Prime Minister Stephen Harper will attend the Copenhagen climate change meeting next month after all, his office said Thursday — a day after saying he would not go.

Harper decided Thursday to attend the meeting to work on a new climate change agreement after the U.S. president and Chinese premier announced that they will show up, his spokesman said.

Canada has been strongly criticized internationally for reneging on the Kyoto climate protocol and for refusing to sign on to a new deal limiting greenhouse gases unless developing nations are included.

President Barack Obama will appear at the summit on Dec. 9 before heading to Oslo to accept his Nobel Peace Prize, according to a White House official.

At least 65 world leaders, including Chinese Premier Wen Jiabao, are expected to be in Copenhagen, but unlike Obama, most are expected to attend the final days of the conference, which runs Dec. 7-18. It's not clear when Harper will be present.

Ignatieff calls for cap and trade

Meanwhile, Liberal Leader Michael Ignatieff told a Quebec City audience Thursday that Canada must create a cap-and-trade system in which companies would make money by going green, and polluters would need to pay.

He said he hoped such a plan would fit into a global system, and work in conjunction with any plan set up in the U.S. But he said Canada should go ahead and create the system even before the Americans have established theirs.

Ignatieff also said he favoured using the stricter baseline year of 1990, favoured by most developed countries and the backbone of the international Kyoto accord, to calculate emissions cuts — while the Harper government prefers using 2006.

His plan would benefit provinces, like Quebec and Manitoba, that have already been working over the last decade and a half to reduce their emissions, Ignatieff said.

With files from The Canadian Press