LONDON — Global emissions of carbon dioxide are increasing three times faster than scientists previously thought, with the bulk of the rise coming from developing countries, an authoritative study has found.

The increase in emissions of the gases responsible for global warming suggests that the effects of climate change to come in this century could be even worse than U.N. scientists have predicted.

The report, by leading universities and institutes on both sides of the Atlantic, will create renewed pressure on G–8 leaders who are meeting this week in Heiligendamm, on Germany’s Baltic coast. Top of the agenda are proposals by Germany’s Chancellor Merkel to halve global emissions by 2050.

There were violent clashes over the weekend in the nearby city of Rostock between police and protesters during a march by tens of thousands demonstrating about the summit.

The latest study was written by scientists from the Oak Ridge National Laboratory in America, the University of East Anglia, and the British Antarctic Survey, as well as institutes in France and Australia.

It shows that carbon dioxide emissions have been increasing by 3% a year this decade, compared to a 1.1% a year rise in the 1990s. Three quarters of this rise came from developing countries, with a particularly rapid increase in China. The rise is much faster than even the most fossil-fuel intensive scenario developed by the Intergovernmental Panel on Climate Change during the 1990s.