At 19, Glasgow college student Ross Hamilton doesn’t think highly of world leaders — “they chat a lot of” nonsense — or expect them to accomplish anything on a problem he cares deeply about, climate change.

But there is one former world leader Hamilton trusts, at least enough to join several hundred Glasgow college students crowding outside their college in the dark Monday in hopes of a glimpse of him: Barack Obama. “I’ve always liked him. I feel as if he’s pretty honest.”

The former U.S. president, one of the leaders responsible for the 2015 Paris climate accord, came to the U.N. global climate talks in Glasgow, wielding his cross-generational appeal to urge frustrated climate activists to stay in the fight. Even five years out of office, and now 60, Obama still claims a rapport with liberal and moderate young people in a way that President Joe Biden, 78, might not be able to pull off.

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Inside the glass-fronted building where Hamilton and other students of Glasgow’s Strathclyde University were waiting for him to emerge, Obama was sitting around a table with a dozen climate advocates from around the world, hearing them out and encouraging them.

Obama was in shirtsleeves and tieless, his hair whiter than during his presidency.

“The success of the movement shouldn’t be diminished even if some of the outcomes” have fallen short, Obama told the gathering of climate-focused people in their 20s and 30s. They included a lawmaker, a filmmaker, legal advocate, private and public businesspeople, foundation leaders and heads of activist groups.

“The question is, where are the countries that really met our expectations? And it turns out those are the places where there was pressure, where there was political mobilization, where there were activists,” Obama told them.

It’s all “going to depend on you guys to apply it,” he added.

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Obama as president introduced programs to move the U.S. more toward renewable fuel and away from coal, although President Donald Trump rolled back most of them.

Not all younger people are Obama fans.

Ugandan climate activist Vanessa Nakate tweeted Monday that she was 13 when the United States, under Obama’s leadership, was among rich nations promising $100 billion a year to poor countries to help them fight and cope with warming, but said those nations broke the promise.

Nakate told The Associated Press on Monday that she wasn’t attacking the former president, “but that is me speaking the truth.”

“This money was promised, but it hasn’t been delivered,” Nakate said.

Especially in Europe, young activists are credited with pressuring governments to confront climate change. Most famously, teenager Greta Thunberg in 2018 launched a climate movement that has since drawn hundreds of thousands to weekly protests to demand governments end their dependence on coal, natural gas and oil.

After the Paris deal, Glasgow was billed as the talks where roughly 200 governments would put the accord into action.

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Last Friday, Thunberg, now 18, branded the talks a “failure” after their first of two weeks. Speaking to tens of thousands of young climate demonstrators protesting Friday in the summit’s host city, Thunberg said national delegations at Glasgow were carving out loopholes for every pledge and “greenwashing” their own countries’ emissions.

Young people were finding it hard to believe a climate movement that had mobilized so many could fail, Luisa Neubauer, a leader of Thunberg’s movement in Germany, told Obama.

Neubauer told Obama she feared disillusionment was undermining peoples’ faith in democracy, “as people, especially activists, lose confidence in their governmental pledges, in what often turns out empty promises, in the lack of honesty about past failures.”

Stay the course, Obama told climate activists.

“Don’t think that you can ignore politics,” Obama said earlier, in a speech at the talks site that saw the former president draw short standing ovations.

“You don’t have to be happy about it, but you can’t ignore it. You can’t be too pure for it,” Obama said, devoting much of his speech to the young activists he said he came to Glasgow to be with it.

“It’s part of the process that is going to deliver all of us,” he said.