Trump was scheduled to attend Monday's session on climate, biodiversity and oceans at the G-7 summit in Biarritz , but didn't. French President Emmanuel Macron, the summit host, said Trump's aides were there instead.
Trump is a climate change skeptic who once had claimed it's a hoax that was invented by the Chinese. His decision to withdraw the United States from the 2015 Paris climate accord has severely damaged global efforts to reduce emissions.
Trump started the morning behind schedule, and held one-on-one meetings while others were in the climate discussions. However, one of his interlocutors, German Chancellor Angela Merkel, managed to make it to the climate meeting.
Trump then met with India's Prime Minister Narendra Modi, where he was asked about attending the climate session. Trump said it would be his next stop and that he wants clean air and water.
But he never showed up.
Macron shrugged off Trump's absence, saying it wasn't his goal to try to persuade Trump to rejoin the climate accord. "You can't rewrite the past," Macron told reporters.
But Macron said he and Trump had a "long, rich and totally positive" discussion on the Amazon fires and an international effort to invest in "re-foresting" the area.
U.N. Secretary General Antonio Guterres - who attended Monday's climate talks - expressed hope that Americans themselves would help fight climate change even if their president doesn't.
"I am very optimistic about American society and its capacity to deliver in relation to climate action," he told reporters afterward. "What matters here is to have a strong engagement of the American society and of the American business community and the American local authorities."
David McHugh in Biarritz, France, contributed to this report.