Former U.S. vice-president Al Gore speaks to the Millennium Summit on Thursday. (Ryan Remiorz/Canadian Press)

The United States deserves much of the blame for the failure of the Copenhagen climate summit after it turned its back on a little-known offer from China, former U.S. vice-president Al Gore said Thursday.

Gore offered a post-mortem of the summit at an international conference in Montreal, during which he revealed the Americans ignored a proposal from China in the days leading up to the December meetings.

Last fall, the U.S. Senate avoided passing sweeping environmental reforms that would have included a law to drastically cut the country's greenhouse gas emissions.

According to Gore, that sent the wrong signal to a potential ally heading into the climate talks.

"China had sent word through private channels to the U.S. that if the U.S. passed a law requiring a reduction of emissions below the 1990 levels then China would lean forward and help get a meaningful binding treaty," he told an audience of several hundred people.

"But the Senate failed to act and so President Obama was forced to go to Copenhagen without anything to put on the table."

The Copenhagen summit ended with a watered-down agreement by hundreds of countries to "take note" of the need for action on climate change, frustrating many environmentalists.

Gore's comments in Montreal will challenge the interpretation of several observers who blamed China for the failure to reach a binding accord.

He said following the Americans' refusal to ratify the Kyoto Protocol, the international community needed to see concrete action from Washington to prove it was serious about tackling climate change.

"When the Senate failed, then China balked and the rest of it unravelled to the point where they got a politically binding agreement but no more," Gore said. "There was some progress, but not nearly enough to call it a success."

Some U.S. senators have since overhauled the legislation that failed to pass last year. They will unveil a series of compromise reforms in Washington next week that Gore says stand a greater chance of becoming law.

Moral debate

In his speech to the conference, which centred on the United Nations' Millennium Development Goals, Gore sought to make the link between poverty and climate change.

It represented an expansion of the Nobel laureate's more scientific arguments about the urgency of dealing with climate change.

The science of climate change has faced an unprecedented attack in recent months after several errors were discovered in estimates by the U.N. Intergovernmental Panel on Climate Change, the group with which Gore shared the 2007 Nobel Peace Prize.

Gore himself appeared to back away from earlier warnings the summer Arctic ice cap could disappear by 2014, saying Thursday it was "a matter of a decade or so."

Instead he focused on the moral dimension of the climate change debate, which he called "a challenge to our understanding of who we are as human beings."

Gore ended his speech sounding more like a preacher than a scientist.

"Rally the forces of conscience and common sense to solve this crisis," he implored his audience.