EDITOR’S NOTE: This article is part of The Nation’s special issue on Barack Obama’s presidency, available in full here.

No fair evaluation of Barack Obama’s record on any major issue, including climate change, can underestimate two central facts of his presidency: He was the first African American to win the Oval Office; and he did so at a time, 150 years after the Civil War, when racist sentiment remained alive, well, and even popular, as Donald Trump’s 2016 campaign demonstrated.

All presidents confront opposition, but Obama encountered a level of hostility, even hatred, unique in modern US history. He received three times as many threats of violence during his first year in office as his predecessors did, according to Secret Service sources cited by The Washington Post, many of them “racially tinged.” His very legitimacy as president was disputed for years by the birther movement led by Trump with the silent assent of top Republicans. Before Obama even took office, Mitch McConnell, then the Senate minority leader, ordered Republicans to oppose any and all of his initiatives—never mind that millions of Americans were losing their jobs and their homes amid the economic crisis Obama inherited.

Now Trump and the forces he represents will try to undo what Obama achieved. And nowhere are the stakes higher than on climate change (except for nuclear war, where it’s all too easy to imagine the volatile Trump unleashing catastrophe).

Climate change is not like other issues. Terrible, terrible suffering and damage could result from Trump’s policies on immigration, abortion, economic inequality, and more. Those policies, however, can eventually be reversed and the suffering eased. Not so with climate change. There are points of no return—in fact, we’ve already passed a number of them. Thanks to earlier emissions of carbon dioxide and other heat-trapping greenhouse gases, the earth is experiencing record temperatures, melting ice, rising seas, and more droughts and extreme weather—with much more of the same locked in for years to come.

Our civilization is racing toward the cliff. Our only hope was and remains to rapidly phase out carbon-based fuels in favor of clean energy. The transition would have been challenging enough if Hillary Clinton, with her pledge to erect 500 million solar panels nationwide, had succeeded Obama. Now, with Trump and his fossil-fuel buddies in charge, one shudders to contemplate the future.

But giving up is not an option, and there are some bright stars by which to navigate these treacherous waters. For starters, what Trump intends to do may turn out to be very different from what he actually accomplishes. Judging by the hapless rollout of his White House transition, he could end up presiding over a remarkably ineffective administration. He also could overreach, as Republicans did under House Speaker Newt Gingrich in the 1990s, when their attempts to gut environmental laws and defund the federal government triggered an electoral backlash.

Trump will also face determined opposition and serious constraints at home and abroad. The most heartening development in US climate politics during the Obama years was the emergence of a sophisticated, militant mass movement. Employing tactics ranging from civil disobedience to old-fashioned coalition-building, the movement blocked or closed hundreds of coal plants and killed the Keystone XL pipeline, among other victories. Movement groups promise ferocious resistance to Trump, and they’ll have some support from mainstream voices. Hundreds of businesses and communities are already reaping the economic advantages of clean energy. And while Trump has promised to withdraw from the Paris Agreement, virtually every other country in the world remains committed to its goal of limiting the global temperature rise to “well below” 2 degrees Celsius—and some of these countries have the muscle to make Trump think twice. China has already cautioned him to honor the agreement, and Nicolas Sarkozy, the former president of France, has suggested economic sanctions if Trump follows through on his vow.

In anticipation of the battles ahead, it’s instructive to examine Obama’s climate record over the last eight years. There are lessons in what he did and did not achieve that can be applied in confronting his successor. Trump undeniably threatens disaster, but he might be thwarted if people resist as though their lives depend on it. Which they do.

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“How will history judge President Obama on climate change?” I asked John Podesta in 2013. As White House chief of staff in the late 1990s, Podesta steered Bill Clinton through the impeachment crisis, giving him a deep familiarity with Republican obstructionism. In 2008, he ran Obama’s transition team. And for years, unlike most Washington power brokers, he has grasped the urgency of climate change.

Podesta praised Obama for expending political capital to address the crisis, but he acknowledged that, 50 years from now, this would be seen as insufficient. Obama, Podesta told me, would go down in history as a president “who couldn’t break through contemporary politics to the place we need to go.”

“Contemporary politics” was Podesta’s polite term for the array of powerful forces that contend for dominance in Washington. The White House, of course, is one of those forces, but only one. An aggressive opposition party that controls one or both houses of Congress, as Obama confronted for most of his presidency, is another—and it’s a formidable obstacle. So is corporate power in general, a fact carrying special weight when it comes to climate change, where Obama faced perhaps the most powerful business enterprise in history: Big Oil and the rest of the fossil-fuel industry. The arbiters of popular discourse—TV networks, leading newspapers, and other pillars of the corporate media—are yet another power center; they deserve a special circle in hell for sustaining the lie that climate change is more a matter of political opinion than of scientific fact.

None of this absolves Obama from his own share of responsibility for his climate record. Podesta mentioned one self-inflicted wound: More than a couple of the president’s top advisers in the first term shared the dismissive attitude toward climate change that is typical inside the Beltway. In 2008, candidate Obama displayed a sure grasp of climate science and policy. He pledged to make “polluters pay” for overheating our shared atmosphere, leveraging the power of the market to drive change. He endorsed cutting emissions 80 percent by 2050, as called for by the prevailing science. Once in office, however, Obama scaled back his ambitions and emphasized conciliation. He sought bipartisanship even as his political enemies demonstrated repeatedly that they wanted only to foil him. Not a single House Republican voted for Obama’s economic-recovery plan, initiating a pattern of obstructionism that persisted for the rest of his presidency.

