If Donald Trump wins a second term, and his administration realizes conservative advocacy groups’ plans to dismantle environmental protections and drill, baby, drill, the United States is in for four years of relentless carbon pollution. In other words, another Trump presidency all but guarantees a complete abnegation of the country’s climate duties from 2025 to 2029. And as climate scientists say, emissions anywhere mean global warming everywhere: The United States’ heat-trapping contributions to the atmosphere during those years will make the world warmer than it would be without them. Already, the warming that humanity has locked in will bring many places to the edge of habitability, and adding to that damage would be an “unmitigated disaster,” the atmospheric-climate scientist Veerabhadran Ramanathan told me.
“But if it’s just four years, we can survive it,” he added, to my surprise. “Unless that four years becomes 20 years … But if it is just four years, then you can recover.”
A second Trump presidency is the open question looming over climate science. Given that global warming is still yet to be reined in, how damaging could four years of Trump be to our collective climate outcome? The answer may be both less fatalistic and more complex than that a president wedded to fossil fuels will condemn the world to significantly worse warming. The short of it, according to two distinguished climate scientists I spoke with, is this: Trump’s four years would surely be damaging, but wouldn’t doom the planet. A public reckoning is coming whether he wins or not, and Trump’s hostile posture on climate could sap U.S. ambitions in a future where geopolitical power is likely to align with a country’s capacity to power itself.
Ramanathan is a distinguished professor at Scripps Institution of Oceanography at UC San Diego. He expects that another Trump term will make the world more confused and chaotic. But he also expects that, sometime this decade, regardless of who is president in 2025, the public will inevitably come to its senses about the dangers of climate change—out of sheer fear of how climate-addled our lives are becoming—and demand the type of radical change needed to reach zero emissions.
He feels sure this will happen when the world officially surpasses the 1.5-degree-Celsius benchmark, which he and other scientists predict will come to pass around 2030. “I need you to know that I feel we are going to solve this problem,” he said. “My feeling is the politicians are not signing on to drastic reductions because they feel they don’t have public support.” But in his view, that public support will solidify soon, because of how dire the landscape of climate chaos is becoming.
He says he believes this because he has seen it happen before: In 1975, Ramanathan discovered that chlorofluorocarbons, used in aerosols and refrigerants, contributed to the greenhouse effect. Other scientists found that the gases also deplete the ozone layer, the very thing protecting all life on Earth from being sizzled to a crisp by unmitigated solar radiation. This understanding led, in 1987, to countries finalizing the Montreal Protocol, which began the process that ultimately banned chlorofluorocarbons and other gases that were causing a worrying hole to open in the ozone layer over Antarctica. The protocol was successful; the United Nations says the ozone layer is on track for a full recovery.
And it all happened because a critical mass of global leaders decided to act on their well-founded fear—even when a Republican who was once pilloried for saying trees cause pollution held the U.S. presidency. “The Montreal Protocol was all figured out during President Reagan’s time, because people got scared when they saw that Antarctic ozone hole,” Ramanathan said. It probably helped to have so clear and singular an object—a literal hole widening in the sky—on which to place their anxieties. But he thinks the same will happen when people are scared enough by climate change, even if its dangers are more phantasmagoric, and he believes we’re getting close to that point. In 2023, when nearly 50 percent of the days were more than 1.5 degrees warmer than they were during the benchmark period of 1850–1900, the U.S. suffered 28 disasters costing more than $1 billion in damages. “I think you have to put it in terms of human suffering,” Ramanathan told me. “How many people lost their homes? How many people were out on the street, made miserable?” One can start to imagine more clearly the misery that consistently exceeding 1.5 degrees Celsius will bring.
