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BONN, Germany — If world leaders are angry at the United States for rejecting the Paris climate change agreement, few at United Nations climate talks here are openly showing it.

Delegates from the largest industrial countries to the smallest island states are tiptoeing around the single largest topic of discussion here — the American retreat from leadership on climate change and the Trump administration’s moves to undermine domestic global warming policy and international climate diplomacy.

President Emmanuel Macron of France on Wednesday challenged Europe to “replace America” in financing the United Nations climate change science body, though he did not directly criticize President Trump’s decision to eliminate American contributions to it. The German chancellor, Angela Merkel, praised a coalition of American governors and mayors who, in contrast to the White House stance, are still working to reduce their greenhouse gas emissions.