A pro-Brexit protester, wearing a yellow vest and a mask depicting President Donald Trump, demonstrates in London.Henry Nicholls / Reuters

One would be hard-pressed to find a region of the world that populism didn’t touch in the 2010s. The decade brought us the election of Donald Trump in the United States and the Brexit vote in Britain. It witnessed the rise of the Alternative for Germany—the first far-right party to enter the country’s national parliament in decades—as well as the ascent of populist parties in countries such as Austria, Brazil, Italy, India, Indonesia, and Poland. By 2018, as many as 20 populist leaders held executive office around the world.

Populism took many (often overlapping) forms in the 2010s. Some countries experienced a socioeconomic version, pitting the working class against Big Business and cosmopolitan elites regarded as benefiting from the international capitalist system (as seen in places such as France and the United States). Others saw a cultural form thrive, focusing on issues of national identity, immigration, and race (as was the case in Germany and India). Perhaps the most common was anti-establishment populism, which pits “the people” against the political elites and the mainstream parties they represent.

These forms are likely to continue into the new decade, though the main issue at play will probably shift from immigration to climate change, populist promises will become policy, and democratic institutions will be put even further to the test.

If the 2010s were the years in which predominantly far-right, populist parties permeated the political mainstream, then the 2020s will be when voters “are going to see the consequences of that,” Daphne Halikiopoulou, an associate professor of comparative politics at the University of Reading, in England, told me. In some ways, they already have. In Britain, the 2016 vote to leave the European Union—and the political fallout it caused—is likely to be fulfilled at the end of January, following Prime Minister Boris Johnson’s resounding victory in last month’s general election. Elsewhere, populist parties have already made their impact—if not through passing legislation at the head of government, then by applying pressure in opposition.

Though this populist phenomenon rose to international consciousness in the past decade, its roots in fact stretch back further. In Austria, the right-wing Freedom Party served in a governing coalition from 2000 to 2005. During that same period, Britain’s U.K. Independence Party was on the ascent. In France, the far-right National Front advanced to the runoff of the 2002 presidential election (an achievement the party, which has since been renamed the National Rally, replicated in 2017). Countless other populist leaders already held power in countries such as Bolivia, Israel, and Hungary.

What the 2010s did, however, was give populist parties the ecosystem they needed to thrive—due to, among other things, the consequences of the 2008 global financial crash and the digital revolution. While the former contributed to greater inequality and the rejection of mainstream parties that were perceived to be perpetuating it, the latter resulted in the “transformation of … everyday life,” Catherine Fieschi, the executive director of the London-based consultancy Counterpoint and the author of Populocracy: The Tyranny of Authenticity and the Rise of Populism, told me. “We’ve become much more impatient; we don’t understand why things aren’t always just a click away. If Amazon Prime can do it, why can’t [the government] revamp the benefit system more quickly?”

In the 2020s, we will likely see many of the same characters who defined the previous decade remain at the fore. Italy’s Matteo Salvini, the leader of the far-right and nativist League party, has pledged to return to government as prime minister—and, if successful, to forge alliances with like-minded leaders, including Johnson and Trump. Indian Prime Minister Narendra Modi has signaled that he will press forward with his quest to further his Hindu-nationalist agenda—including defending his contentious Citizenship Amendment Act, which has spurred weeks of protests. In France, the National Rally, still buoyant after its European Parliament victory last spring, is setting its sights on consolidating local support through the country’s upcoming municipal elections.

Whereas much of the past decade revolved around arguments over issues of immigration and sovereignty, the 2020s could be dominated by a new, more pressing narrative: climate change. “The environment is going to become a very salient dimension of contestation,” Halikiopoulou said, noting that though political fragmentation across Europe led to an uptick in support for far-right populist parties, it also resulted in a surge for green parties in countries such as Germany and France. These parties will have to contend with figures such as Trump and populist parties in Europe, which have expressed open skepticism about climate change, branding it an elitist hoax or, at the least, an issue for which the establishment has promoted policies that disproportionately harm the poor. In this way, populist arguments about climate change resemble those about immigration. The populist argument was that “you have a liberal elite that has everything to gain from letting in lots of immigrants,” Fieschi said. “Climate policy and the Green New Deal ... is being depicted as the next way for the elite to screw over ordinary people.”

Even if the core issue changes, though, the test to liberal democracy will remain: Across Europe, populist leaders have displayed their willingness to tread over democratic institutions in order to see their political agendas realized—from Viktor Orbán’s crackdowns on academic and press freedom in Hungary to the right-wing populist Law and Justice party’s efforts to overhaul the state media and judiciary in Poland. As populist parties gain a stronger foothold, the 2020s could see more of the same.

When I asked Fieschi and Halikiopoulou whether this decade could see voters become as disillusioned with populist parties as they became with their more mainstream counterparts in the past one, both said it was possible—but unlikely, at least in the short term. “It’s going to be a very long-term thing to experience the disillusionment from a government that has failed you,” Halikiopoulou said. And even if voters do become dissatisfied with populist parties, Fieschi said, it doesn’t mean a return to the politics of the early 2000s.

“There is no normal to go back to.”

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.