The urgency of climate change is finally dawning on the public. Two-thirds of Democrats now say they view global warming as a “critical threat,” and most call it the most important issue to discuss in presidential debates. The Democratic presidential candidates are paying attention, too. Many have released detailed climate plans; most have promised to refuse campaign contributions from fossil fuel industry executives; and nearly all support having a climate-only debate.
This sudden interest is understandable. The climate crisis is playing out before our eyes in ways it never has before, with unprecedented heat waves, flooding, and storms around the globe. Scientists’ warnings have also become more dire in recent years, their worst-case scenarios reading more like dystopian fiction than reality.
But the most potent reason for voters to be concerned about climate change this year is that we’re running out of time to prevent some of its worst effects. The Intergovernmental Panel on Climate Change (IPCC) has determined that the world could hit 1.5 degrees Celsius of warming—the point at which irreversible damage begins—as soon as 2030. This time crunch has led some to say the 2020 election represents humanity’s last hope. “This is a climate crisis. An emergency,” Washington Governor Jay Inslee said last month during the first Democratic debate. “And it is our last chance in an administration—the next one—to do something about it.”
But how important is this election, really? Scientists and policy experts agree that 2020 isn’t literally the last chance to save humanity, but four more years of Trump undoubtedly shrinks our chances to ensure a future safe from catastrophe. U.S. emissions likely wouldn’t reduce at the necessary pace, and the lack of leadership on the international stage could cause countries to decelerate their own energy transitions. The planet wouldn’t be doomed quite yet, but it would be closer to doom than ever before.
Climate change is a global problem that must be addressed on a global scale, but the United States has an outsized role in whether that global effort succeeds or fails.
Historically, the U.S. has emitted more carbon dioxide into the atmosphere than any other country, making it the leading contributor to global warming. Today, it’s the second-largest emitter, after China. In order to maintain a stable climate, according to the IPCC, net global emissions must reach zero by 2050. To achieve that, emissions must start rapidly declining in or around 2020.
If Trump is reelected, that “would probably mean a stalling of U.S. emissions,” said Corrine Le Quéré, a climate scientist at the University of East Anglia. That’s already happening under Trump. While most developed countries—including the U.S.—have averaged between 1 and 2 percent emissions reductions per year over the last decade, emissions in the U.S. rose by 3.4 percent in 2018, in part due to Trump’s campaign to dismantle climate regulations. “At this stage, to limit climate change anywhere below two degrees [of] warming, the decreases in emissions in developed countries should be accelerating,” Le Quéré said.
Necessary carbon reductions in the U.S. are unlikely to happen if Trump is reelected—and not just because of his deregulatory campaign on behalf of polluters. “I’d say one of the worst things about another four years would be that it would allow the Trump Administration to continue packing the courts with conservative judges,” said Drew Shindell, a professor of earth science at Duke University.
Many of the administration’s attempts at regulatory rollbacks—of which there are 83 related to the environment, at last count—end up in the courts. So far, judges have delayed or stopped many of those policy moves, from vehicle emissions standards to efforts at promoting fossil fuel extraction on public lands. But four more years of Trump means four more years of lifetime judicial appointments for conservative judges who might be more inclined to allow the rollbacks. Each individual policy may leave a small mark on the country’s overall emissions picture, but the sum of them would doom reductions in the near term.
A Trump win in 2020 could discourage other countries from rapidly reducing their emissions, too. Historically, American political leadership has been hugely influential in international climate negotiations, said Andrew Light, a senior fellow at the World Resources Institute who helped negotiate the Paris Agreement during the Obama administration. “The United States was absolutely instrumental in getting the strong agreement out of Paris,” he said.
The Paris agreement, as currently drafted, is not enough to stave off the worst of global warming, but it was intended to be strengthened periodically—and since Trump announced his intention to pull the U.S. out of the agreement in June 2017, the leadership that was so crucial to the initial negotiations has been absent. The next deadline for more aggressive climate targets arrives at the end of 2020. Thus, Light said, “2020 has got to be an inflection point for the world.”
Michael Mann, a distinguished professor of atmospheric science at Penn State, feels likewise. “Another four years of Trump would probably render futile any efforts to limit planetary warming to 1.5 [degrees Celsius], which is necessary to avert ever-more catastrophic climate-change impacts,” he said in an email. Others think the effort to limit warming to 1.5 degrees is futile no matter the outcome of the election. “[It’s] hard to say four more years of Trump makes impossible something that seems unlikely either way,” Shindell said.
Experts like Le Quéré, however, hope that the target could still be met even if Trump wins, because U.S. emissions are not tethered irrevocably to the occupant of the White House. “The U.S. president alone would probably not completely remove the chance that the [1.5-degree] target is met, but cities and states in the U.S. would need to redouble their actions and other countries would need to work harder,” she said. That means efforts like the U.S. Climate Alliance—a group of governors representing half the states and more than half the population, committed to reaching Paris agreement goals with or without federal government help—would have to ramp up significantly during Trump’s second term. “Those particular four years are extremely important to keep the 1.5-degree limit in sight,” Le Quéré said.
No one disputes that. Waiting another four years to take aggressive action on climate change will have real consequences, which may include whether the world, led by the U.S., can keep warming below that limit. But even if warming exceeds that target, each additional fraction of a degree represents more destruction, more death. So in that sense, it will never be too late—not in 2024, not even in 2028—to prevent an even greater toll.