World leaders insist President Trump’s decision to withdraw the U.S. from the Paris agreement will not deter other nations from carrying out their commitments. But the departure of America creates new challenges for global efforts to tackle climate change.

Most of the world responded last week to Donald Trump’s Rose Garden announcement that the United States was withdrawing from the Paris climate accord with a robust “Shame on you; but it won’t change our plans.” But the actual fallout is likely to be more complex. Already right-leaning politicians in Germany and Australia are calling for domestic U-turns on climate policy. And in Russia, Vladimir Putin hinted that without a deal to assuage Trump, he might not ratify the accord.

Meanwhile, an analysis released last week found that European greenhouse gas emissions rose in 2015 for the first time in five years. And a new study this week warns that even China, which has taken the geopolitical high ground since President Trump’s pullout, has a huge amount of wiggle room in its commitments.

Other analysts are warning that many developing countries — including the world’s fourth biggest emitter, India — made their Paris promises contingent on funding from rich nations, with the U.S., until now, expected to be the biggest contributor. Trump’s announcement — which left the U.S. joining just two nations, Syria and Nicaragua, in rejecting Paris — was political theater that played to his core supporters. But for analysts of the arcane political process of fighting climate change, it was puzzling, particularly when he added that he might be willing to negotiate a return to the accord under different conditions. The national emissions commitments made in Paris were voluntary and remain so, analysts pointed out. The White House could have simply announced it was changing its commitments. “Withdrawing and then re-entering under different terms would in effect be identical to revising the U.S. [pledges] — something the agreement specifically allows,” said climate scientist Myles Allen of Oxford University. Trump’s announcement also confounded many of the top executives in the U.S. fossil fuel industry, who had counseled him to stay in the accord to increase the U.S.’s leverage in the run-up to the 2018 review of Paris commitments. Darren Woods, who succeeded Trump’s Secretary of State Rex Tillerson as CEO of Exxon, wrote to the president last month saying America was “well positioned to compete” in a low-carbon world and recommending the U.S. maintain “a seat at the negotiating table to ensure a level playing field.”

The concern is whether the world outside Trump’s Washington will prove as determined to abide by the Paris accord as some analysts claim.

Yet in a suddenly topsy-turvy world, some hawks for action on climate almost cheered Trump’s statement. Environmental economist Paul Ekins of University College London says it might be better to have the U.S. out since, “with the U.S. at the table, there is a real risk that it would oppose ambitious action by other countries at every turn.” But the real concern now is whether the world outside Trump’s Washington will prove as determined to abide by and strengthen the Paris accord as some analysts claim. In the hours after Trump’s announcement, the bluntest rebuke from a world leader came from German Chancellor Angela Merkel. “We have to protect Mother Earth,” she said. Few doubt her sincerity. Her attachment to the climate cause goes back to her days as a young environment minister in 1995, when she chaired negotiators on the Berlin Mandate, which led to the Kyoto Protocol two years later. But she will need her steel. She has federal elections coming in three months, and some in her Christian Democratic party take a different view. The right-wing Berlin Circle, which previously lobbied successfully against her open-door policy on refugees, responded to Trump’s exit by rejecting the Paris deal as unrealistic and calling for the abolition of Germany’s ambitious renewable energy targets. There may be stirrings in other countries too. Britain is electing a new government this week. It is likely to return to office Prime Minister Theresa May, whose enthusiasm for climate action is lukewarm. Last week, she declined to sign the strong statement condemning Trump issued jointly by the leaders of France, Germany, and Italy. She said she had made her “disappointment” known privately. But Britain will need to reset its climate policy after leaving the European Union, and her Conservative Party includes many climate skeptics. Margaret Thatcher’s one-time finance chief Nigel Lawson, one of those skeptics, claimed that the Trump withdrawal would further increase the “huge” and “entirely unsustainable” difference in energy costs between the U.S. and Europe. The situation in Australia, which in Paris pledged a 26-28 percent cut in emissions from 2005 to 2030, is quite similar. The Liberal-led coalition government in Canberra this week reiterated its target was “reasonable and achievable,” but right-wing rebels, including former ministers, have called for withdrawal from the Paris agreement.

