Group of Eight leaders have agreed on a plan calling for "substantial cuts" to greenhouse gas emissions, German Chancellor Angela Merkel announced Thursday.

While few details of the agreement have been released, Merkel, at the G8 summit in Heiligendamm, Germany, said the goal is to cut greenhouse gas emissions in half by 2050.

G8 Leaders gather outside between meetings in Heiligendamm, Germany on Thursday.
(Herbert Knosowski/Associated Press)

Canadian Prime Minister Stephen Harper said the plan is an important step. Later back in Canada, though, the Opposition expressed skepticism.

"What's been agreed for the first time is that we must have targets and there must be global targets," Harper told reporters after his discussions with the other G8 leaders.

"I think it's a major step forward. If we can keep the momentum going, I think we're moving in the right direction."

Leaders at the summit agreed to kick-start talks to reach a successor to the Kyoto Protocol by 2009, beginning with a climate change conference in Bali in December.

Kyoto, which requires signatories to reduce greenhouse gas emissions to five per cent below 1990 levels by 2012, expires in five years.

The declaration falls short of an ironclad commitment to emissions cuts, saying only that the world's biggest greenhouse gas emitters should "seriously consider" following the European Union, Canada and Japan in seeking to halve their output by 2050.

European countries had been calling for a 50 per cent cut in world emissions below 1990 levels by 2050. A Canadian environment bill that remains in limbo after criticism from opposition leaders and environmentalists calls for an emissions cut of between 45 per cent and 65 per cent by 2050.

Harper said there needs to be extensive discussion before settling on finite global targets. He said targets chosen too hastily do not work, citing the Liberal government's commitment to the Kyoto Protocol in 1998. 

"We committed to targets without thinking those targets through 10 years ago and then we were unable to reach them," he said.

"When others [G8 leaders] say we want a full discussion before we determine what reasonable targets are, I think that's something we have to be flexible on." 

Merkel had pushed for binding resolutions on emissions cuts, but U.S. President George W. Bush proposed countries instead set a long-term goal and decide for themselves how much to do to meet it.

Separated by 2 degrees

The agreement does not commit to Merkel's "two-degree" goal to cap a rise in the Earth's temperature to within two degrees.

Still, Merkel said leaders took the tough step of declaring emissions have to be cut in half.

"No one can escape this political declaration. It is an enormous step forward," she told reporters.

She said the agreement came after many rounds of talks and negotiations on climate change, one of the most contentious issues at the summit.

Last week, Bush called for a meeting of major greenhouse gas-emitting countries by the end of the year and a global emissions target by 2008.

Canada's Opposition attacks the plan

Federal politicians in Canada gave their takes on the plan in the House of Commons.

"The bar has been set so low that this so-called agreement does not even reflect what is really necessary to fight against climate change," Liberal Leader Stéphane Dion said.

Fellow Liberal MP Michael Ignatieff called it "an agreement that will do nothing.

"Like a child crossing his fingers behind his back, the prime minister committed to stabilize emissions overseas while his plan at home will allow emissions to continue to rise beyond 2020."

With files from the Associated Press