The European Union is expected to release details of a carbon border adjustment in June. The adjustment would take effect no earlier than 2023.

A border adjustment is a tariff to ensure that products made in other countries that are not making the same effort as the European Union to reduce carbon emissions do not have an advantage over domestically-produced goods because of lower manufacturing costs.

The United Kingdom is considering a carbon tariff to protect British industry.

US climate envoy John Kerry discouraged European leaders in March from adopting such a proposal. Kerry said it should be adopted only as a “last resort” and not before the United Nations global climate conference in Glasgow in November.