When Trump's former environment adviser, until the president's inauguration this month, took to a stage in Brussels on Wednesday and called climate experts "urban imperialists", a rebuke from Britain's former energy minister drew applause from the crowd packed with EU officials.
But with fault lines over Brexit, dependence on Russian energy, and protecting industry threatening the bloc's own common policy, some EU diplomats worry Europe is too weak to lead on its own in tackling climate change.
Instead, they are pinning their hopes on China, concerned that without the backing of the world's second-biggest economy support for the global pact to avert droughts, rising seas and other affects of climate change will flounder.
"Can we just fill the gap? No because we will be too fragmented and too inward looking," one EU official, involved in climate talks, told Reuters. "Europe will now be looking to China to make sure that it is not alone."
The EU's top climate diplomat Miguel Arias Canete will travel to Beijing at the end of March, EU sources said. Offering EU expertise on its plans to build a "cap-and-trade" system is one area officials see for expanded cooperation.
Enticed by huge investments in solar and wind power in economies such as China and India, Germany, Britain and France are seeking closer ties to gain a share of the business.
But hurdles stand in the way of an EU clean energy alliance with China after the two sides narrowly averted a trade war in 2013 over EU allegations of solar panel dumping by China.
"We need to embrace the fact that China has invested very heavily in clean energy," Gregory Barker, climate change minister to former British Prime Minister David Cameron, told Reuters on the sidelines the environment conference in Brussels organized by conservative politicians.
"If America won't lead then it's clear that China will."
But despite Beijing's green policy drive, propelled by domestic anger over smog and the environmental devastation wrought by rapid economic growth, some EU officials are skeptical it can pull as much weight as the United States on climate issues.
"We will make a lot of noises (about allying with China), but let's be honest we lost an ally — a major one," a senior EU energy diplomat said, speaking on condition of anonymity. "China's biggest issues are domestic ... It's clean water, air and food."
Read more at Faced with U.S. Retreat on Climate, EU Looks to China