Donald Trumps decisive victory is a stunning setback for climate change.The Republican President-elects return to the White House means the country is going to squander precious momentum, unraveling hard-won policy progress that was just beginning to pay off, all for the second time in less than a decade.It comes at a moment when the world cant afford to waste time, with nations far off track from any greenhouse gas emissions trajectories that would keep our ecosystems stable and our communities safe. Under the policies in place today, the planet is already set to warm by more than 3C in the coming decades.Trump could push the globe into even more dangerous terrain, by defanging President Joe Bidens signature climate laws. In fact, a second Trump administration could boost greenhouse gas emissions by four billion tons through 2030 alone, according to an earlier analysis by Carbon Brief, a well regarded climate news and data site. That will exacerbate the dangers of heat waves, floods, wildfires, droughts, and famine, as well as increase deaths and disease from air pollution, inflicting some $900 million in climate damages around the world, Carbon Brief found.I started as the climate editor at MIT Technology Review just as Trump came into office the last time. Much of the early job entailed covering his systematic unraveling of the modest climate policy and progress that President Barack Obama had managed to achieve. I fear it will be far worse this time, as Trump ambles into office feeling empowered and aggrieved, and ready to test the rule of law and crack down on dissent.This time hell be staffed all the more by loyalists and idealogues, who have already made plans to force out civil servants with expertise and experience across federal agencies, including the Environmental Protection Agency. Hell be backed by a Supreme Court that he moved well to the right, and which has already undercut landmark environmental doctrines and the powers of federal regulatory agencies.This time the setbacks will sting more, too, because the US did finally manage to pass real, substantive climate policy, through the slimmest of congressional margins. The Inflation Reduction Act and Bipartisan Infrastructure Law allocated massive amounts of government funding to accelerate the shift to low-emissions industries and rebuild the US manufacturing base around a clean energy economy.Trump has made clear he will strive to repeal as many of these provisions as he can, tempered perhaps only by Republicans who recognize that these laws are producing revenue and jobs in their districts. Meanwhile, throughout the prolonged presidential campaign, Trump or his surrogates pledged to boost oil and gas production, eliminate federal support for electric vehicles, end power plant pollution rules, and remove the US from the Paris climate agreement yet again. Each of those goals stand in direct opposition to the deep, rapid emissions cuts now necessary toprevent the planet from tipping past higher and higher temperatures.Project 2025, considered a blueprint for the early days of a second Trump administration despite his insistence to the contrary, calls for dismantling or downsizing federal institutions including the the National Oceanic and Atmospheric Administration and the Federal Emergency Management Agency. Any success in doing so threatens to cripple the nations ability to forecast, track, or respond to storms, floods, and fires, similar to those that have devastated communities in recent months.Observers Ive spoken to fear the Trump administration will also revert the Department of Energy, which under Biden had evolved its mission toward developing low-emissions technologies, back to the primary task of helping companies dig up more fossil fuels.The US election could create global ripples as well, and very soon. US negotiators will meet with their counterparts at the annual UN climate conference that kicks off next week. With Trump set to move back into the White House in January, they will have little credibility or leverage to nudge other nations to step up their commitments to reduce emissions.But those are just some of the direct ways that a second Trump administration will enfeeble the nations ability to drive down emissions, and counter the growing dangers of climate change. He also has considerable power to stall the economy and sow international chaos amid a moment of escalating conflicts in Europe and the Middle East.Trumps eagerness to enact tariffs, slash government spending, and deport major portions of the workforce may stunt growth, drive up inflation, and chill investment. All of that would make it far more difficult for companies to raise the capital and purchase the components needed to build anything in the US, whether wind turbines, solar farms, and seawalls, or buildings, bridges, and data centers.President-elect Donald Trump speaks at an election night event in West Palm Beach, Florida. WIN MCNAMEE/GETTY IMAGESHis clumsy handling of the economy and international affairs may also help China extend its dominance in producing and selling the components of the energy transition, including batteries, EVs, and solar panels, to customers around the globe.If one job of a commentator is to find some perspective in difficult moments, I admit Im mostly failing in this one.The best I can do is to say that there will be some meaningful lines of defense. For now at least, state leaders and legislatures can continue to enact and implement stronger climate rules. Other nations could step up their efforts to cut emissions and assert themselves as global leaders on climate.The private industry will likely continue to invest in and build businesses in climate tech and clean energy, since solar, wind, batteries and EVs have proven themselves as competitive industries. And technological progress can occur no matter who is sitting in the round room on Pennsylvania Avenue, as researchers continue striving to develop cleaner, cheaper ways of producing our energy, food, and goods.By any measure, the job of addressing climate change is now much harder. Nothing, however, has changed about the stakes.Our world doesnt end if we surpass 2 C, 2.5 C, or even 3 C, but it will steadily become a more dangerous and erratic place. Every tenth of a degree remains worth fighting forwhether in two, four, or a dozen years from nowbecause every bit of warming that nations pull together to prevent eases future suffering somewhere.So as the shock wears off and the despair begins to lift, the core task before us remains the same: to push for progress, whenever, wherever, and however we can.