, developing nations were explicitly open to making more ambitious commitments if developed countries contributed to making them happen. Some nations, including Mexico, went so far as to offer “conditional pledges” that they would make steeper emissions cuts if properly compensated. At the time, Ajay Mathur, the director of India’s Bureau of Energy Efficiency, said his country would “absolutely” transition more aggressively to renewables if it received sufficient international assistance.

Rich countries industrialized with fossil fuels, developing industries powered by coal, delivering fossil-fuel-based electricity and heat to homes, and building transportation systems that run on the internal-combustion engine. In following this path, these countries chewed through most of the planet’s “carbon budget” — the amount of greenhouse gas that could be spewed until global temperatures warmed by 2 degrees Celsius, which has long been the generally accepted threshold that climate scientists urge us to stay below to avoid problems like widespread drought-induced famine and the inundation of large, low-lying cities. The United States has contributed about 26 percent of the world’s cumulative emissions, and the 28 nations of the European Union are responsible for only slightly less. More recent estimates suggest that disastrous effects will kick in at 1.5 degrees Celsius, meaning the carbon budget is already spent; if Americans had been restricted to emitting a proportional share of a global carbon budget that capped warming at 1.5 degrees, we would have blown through that limit in 1944.

So rich countries have to make aggressive emissions-reduction plans of their own and generously fund “climate finance.” Except for one sentence vaguely urging “international exchange of technology, expertise, products, funding, and services . . . to help other countries,” the Green New Deal congressional resolution fails to consider our obligations to other nations.

Climate finance means foreign aid for three main purposes. The first is mitigation: subsidies for renewable-energy deployment and storage, electrical-grid modernization, and other means of reducing emissions. (Washington could, for instance, offer India cash to build wind and solar power plants and improve the efficiency of its grid.) The second is adaptation, which means preparing societies and their infrastructure for the effects of climate change, such as building flood walls to hold back higher sea levels or retrofitting buildings to withstand more severe heat waves. (In Bangladesh, for example, sea level rise might displace 18 million people by 2050, so the country needs help raising homes and moving people to higher ground.) The last, and most controversial, is coverage for loss or damage: compensation for people whose homes become uninhabitable or whose livelihoods are destroyed by climate change.

These wealth transfers are part of what activists call “climate justice,” which also includes providing support to marginalized communities that are disproportionately affected by climate change in rich countries. (Think of residents in storm-damaged low-lying neighborhoods like New Orleans’s Lower Ninth Ward or waterfront public-housing projects in New York City.) The U.N. Environment Program estimated in 2016 that the cost of adapting to climate change in developing countries could reach $300 billion per year in 2030 and $500 billion in 2050. Some of that will be funded by poorer nations — their private sectors and regional institutions. But developed nations, nongovernmental organizations and international lending institutions such as the World Bank will need to kick in a significant portion. Some projects, such as a climate-resilient housing development, commercial building or electricity grid, could be supported through private investment. Even then, governments of rich countries may have to offer loan guarantees, as the United States did for domestic clean-energy projects through the 2009 stimulus package. American banks might be reluctant to back a wind farm in sub-Saharan Africa but more willing to do so if a government limits their risk. “Most mitigation work generates money,” says Jesse Young, senior adviser for climate and energy at Oxfam America. “The reason big banks like JPMorgan aren’t lending in [countries like] Burkina Faso is because there isn’t enough financial infrastructure that allows them to take on risk to lend in those countries. So some of this is creating those tools.”

Paltry climate finance was a major obstacle in the Paris negotiations in 2015. In the end, the total global commitments made there to lowering emissions would put the world on a path toward warming by roughly 3 degrees Celsius — above the 2 degree threshold. If the United States, Europe, China, Japan and others don’t provide the funds, the world won’t get the emissions-reduction commitments it needs.

Last year, at a climate summit in Poland, India reiterated its openness to doing more if it were adequately subsidized, and an organization of the 47 least-developed nations echoed that plea. “Increasing your ambition on your [climate action] plan alone will not be the right answer. There needs to be ambition in terms of increasing financial support,” said Gebru Jember Endalew, the Ethiopian chair of the group.

