Ever since some of the earliest projections of climate change were made back in the 1970s, they have been remarkably accurate at predicting the rate at which global temperatures would rise. For decades, climate change has proceeded at roughly the expected pace, says David Armstrong McKay, a climate scientist at the University of Exeter, in England. Its impacts, however, are accelerating—sometimes far faster than expected.

For a while, the consequences weren’t easily seen. They certainly are today. The Southwest is sweltering under a heat dome. Vermont saw a deluge of rain, its second 100-year storm in roughly than a decade. Early July brought the hottest day globally since records began—a milestone surpassed again the following day. “For a long time, we were within the range of normal. And now we’re really not,” Allegra LeGrande, a physical-research scientist at Columbia University, told me. “And it has happened fast enough that people have a memory of it happening.”

In fact, a growing number of climate scientists now believe we may be careening toward so-called tipping points, where incremental steps along the same trajectory could push Earth’s systems into abrupt or irreversible change—leading to transformations that cannot be stopped even if emissions were suddenly halted. “The Earth may have left a ‘safe’ climate state beyond 1°C global warming,” Armstrong McKay and his co-authors concluded in Science last fall. If these thresholds are passed, some of global warming’s effects—like the thaw of permafrost or the loss of the world’s coral reefs—are likely to happen more quickly than expected. On the whole, however, the implications of blowing past these tipping points remain among climate change’s most consequential unknowns: We don’t really know when or how fast things will fall apart.

Some natural systems, if upended, could herald a restructuring of the world. Take the Thwaites Glacier in West Antarctica: It’s about the size of Florida, with a protruding ice shelf that impedes the glacier’s flow into the ocean. Although the ice shelf's overall melt is slower than originally predicted, warm water is now eating away at it from below, causing deep cracks. At a certain point, that melt may progress enough to become self-sustaining, which would guarantee the glacier’s eventual collapse. How that plays out will help determine how much sea levels will rise—and thus the future of millions of people.

The fate of the Thwaites Glacier could be independent of other tipping points, such as those affecting mountain-glacier loss in South America, or the West African monsoon. But some tipping points will interact, worsening one another’s effects. When melt from Greenland’s glaciers enters the ocean, for example, it alters an important system of currents called the Atlantic Meridional Overturning Circulation. The AMOC is like a conveyor belt, drawing warm water from the tropics north. The water’s salinity increases as it evaporates, which, among other factors, makes it sink and return south along the ocean floor. As more glacial fresh water enters the system, that conveyor belt will weaken. Right now it’s the feeblest it’s been in more than 1,000 years.

[Read: I’ve hit my climate tipping point]

A shutdown of that ocean current could dramatically alter phenomena as varied as global weather patterns and crop yields. Messing with complex systems is chilling precisely because there are so many levers: If the temperature of the sea surface changes, precipitation over the Amazon might too, contributing to its deforestation, which in turn has been linked to snowfall on the Tibetan plateau. We may not even realize when we start passing points of no return—or if we already have. “It’s kind of like stepping into a minefield,” Armstrong McKay said. “We don’t want to find out where these things are by triggering them.”

One grim paper that came out last year, titled “Climate End Game,” mapped out some of the potential catastrophes that could follow a “tipping cascade,” and considered the possibility that “a sudden shift in climate could trigger systems failures that unravel societies across the globe.” Chris Field, the director of the Stanford Woods Institute for the Environment and a contributor to several IPCC reports, warned that “at some point, the impacts of the climate crisis may become so severe that we lose the ability to work together to deliver solutions.”

James Hansen, one of the early voices on climate, says that measures to mitigate the crisis may now, ironically, be contributing to it. He published a working paper this spring suggesting that a reduction in sulfate aerosol particles—or the air pollution associated with burning coal and the global shipping industry—has contributed to warmer temperatures. That’s because these particles cause water droplets to multiply, which brightens clouds and reflects solar heat away from the planet’s surface. Though the paper has not been peer-reviewed, Hansen predicts that environmentally minded policies to reduce these pollutants will likely cause temperatures to rise by 2 degrees Celsius by 2050.