That plan, which passed in 2009, when the Democrats briefly controlled Congress, contained two of Obama’s early climate achievements: $80 billion in funding for renewable energy, which sparked the subsequent stratospheric growth in wind and solar power, and a substantial boost in vehicle fuel efficiency. But these advances would be more than offset by Obama’s “all of the above” energy policy, which made the United States the world’s leading producer of oil and gas by the end of his first term.

Further contradicting his 2008 campaign rhetoric, Obama endorsed a weak, convoluted cap-and-trade bill drafted by corporate polluters in league with the self- described pragmatists at the Environmental Defense Fund and the Natural Resources Defense Council. Republicans savaged the bill as “cap and tax,” while activists found it impossible to defend. “Most people don’t support cap and trade. They can’t even understand it,” one activist explained after the bill crashed and burned in 2010.

Apparently stung by that defeat, Obama then committed a second grievous mistake: He went silent on the climate issue for the rest of his first term. Obama’s failure to use his bully pulpit to educate Americans about the danger of climate change and the economic benefits of addressing it ceded the discussion to the climate deniers, who duly rolled back the growing public support for action. “On the question of whether climate change was real, man-made and serious, we lost about 20 points…when our guy had the [presidential] megaphone,” said Steven Biel, a lobbyist for the liberal pressure group MoveOn during Obama’s first term. “That’s not supposed to happen!”

After winning reelection in 2012, Obama pursued a more aggressive climate agenda, aided by Podesta, who returned to the White House to coordinate the effort. Apparently deciding that appealing to Republicans was a lost cause, Obama relied almost entirely on executive actions.

The most important advance was the breakthrough with China. The two countries had been at loggerheads since the early 1990s, with China arguing that nations with millions of people trying to ascend from poverty should not be required to limit emissions when it was rich countries over the past 200 years that had caused the problem. The United States countered that avoiding catastrophe was impossible unless big developing countries also cut emissions. A series of quiet high-level meetings that had started even before Obama was elected led to a joint statement in 2014 that committed both China and the United States to substantial reductions.

The United States would achieve its reductions in part via a second Obama initiative, the Clean Power Plan, which Trump has promised to kill. Currently tied up in the courts, the plan targets coal-fired power plants, the source of roughly one-third of US emissions. The usual suspects howled about Obama’s alleged war on coal, and it’s true that the plan would make additional plants highly unlikely. But it also falls far short of what is necessary. As the Obama administration had done since its first days in office, it “moved the goalposts” by measuring future reductions against a base year of 2005. Applying the standard base year of 1990 shrinks the promised reductions to 7 percent—well under the 40 percent minimum dictated by science.

The US-China agreement broke the deadlock that had doomed global climate negotiations for decades, paving the way for the Paris Agreement of 2015. The agreement’s emission cuts are voluntary, but as I reported from Paris at the time, the blame lay not with Obama but, again, with congressional Republicans. Making the cuts mandatory would have turned the agreement into a treaty; a treaty needs approval by the Senate, where climate deniers would have gleefully eviscerated it.

In the end, Podesta’s estimate of the verdict of history still holds: Obama did more in his second term, but nowhere near enough. The climate emergency is still advancing faster than the world’s response, not least because of the United States’ inadequate actions. Crushing impacts are now inevitable, especially for the world’s most vulnerable people and communities; the imperative is somehow to avoid the unmanageable while managing the unavoidable.

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Trump makes that challenge much harder; there’s no denying it. But he does have weaknesses, and the lessons of the Obama years suggest ways to exploit them.

First, talk about climate change—often, to all sides, in plain language that emphasizes the jobs and other economic benefits of a rapid shift to clean energy. Republicans have gotten away with climate denial in part because they haven’t been called to account for it. “The polling data [show] that 53 percent of self-designated Republicans under the age of 35 see climate-change denial as ignorant, out of touch, or crazy,” said Sheldon Whitehouse, the Democratic senator from Rhode Island who has been the most outspoken member of Congress on climate issues. “The current stance of the Republican Party in the denial camp is not one that can survive under scrutiny.”

Second, be bold, not incremental. Stand for what science demands without apology. Do not be seduced into compromising for the sake of compromise or to gain “influence.” The best course is to build power at the grassroots level and bring it to bear on Washington, threatening to vote out elected officials if they resist the people’s will.

Third, expand alliances. At this point, pretty much everyone except Trump and his Republican allies want action on climate change. The climate movement has been strengthened in recent years by aligning with economic-, social-, and racial-justice organizations, but there are also important allies to be had in the business class, state and local governments, and overseas. These political actors can exert power in ways unavailable to grassroots activists.

Finally, get in the streets. What most drove climate progress in the Obama years was the same thing that led Richard Nixon more than 40 years ago to create the Environmental Protection Agency and sign the nation’s foundational environmental laws: seeing large numbers of people in the streets demanding reform.

The pressure exerted by ordinary people who get arrested but also do the tedious yet irreplaceable work of attending regulatory hearings, writing to local media and public officials, and much more is one of the few forces that can counterbalance the elite interests that otherwise dominate inside Washington. Take it from no less of a political insider than ExxonMobil: After a reported 400,000 people thronged the streets of New York City demanding climate action in 2014, the oil giant’s media officer told me, “That many people marching is clearly going to put pressure on government to do something.”

Even, perhaps, a government headed by Donald Trump.

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