The EU has formally adopted climate change targets for December's Paris conference including a 40 per cent cut in emissions by 2030, climate commissioner Miguel Arias Canete says.

The targets were agreed on by leaders of the 28 European Union member states at a summit in October, but the confirmed benchmarks have now been officially sent to the UN, Canete said on Friday.

"There is an agreement, but it was not an easy matter," Canete said after a meeting of EU environment ministers in Brussels.

French minister Segolene Royal added: "Europe is the first continent to send its contribution, as was asked by the United Nations,"

The offer of the EU, which is responsible for nine per cent of global emissions of greenhouse gases, was sent to the UN secretariat, Canete said.

Countries have until March 31 to announce their commitment to cutting greenhouse gas emissions.

The EU, which when taken together is the world's biggest economy, says it will cut greenhouse gas emissions by at least 40 per cent compared to 1990 levels.

The United States, which accounts for 12 per cent of global emissions, announced its intention to reduce them by 26-28 per cent in 2025 compared with their level in 2005.

China has set a target date of about 2030 for its emissions to peak.