Across the Atlantic, US climate envoy John Kerry warned in March that the EU levy should be envisaged only as a last resort measure, saying: "It does have serious implications for economies, and for relationships, and trade."

Do not make the mistake of extending the carbon market to heating hydrocarbon fuel. We experienced it in France, it gave us the Yellow Vests," warned Pascal Canfin, the chair of the European Parliament's environment committee, who called the proposed reform "politically suicidal".