President Trump holds up an executive order on “energy independence,” eliminating Obama-era climate change regulations, during a signing ceremony at EPA headquarters. (Carlos Barria/Reuters)

President Trump’s executive order rolling back President Barack Obama’s signature anti-global-warming measure stopped short of withdrawing from the historic Paris climate accord — but raised international concerns Tuesday about whether the United States will do its share to fight the global threat.

Europe’s top climate official, European commissioner Miguel Arias Cañete, expressed “regret” about Trump’s executive order rolling back what he called the “main pillar” of U.S. climate policy, the Clean Power Plan, in a statement to The Washington Post.

“Now, it remains to be seen by which other means the United States intends to meet its commitments under the Paris Agreement,” said Cañete.

Despite all the current geopolitical uncertainties, the world can count on Europe to maintain global leadership in the fight against climate change. We will stand by Paris, we will defend Paris, and we will implement Paris.”

The words of Cañete, one of the most prominent global diplomatic figures yet to comment on Trump’s move, signal how the president’s executive order eviscerating Obama’s climate plan is raising international concerns, and they further suggest that the country could be left isolated as other nations push forward to curb emissions.

Trump’s executive order stopped short of withdrawing from the Paris climate accord — which Trump had vowed to “cancel” during the campaign — but it’s far from clear how the United States will now be able to meet its commitments under the 2015 agreement, in which more than 195 governments pledged to take action to hold the planet’s warming “well below” a danger zone of 2 degrees Celsius.

Those concerns about U.S. climate commitments under a Trump presidency could come up in May when diplomats gather for a working group meeting on the Paris climate agreement.

“We will have to wait to see how the Trump administration explains its actions to other countries when they meet in Bonn, Germany, in May,” said Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment at the London School of Economics and Political Science.

However, according to the terms of the Paris agreement, the United States will not be called to account for its emissions reductions commitments until 2023, Ward said.

The Paris agreement depended on individual commitments from each country to reduce emissions. The Clean Power Plan, which Trump’s order seeks to rescind, was a core part of the U.S. commitment to reduce greenhouse gas emissions 26 percent to 28 percent below their 2005 levels by 2025.

Under that plan, the United States pledged to cut 28 percent to 29 percent of the country’s carbon dioxide emissions from the electricity sector by 2025 — one of the main sources of these emissions.

Already, allies and nations that have been pushing for — or taking — strong action on climate change are concerned.

“The reality is that the Paris Agreement’s commitments alone do not go far enough to limit warming,” said Thoriq Ibrahim, energy and environment minister for the Maldives and chair of the Alliance of Small Island States, a key player in international climate negotiations, in a statement to The Post.

“All countries need to do more and do it faster. The good news is that we are already witnessing a dramatic transition to renewables in global energy markets. The trend appears unstoppable, but small islands would certainly feel better about our chances if the world’s biggest economy stayed on track to meet its targets.”

Jiang Kejun, a researcher at the Chinese government think tank Energy Research Institute, said that Trump’s decision to scrap the Clean Power Plan would be “a bad signal” and that Beijing was watching closely.

“It’s … rather negative news,” Jiang said, but insisting that it’s not necessarily impacting China in a negative way. “China’s general policy will not retreat. In fact, it might have to do more and reach out to more partners elsewhere,” such as the European Union and Japan.

The Obama administration also heavily courted another major player, India — which is projected to see the largest growth in energy demand in coming years — seeking climate change collaboration. It’s unclear how the Trump administration’s rollback could affect that country’s outlook.

Scott Pruitt, the Environmental Protection Agency’s administrator, seemed to suggest on Sunday that there was no contradiction between the U.S. backing away from the Clean Power Plan and remaining in the Paris agreement.

“The Clean Power Plan is not tethered to the Paris accords,” Pruitt said on ABC. He also said that overall U.S. emissions have been declining, “largely because of innovation and technology in the coal sector and the natural gas sector.”

However, while emissions in the United States could continue to decline because of market forces and coal-to-gas switching, and a growth in renewable sources of electricity, it is hardly assured that will continue.

Without regulations in place — or with weaker ones — the United States could conceivably switch back to burning more coal if natural gas prices rise enough. The U.S. Energy Information Administration is already predicting a slight uptick in coal burning in 2017, due to higher natural gas prices.

Overall, estimates vary on where the United States will be in 2025 or 2030 without the Clean Power Plan. One study by the Rhodium Group found that the Trump executive order would mean that the United States would see its emissions decline only 14 percent below their 2005 levels by 2025, as opposed to a 21 percent drop without the order.

Another recent report from the Carbon Tax Center found that by the end of 2016, “the U.S. electricity sector will have reduced its emissions of carbon dioxide by 27 percent since 2005, thus achieving more than four-fifths of the 2030 carbon-reduction goal set by the Obama Administration’s Clean Power Plan.” In other words, emissions are falling fast, even without the plan yet in place.

Observers of climate politics don’t think the United States’ backsliding on carbon cuts will necessarily derail the overall Paris process — even though U.S. diplomacy was critical to reaching an agreement.

“This will raise a level of concern with other countries,” said David Waskow, director of the International Climate Initiative at the World Resources Institute. “At the same time, they’re going to keep going with their own actions, and they have their own domestic reasons to keep moving forward.”

Others thought Trump’s executive order would be seen as a sign that the United States is retreating from global climate leadership.

“The rest of the world is likely to look on these actions more in sorrow than in anger — as a clear signal that Washington is abandoning its leadership role on climate, but not a threat to the growing momentum for global climate action,” said Nathaniel Keohane, who heads the global climate program at the Environmental Defense Fund. “American leadership was critical to securing the Paris climate accord — but with that agreement in force, the rest of the world has embarked on a low-carbon path regardless of what Washington chooses to do. If the U.S. steps back, China will be happy to step forward.”

The Trump executive order could encourage other countries to backslide on their commitments — such as Brazil, another major global emitter, mainly because of deforestation. Brazil’s deforestation rates have been rising again, due to an apparent inability to enforce prohibitions on chopping down or burning large swaths of the vast Amazon rainforest.

Another consequence of the decision for the United States, Waskow said, would likely be a loss of influence as climate change becomes more and more central to negotiations between countries. “I think what will happen is that over time, countries will continue pressing forward, in venues like the G7 and the G20, and the United States will become more and more isolated if it doesn’t get on board,” he said.

— Simon Denyer and Luna Lin contributed to this report.