He is quick to add that passing this threshold will have devastating consequences for billions of people. He sees it like a fall from a cliff: For the “top 1 billion” wealthiest people on Earth—a group he puts himself and me squarely in—passing 1.5 degrees Celsius would amount to falling off a cliff 10 or 12 feet high. That’s not nothing: “We may survive with broken bones,” he said. But for the poorest 3 billion, passing 1.5 degrees is a fall from a 100-foot cliff. That’s lethal. “It’s a huge moral issue,” he said, because the “top 1 billion” are the ones pushing the bottom 3 billion off that cliff: They are—we are!—responsible for the majority of the emissions that made the cliff in the first place.
If a rush of global sentiment does finally prompt a dramatic reversal in the trend line of carbon emissions, its full effects may not be felt for a decade or more. There is a long latency time between carbon emitted today and the impact it has on the world’s temperature. “The next 20 years are already locked in with respect to climate. But the 20 years after that will be determined by what we are doing at the moment,” Anders Levermann, a climate scientist at the Potsdam Institute for Climate Impact Research, in Germany, told me. Without major efforts to eliminate all carbon emissions now, the Earth will be doomed to another degree or two of warming down the line.
Right now, global efforts to curb some emissions could lessen the pitch of the warming curve’s upward slope. But it will still go up. A Trump term would likely steepen it for a while, and every fraction of a degree of warming pushes Earth’s systems toward ever more unprecedented extremes, and more of the population toward suffering. But only one thing will actually bend that curve and halt the warming: zeroing out carbon emissions.
Levermann has a slightly different view from Ramanathan’s. He agrees that four years of a Trump term would be harmful yet recoverable. But more specifically, he thinks the U.S. would be shooting itself in the foot. The transition to renewable energy is now inevitable. “In 20 years, we as a globe have to be at zero emissions,” Levermann said. For four years, the U.S. would be taking itself out of the race to achieve that. All that would do is hamper the U.S.’s own power in a world that will change without it.
Like Ramanathan, Levermann sees a tipping point coming where climate disasters will spark dramatic action. “Eventually, people will not get around the fact that climate change is endangering our way of living,” leading to chaos within society that “might topple our systems,” he said. And eventually that will push every country in the world to turn wholeheartedly to renewable energy sources. “We don’t all have to become vegetarians. It’s great to do; there are a million reasons to do it,” he said. But for solving the climate problems? We have to stop burning oil, gas, and coal.”
“When you get a Trump presidency, that just means you delay the United States’ path into the future by four years,” Levermann said. America’s climate policy under President Joe Biden has been full of contradictions. The U.S. entered 2024 producing more oil than any country ever has. Yet Levermann thinks Biden’s presidency has ultimately put the U.S. onto the renewable-energy path with the Inflation Reduction Act. The U.S. might still be using fossil fuels, and even increasing its use of them, but it is moving toward an inevitable oil-free future. What matters most, Levermann says, is that “we are at zero in 20 years.”
The European Union is also planning its own renewable-energy future. “Two big economic entities are on the path towards renewable energies,” Levermann says. “And if Trump for ideological reasons gets away from this path again, he’ll just push the U.S. into economic disadvantage.”
The U.S. has a natural upper hand in the energy landscape of the future, if it’s willing to use it: Its size guarantees that it will be sunny, or windy, somewhere in the country at any given time. If it wanted, Levermann says, the U.S. is one of the few countries that could be entirely energy-independent when the world moves off all fossil fuels. A country like Germany, where he lives, is too small to be energy-independent: One troublesome weather system could engulf the whole country at once. The EU, however, could be energy-independent as a whole. China, meanwhile, is another case like the U.S., Levermann said: It’s a big-enough landmass to go it alone. “And they’re going to do it. China’s on that path of doing this. They don’t talk about it, but they do it.”
Both scientists’ perspectives rest on the assumption that people will decide to stabilize the global temperature because, as Levermann says, “that’s the rational thing to do.” After all, human civilization evolved within a 10,000-year envelope of a stable climate. And so the major powers of the world must soon accept that they have to stop emitting carbon to maintain that civilization, or any semblance of a stable future. “And then start the race towards the best way to do that, because countries which do this best, fastest, will be the winners,” Levermann said. A United States led by Donald Trump simply won’t be one of them.