Chinese Prime Minister Li Keqiang (right) with European Council President Donald Trusk at a business summit in Brussels last week. EMMANUEL DUNAND/AFP/GETTY IMAGES

And Putin’s response added to the unease. He said that he would not “judge” Trump on the decision, but warned that “if such a major emitter as the U.S. is not going to cooperate entirely, then it won’t be possible to agree any deal in this area.” With Russia one of about 50 countries yet to ratify the Paris accord, that suggests, at the least, that Putin is in no hurry to enshrine it in Russian law. Myles Allen, of Oxford, said: “We need to think hard about how to make the agreement both more effective and more acceptable to nations with substantial fossil reserves — or the U.S. won’t be the last one to be taking this step.” By chance, the day after Trump spoke, leaders from the EU and China held a business summit at which they reaffirmed the Paris agreement. Miguel Arias Cañete, EU commissioner on climate action and energy, said afterward that the two powers “are joining forces to forge ahead on the implementation of the Paris agreement and accelerate the global transition to clean energy” by cooperating on issues such as emissions trading and clean technologies. The response, said Nick Mabey of the U.K.-based climate think tank E3G, “was the strongest bilateral statement on climate I have seen. President Trump has driven the EU and China together to write the rules for the clean economy.” Some are less keen to take China’s climate enthusiasm at face value. The country, which is currently responsible at least 23 percent of global emissions, has left itself a lot of flexibility in its commitments, according to Joeri Rogelj of the International Institute for Applied Systems Analysis in Austria. For instance, it agreed in Paris “to increase the share of non-fossil fuels in primary energy production to about 15 percent.” But, Rogelj said, “the share of non-fossil fuels can be calculated in different ways,” so the calculations used could alter China’s total emissions under its pledge by as much 30 percent. That may be overly gloomy. All the signs, says Bill Hare of the European think tank Climate Analytics, are that China will exceed its Paris targets without recourse to statistical sleight of hand. “Coal consumption in China has declined from 2013,” he says. If that trend continues, as seems likely, China “may already have peaked its CO2 emissions from energy use … much earlier than the ‘before 2030’ stated in Paris.”

The U.S. share of global emissions is down from 19 percent in 1997 to 13 percent today, but its energy policies still matter a lot.

That would be an impressive achievement. By contrast, even as President Barack Obama left office, the U.S. was not on track to meet its own pledge to reduce emissions by 26-28 percent from 2005 to 2025. The U.S. is not such a powerful force in driving climate change as it was two decades ago. Its share of global emissions is down from 19 percent in 1997 to 13 percent today, according to Hare. But its energy policies still matter a lot. Hare says the likely effect of Trump’s changes in energy policy would be to flatline U.S. emissions that would otherwise have fallen. That could, he calculates, add between 0.1 and 0.2 C to global warming by 2100.

Even so, many commentators think the biggest impact of the Trump statement will be on the actions of others. He will provide political cover for backsliding of targets. And by withholding money from the UN’s Green Climate Fund, he could send a chill over climate-friendly investments in dozens of countries. “Many developing countries made national emissions targets conditional on the availability of support, financial and technological,” said Rogelj. “The U.S. reversal of its commitment … can influence the ability of those countries to implement these conditional targets.” He estimates in a paper published this week that if those conditional pledges are abandoned, it could result in an increase in annual global emissions of between 1.0 and 2.7 billion tons of CO2 by 2030. Most of the international investment, intended to reduce emissions and help countries adapt to climate change, is expected to come from the private sector rather than governments. But even so, the U.S. was slated to pay $3 billion of the $10 billion in government funding by 2020. With only $1 billion paid, that looks a like a $2 billion shortfall. And with Washington reneging, others may drop out too, leaving many more questions about whether the money will come at all. Some argue that none of this matters as much as it appears. Action on climate change is now more about advancing technology and changing economics than diplomacy and politics. It is, in contrast to what Trump suggested in his announcement, no longer a zero-sum game of “burden sharing.” They maintain that falling prices of renewables, and the rise of smart technologies to make more efficient use of energy, are making old energy-generating technologies obsolete. According to an April report from the Center on Global Energy Policy at Columbia University, in the five years before the Paris accord was agreed, U.S. coal consumption fell 20 percent, and Trump’s efforts are unlikely to reverse that. And globally, starting in 2015, the majority of new electricity generating capacity has been from renewables.

Most observers see Trump’s announcement as an act of populist isolationism that is economically misguided and politically doomed.