A spokesman for Harper told AFP he will travel to Copenhagen for the December 7-18 climate talks, but a travel date has not yet been set.

The announcement marks a sudden reversal for Harper one day after US President Barack Obama said he would attend the conference.

Until now, Environment Minister Jim Prentice was expected to represent Canada at the talks.

However, with Obama now going and Ottawa's past insistence that Canada's climate change plans are inextricably linked to US actions, it appears Harper would have to go to Copenhagen.

Obama is to address the meeting in Copenhagen on December 9, the day before he heads to Oslo to receive the Nobel Peace Prize.

His administration will offer to curb US emissions by 17 percent from 2005 levels by 2020 -- less than calls by the European Union, Japan and UN scientists but the first numbers put on the table by the world's largest economy.

Earlier, societies representing 3,000 Canadian scientists pressured Ottawa in an open letter to seek a "rapid and adequate" response to climate change at upcoming international talks.

Canada sees a 20-percent reduction of CO2 emissions by 2020 compared to 2006, equivalent to a fall of three percent from a 1990 benchmark required by the Kyoto Protocol -- which Canada ratified but then refused to implement.

Its current CO2 emissions, however, are up more than 35 percent from 1990 levels.

Canada has been viewed internationally as a climate change laggard, appearing to try to scuttle efforts at securing an international pact to cut global CO2 emissions in order to protect its heavily US-reliant economy.

Canadian companies feared a trade disadvantage since US companies were not bound by the Kyoto Protocol, and the two nations are the world's largest trading partners.

In Copenhagen, "the eyes of the world will be on Canada," its scientific community wrote in an open letter. "We... urge the government to negotiate an outcome that will rapidly and adequately address climate change."

"We must act responsibly. We must act now. We must act in concert with other industrialized nations," they said, noting that "Canada is one of the largest per-capita greenhouse gas emitters."

The letter was signed by the heads of the Canadian Meteorological and Oceanographic Society, the Canadian Society of Zoologists, the Canadian Geophysical Union, the Canadian Society of Soil Science and the Canadian Association of Physicists.

Their member scientists warned of a looming loss of summer ice in the Arctic Ocean, more melting of glaciers and permafrost, increased evaporation from lakes and wetlands, severe urban heat waves, more forest fires, and disruptions in agricultural, forest, and energy production.

A public advisory group echoed their concerns, saying in a report that Canada is not prepared to cope with the devastating impact of climate change on its Arctic roads, buildings, energy and other infrastructure.

The National Round Table on the Environment and the Economy warned winter roads melting earlier in the spring could force northern communities to airlift supplies while melting permafrost could destabilize foundations for buildings.

As well, increased snowfall and changing ice conditions will add stress to buildings, and energy and communications infrastructure that were built for different snow and ice situations.

Permafrost degradation could also undermine Arctic airport runways and roads, and storm surges put coastal communities at risk and may require relocation of infrastructure away from shores, said the report.