April 2 (Bloomberg) -- United Nations scientists have ``seriously'' underestimated the need for new technologies to reduce carbon-dioxide emissions and avoid the worst effects of global warming, U.S. researchers reported in the journal Nature.

The UN Intergovernmental Panel on Climate Change was probably mistaken when it forecast that global carbon emissions will grow more slowly than economies over the next century, wrote researchers Roger Pielke, Tom Wigley and Christopher Green, in a preview of the next edition of Nature.

While economic growth outpaced the increase in global- warming gases over the last few decades, that reversed in 2000 with the resurgence of developing economies such as China, said Pielke, a researcher at the University of Colorado and the lead author of the study, in an interview.

Assuming that the ratio, or carbon intensity, will continue to fall may dull the sense of urgency and make it more difficult for nations to reach their emissions targets, Pielke said.

``The world is in fact emitting more carbon dioxide at a rate faster than economic growth,'' Pielke said. ``The sorts of policies that are being discussed around the world here in the U.K., in the U.S. -- there's a good possibility they're not up to the challenge of stabilizing emissions.''

Nations set a deadline of less than two years to negotiate a replacement for the Kyoto Protocol, a treaty that requires developed countries to cut greenhouse-gas emissions blamed for global warming. The Kyoto accord expires in 2012. Governments worldwide are considering restrictions on industries including the automobile, power generation and airline sectors as well as support for renewable energy to cut carbon emissions.

To contact the reporter on this story: Jeremy van Loon in Berlin at jvanloon@bloomberg.net.

Last Updated: April 2, 2008 13:00 EDT