Brussels — The European Union said Wednesday it would slash carbon emissions by 90% by 2040, in an agreement widely seen as a weakening of the 27-nation bloc's previous climate goals, after an overnight debate ahead of the U.N. climate conference in Brazil.

Hungary, Slovakia and Poland voted against the agreement, despite other nations agreeing to key compromises including allowing flexibility for member states to buy carbon credits internationally to reach their emissions targets and for the EU to reassess its climate policy depending on economic performance. The agreement also allows for postponing a new carbon trading plan covering transport and heating, a central demand of Poland.

Environmentalists criticized the deal for provisions that will allow the EU to buy carbon credits from

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