[Read: ‘Things don’t always change in a nice, gradual way’]

Even before the climate gets to that point, we may face a dramatic uptick in climate-related disasters, says William Ripple, a distinguished professor of ecology at Oregon State University and the lead author of a recent commentary on the “risky feedback loops” connecting climate-driven systems. There’s a sense of awe—in the original meaning of inspiring terror or dread—at witnessing such sweeping changes play out across the landscape. “Many scientists knew these things would happen, but we’re taken aback by the severity of the major changes we’re seeing,” Ripple said. Armstrong McKay likened the challenge of being a climate scientist in 2023 to that faced by medical professionals: “You put a certain emotional distance between you and the work in order to do the work effectively,” he said, “that can be difficult to maintain.”

Although it may be too late to avert some changes, others could still be staved off by limiting emissions. LeGrande said she worries that talking about tipping points may encourage people to think that any further action now is futile. In fact, the opposite is true, Ripple said. “Scientifically, everything we do to avoid even a tenth of a degree of temperature increase makes a huge difference.”

Pull up a sticky green lawn chair, everyone. It’s time for another round of Mounting Democratic Jitters, cherished summer pastime from Wilmington to the West Wing. Today’s installment: Cornel West, unlikely MAGA accessory.

West, the famed academic and civil-rights activist, is a Green Party candidate for president. He probably will not win. Not a single state or, in all likelihood, a single electoral vote. But he remains a persistent object of concern around the president these days.

I’ve talked with many of these White House worrywarts, along with their counterparts on Joe Biden’s reelection team and the usual kettles of Democratic anxiety who start bubbling up whenever the next existential-threat election is upon us. Even with the nuisance primary challenger Robert F. Kennedy Jr. polling in the double digits, West inhabits a particular category of Democratic angst, the likes of which only the words Green Party presidential candidate can elicit.

You can understand the sensitivities, given the history. Democrats still recoil at the name Jill Stein, the Green Party nominee in 2016, whose vote total in key battlegrounds—Michigan, Wisconsin, and Pennsylvania—wound up exceeding the margins by which Hillary Clinton lost in those states. What’s Dr. Stein doing these days, anyway?

“She is my interim campaign manager,” Cornel West told me this week in a phone interview. Not a joke, as Biden would say. Or an acid flashback. Apparently Ralph Nader was not available. Not Dennis Kucinich, either (already snapped up to run RFK Jr.’s campaign). It might be kind of funny if the stakes didn’t involve a return Trump ordeal in the White House.

“The fact that Jill Stein is running his campaign is a little on the nose,” one senior Democratic campaign strategist told me.

[Read: The first MAGA Democrat]

West has repeatedly denied that he might play a spoiler role. “I would say that most of the people who vote for me would not have voted for Biden,” he told me. “They would have probably stayed home.” In a recent CNN appearance, West dismissed the two parties as a “corporate duopoly” and professed “great respect for my dear brother Ralph Nader and great respect for sister Jill Stein.” This did nothing to assuage Democratic jitters.

I asked West whether he would campaign all the way to Election Day 2024, or if he might reconsider his venture at some point. “My goal is to go all the way to November,” he said, but allowed that circumstances could change and so could his plans. “I’m trying to be a jazzlike man,” he said. “Trying to be improvisational.”

In his campaign-launch video, West promised that his candidacy would focus on core progressive issues such as health care, housing, reproductive rights, and “de-escalating the destruction” done to the Earth and our democracy. “Neither political party wants to tell the truth,” West said, by way of explaining why he is running as a third-party candidate.

Notably, West has asserted that NATO was as much to blame for Russia’s war in Ukraine as the Kremlin. He has railed against the coalition as an “expanding instrument” of Western aggression, which he says is what provoked Russia’s onslaught. “This proxy war between the American Empire and the Russian Federation could lead to World War III,” he wrote in a social-media post calling for diplomatic talks. West also dismissed as a “sham” a House resolution—passed Tuesday—that affirmed U.S. support for Israel. “The painful truth is that the Israeli state—like the USA—has been racist in practice since its inception,” West wrote on Twitter.

Several Democrats were eager to tell their own truths about West’s endeavor, expressing uniform exasperation.

“This is not the time in order to experiment. This is not the time to play around on the margins,” warned Democratic National Committee Chair Jaime Harrison during a recent appearance on MSNBC. “What we see is a lot of folks who want to be relevant and try to be relevant in these elections and not looking at the big picture.”

“Too little attention is being paid to this,” David Axelrod, the former top Barack Obama strategist, told me. Axelrod recently gave voice to the gathering Democratic freak-out when he tweeted out some basic historical parallels. “In 2016, the Green Party played an outsized role in tipping the election to Donald Trump,” he wrote. “Now, with Cornel West as their likely nominee, they could easily do it again.”

