President Trump speaks to reporters on the South Lawn of the White House on Nov. 29, 2018. (Brendan Smialowski/AFP/Getty Images)

As might have been expected, President Trump refused to join the rest of the Group of 20 nations in endorsing a communique about climate change presented over the weekend. By now, nearly two years into the Trump administration, the United States’ climate isolationism is not remarkable.

It’s worth remembering, though, that the isolation is also not a function of Trump. It’s the culmination of more than a decade of the Republican Party’s political rhetoric, including fervent opposition to climate change legislation, and years of cable-news fulminating — overlaid with a president more willing to adhere to the cable-news view of politics than the nuanced one common in Washington.

In October, the Pew Research Center released polling showing the issues that were considered most important by American voters. The issue on which the parties were most apart was the treatment of minorities in the legal system — something of much more concern to Democrats than Republicans. Next was illegal immigration, which a much larger percentage of Republicans than Democrats identified as a very important problem.

Climate change, the scientifically acknowledged warming of the planet as a result of greenhouse gas emissions, was tied as the third-most divisive issue with gun violence and economic inequality.

(Philip Bump/The Washington Post)

This division is not new. Gallup polling going back 20 years shows that, since 2000, Democrats have always been more likely than Republicans to say that the effects of the changing climate can already be felt. Its 2018 polling noted that the gap widened this year, but 10 years ago, the headline was similar: “Sharp divergence on whether the effects of global warming are yet evident.”

(Philip Bump/The Washington Post)

That was 2008, in the wake of Al Gore’s film “An Inconvenient Truth,” which was released in May 2006 and helped spur a new political push for legislation related to climate change. 2008 was the election in which Republican presidential nominee John McCain advocated addressing the problem and in which Gore’s Alliance for Climate Protection began running ads showing political support for legislation. That included this famous spot.

The election of Barack Obama was joined by a bill, passed in the House in 2009, instituting a market-based system to reduce emissions, a middle-ground position on climate change according to more progressive Democrats that was to climate change what the Affordable Care Act was to health-care reform. The Senate, controlled by Democrats but lacking a filibuster-proof majority, declined to act on the bill.

For opponents of addressing climate change, including fossil-fuel companies, the moment injected new energy into the fight. By 2009, as Gallup’s polling shows, acceptance of the changing climate began to sink. The political will had eroded. The legislation that passed the Democrat-led House got looped into the anti-government backlash that embodied the tea party movement. If there was still political will among Republican elected officials to address climate change, the base had made that a near impossibility.

Over the years that followed, that fight was reinforced by Fox News. A 2014 study by the Union of Concerned Scientists found that Fox News’s coverage in 2013 was mostly misleading, in large part by understating the reality of climate change. (In a now-familiar pattern, the study also found that much of the misinformation on CNN was driven by televised debates that included individuals committed to undercutting climate science.)

(Union of Concerned Scientists)

This was the same track that Trump followed.

In late 2009, as the United Nations was discussing climate change at a conference in Copenhagen, business leaders in the United States signed a letter arguing that the government should invest in clean energy with the goals of spurring innovation, leading the global market on clean energy and “reducing the harmful emissions that are putting our planet at risk.” Among the signatories were Trump and his three oldest children, all executives at the Trump Organization.

The extent to which that reflected Trump’s personal beliefs is subject to debate, certainly, but the organization itself saw utility in joining the consensus.

A few months later, Trump was toeing his now-established line in a now-established format: talking to Fox News host Neil Cavuto. A number of companies — including several major oil companies — withdrew from a climate-action group, reflecting, in part, the improved political climate for avoiding action on global warming. Trump explained why he agreed.

“Well, I don`t blame them,” he said. “They probably see the email that was sent a couple of months ago by one of the leaders of global warming, the initiative, and almost saying — I guess they’re saying it’s a con. And they see things like that. They see the fact that, in Washington, where I`m building a big development, nobody can move, because we have 48 inches of snow, and the snow is not melting because it’s so cold. And, in New York, we have had the coldest winter on record."

That email to which Trump was referring was any of a number stolen from a climate research team at a British university. The internal discussions of the scientists were presented as evidence that the issue of climate change was being intentionally overstated, but the emails did nothing to undercut the scientific consensus on the warming climate. The stolen emails became part of the political debate, severely damaging public perceptions.

This may sound familiar.

Trump’s overlap with politics was often marked by his echoing of popular opinion, particularly within the Republican base. His views on the war in Iraq mirrored public opinion as the conflict unfolded. His views on a number of other subjects, including climate change, have mirrored the consensus reflected on Fox News — consensus he helped form with his regular appearances on the network starting in 2011.

Gallup’s 2018 polling shows that Republicans have again moved away from belief that the effects of climate change are being felt, a move that Gallup says Trump “may have contributed to . . . by reversing a number of government actions to address the issue."

But that fervency by Trump may simply be the now-familiar fervency he shows for taking actions as president that were ones his base supported on the campaign trail. Trump’s been a hard-right conservative on many of the decisions he’s made, an effort to keep his base close. His climate moves may be affecting how the base views the issues, but it’s likely that his moves also reflect what his base wants to see.

This, too, didn’t start with Trump. In 2012, even Mitt Romney — who as governor of Massachusetts implemented a climate-change plan and excoriated fossil-fuel-burning power plants — felt compelled to solidify his base by rejecting the idea of acting on climate change. He mocked Obama’s climate-change advocacy using much the same rhetoric as Trump eventually would.

Trump’s embrace of what the base wanted to hear was more robust, more honest and more expansive. But over the course of the past decade, Trump followed the party lead on climate. He didn’t drive it.