In 2009, then-Secretary of State Hillary Clinton offered a bold new climate finance commitment to jump-start climate talks that were grinding to a halt in Copenhagen. She announced that developed nations would raise $100 billion per year from public and private sources by 2020. The figure in 2016 had passed $70 billion, according to a U.N. estimate. (Some nations argue that the real number is much lower. The Trump administration stopped submitting data about this to the United Nations, but the organization estimated that the U.S. government gave nearly $2 billion in climate finance in 2016.) If wealthy countries reach Clinton’s 2020 target, future negotiations may yield a higher annual figure. But the Trump administration is undercutting that possible growth by holding back two-thirds of the $3 billion Obama promised for the Green Climate Fund. “The lack of real money coming through is really undermining trust in the negotiations,” an advocate for developing nations said at an international conclave in Bangkok last fall.

Still, even $100 billion will not be nearly enough. It was “a made-up number” to prevent the collapse of the Copenhagen negotiations, according to Leonardo Martinez-Diaz, global director of the Sustainable Finance Center at the World Resources Institute. “It wasn’t based on an analysis of what was needed to meet the challenge, necessarily.” Nobody knows how big the ultimate U.S. number will need to be; it depends on how many rich countries pitch in, and how much they give, and how much help poorer countries need to modernize in eco-friendly ways. The World Economic Forum produced a study in 2013 that said to stay below 2 degrees of warming, by 2030 the global economy needs to give a “green” makeover to the $5 trillion per year spent worldwide on sectors such as agriculture, energy, transportation, construction and heavy industry.

If the next U.S. administration embraced a Green New Deal and gave more, it could cajole other economic powers such as Britain, China, France and Japan to do the same, hastening the world’s transition away from fossil fuels. According to a Center for American Progress paper from 2017, each $1 billion provided to the Green Climate Fund could prevent carbon pollution equivalent to 51 million gallons of gasoline, “increase the climate preparedness of more than 55 million people” and help bring in an additional $2.4 billion in financing from other sources. Imagine if the United States said that, in return for stronger climate mitigation commitments from recipient countries, it would triple Obama’s initial pledge to $9 billion, give that every year and add a few billion more through agencies such as the U.S. Agency for International Development. (There is no stipulation in the Paris agreement of how much climate finance should come from each country, but a paper in the journal Global Environmental Politics calculated in 2015 that the United States’ fair share could be as high as 46 percent.)

Politically, this may be toxic for American voters. Polls show that Americans overwhelmingly accept the science of climate change, are increasingly worried about it and in theory support the notion that the government should address it — but they are more divided in their willingness to actually pay for climate action. Last year, a national poll by the Associated Press and the University of Chicago showed that 44 percent of Americans said they supported a carbon tax and 29 percent opposed one. But only 23 percent said they’d pay at least $40 per month to fight climate change.

Obviously, when campaigning in, say, Macomb County, Mich., the Democratic presidential nominee could emphasize the parts of the Green New Deal that are designed to appeal to white working-class swing voters, like the promise of green jobs. Another political defense is that spending the equivalent of a small fraction of the Pentagon’s budget on international climate programs is a savvy investment in the country’s economic future. Our $3 billion pledge to the Green Climate Fund costs the same as four B-2 Spirit stealth bombers.

The Obama administration was unable to offer large enough emission-reduction pledges or climate finance in 2015 because of the Republican-controlled Congress. Now a climate science denier occupies the White House, and his party still controls the Senate. In this context, discussing the shortcomings of the Green New Deal may seem a bit like debating the best way to groom a unicorn. The Green New Deal requires Democratic control of Congress and the White House, and even that may not be enough.

Still, that configuration could be just two years away — and it could endure for just two more years. The United States may have a narrow opportunity to pay down some of its historical debts, stem the tide of future climate refugees and manage the political instability that extreme warming would cause. The last chance came in 2009-2010, but the Senate failed, in part thanks to Obama’s bungling of the negotiations, to pass even domestic climate legislation. A decade elapsed, the world got warmer, the carbon budget was depleted, and the doomsday clock kept ticking.

The leaders of developing nations aren’t suckers, and they know how dire the problem is. They have something rich countries want (emissions reductions), and they’d be fools to just give it away for free, even if they could. If we want them to succeed, it’s going to cost us, and we’ll need to move quickly. The science is clear: We do not have another decade to waste.