In our interview, Axelrod noted that the 2020 race between Biden and Trump, in which neither Stein nor West was on the ballot, underscores how slim the Democrats’ margin of error remains. “When you have three states that you won by 41,000 votes combined, you just cannot afford to bleed votes, even a few of them,” Axelrod told me.

Ben Wikler, the Democratic Party chair of one of these states—Wisconsin—said he expects Trump allies to help prop up any third-party effort as a way to undermine Biden. “Regardless of the motivations of third-party candidates themselves, they can have the effect of delivering net votes to Trump next year,” Wikler said, “especially if a Trump-aligned super PAC pours money into targeted messages,” he added. “And those are exactly the kind of cynical games you have to expect.”

Cedric Richmond, a former Democratic congressman and White House adviser who recently signed on as co-chair of the Biden campaign, called West a “substantive person.” But Richmond argued that Biden has earned the support of the left through his record on the environment, health care, gun reform, and other progressive causes. “They also know that [Biden] could have done a hell of a lot more if not for this hostile Supreme Court,” Richmond told me. “And they know they got this hostile Supreme Court because ‘Hillary wasn’t good enough,’ because ‘we weren’t happy and we wanted to support Jill Stein’ or whatever the reason was at the time.” Now that voters have experienced a Trump presidency, he said, the cost of casting a protest vote with a third-party candidate should be much more apparent. “I think people have seen this movie, and they know the ending,” Richmond said.

In recent days, the putative-centrist outfit No Labels—which many Democrats have been quick to label as a pro-Trump collaborator—has been the main source of third-party hand-wringing.  The group is trying to recruit a so-called unity ticket that would appear on ballots across the country, possibly led by Senator Joe Manchin, the West Virginia Democrat.

[Read: Joe Lieberman weighs the Trump risk]

“The idea that a third-party candidate won’t hurt the Democratic nominee is preposterous on its face,” Matt Bennett, executive vice president of Third Way, a center-left policy think tank that lately has been focused on stopping No Labels, told me. Recent polls show that in a head-to-head race between Trump and Biden, Trump is more likely to benefit when a third-party candidate is added to the mix. Likewise, an NBC survey from last month revealed that 44 percent of registered voters would be open to a third-party candidate—and there were considerably more Democrats saying this (45 percent) than Republicans (34 percent).

But Bennett explained that if No Labels does not recruit a serious candidate to actually run, the group will remain a largely hypothetical menace. West, meanwhile, is definitely running. The Green Party has an organizational structure in place in many states that will ensure the nominee’s position on general-election ballots. West has deep roots on the left, and is better known than Stein was in 2016. Like Clinton, Biden has faced uncertainty about how much enthusiasm he can expect from his own party, especially young progressives.

“Dr. West has a huge following among college-age voters and a lot of folks who are more interested in social movements than they are in supporting Democratic or Republican candidates,” Basil Smikle, a Democratic strategist who was the executive director of the State Democratic Party of New York from 2015 to 2018, told me.

West was a vocal supporter of Senator Bernie Sanders’s presidential campaign in the 2020 Democratic primary. He has said that he wound up voting for Biden in the general election because “a fascist catastrophe is worse than a neoliberal disaster.” He also dubbed Biden “mediocre” and “milquetoast” (a tepid endorsement, let’s say).

Supporters of Biden are hopeful that the blessing of progressive allies such as Sanders, who endorsed his reelection in April, will insulate the president from the threat of West-inspired defections to the Green Party. “What Bernie can do is say, ‘Look man, we thought the existential threat of Trump had waned, but it’s still here,’” Smikle said. “We need you to show up again.”  

Another prominent Bernie booster from 2020, Representative Alexandria Ocasio-Cortez, endorsed Biden during a recent appearance on the podcast Pod Save America. The host Jon Favreau asked a follow-up about what she thought of West. Ocasio-Cortez appeared to tread carefully but sounded deferential. “I think Dr. West has an incredible history in this country,” she said. “What he gives voice to is incredibly important.” She went on to slam No Labels as a source of great concern, given “the sheer amount of money and bad-faith actors involved with it.”

“Not all third-party candidacies are created equal,” Ocasio-Cortez summarized. But she landed on a pragmatic point. “The United States has a winner-take-all system, whether we like that or not,” she said, adding that the cost of messing around could be fascism. “We have to live with that reality,” she said. Live with Joe Biden, in other words. Because the alternative is far worse—not a joke.