Kim Hjelmgaard

USA TODAY

One day after the United States said it would slash carbon emissions from existing power plants by 30% below 2005 levels, China, the world's largest emitter of greenhouse gases, said it would set an absolute cap on its emissions by 2016.

The announcement comes ahead of the start of U.N.-sponsored climate talks in Bonn, Germany, on Wednesday. The steps being taken by the world's top two polluters are important announcements that signal positive steps in addressing the planet's changing climate, Christiana Figueres, the U.N.'s top climate official, told USA TODAY on Tuesday.

However, she cautioned, "We need ever higher ambition by all nations in the run-up to the U.N. climate convention meeting in Paris in 2015 — ambition that can match emission reductions and support for adaptation in vulnerable countries and communities with the sobering scientific reality."

In Paris, the U.N. is seeking to adopt a legally binding agreement on emissions that will cover all nations.

The new pledge by China was made at a climate conference in Beijing by He Jiankun, chairman of China's Advisory Committee, according to Reuters. On Monday, the Obama administration unveiled aggressive plans to target a low-carbon future for the USA.

In a statement on Sunday, Figueres praised the proposal by the Environmental Protection Agency that ultimately works to address climate change by pushing for a more diversified energy mix: "I fully expect action by the United States to spur others in taking concrete action — action that can set the stage and put in place the pathways that can bend the global emissions curve down in order to keep worldwide temperature rise under 2 degrees Celsius this century," she said.

Connie Hedegaard, the EU's climate commissioner, speaking of the EPA draft rule, which won't come into effect for at least two years, said: ''This proposed rule is the strongest action ever taken by the U.S. government to fight climate change."

China and the USA are the world's top carbon dioxide emitters followed by the 28-country bloc that forms the European Union. On Tuesday, the EU confirmed that its carbon emissions have fallen to 19.2% below 1990 levels.