A major new United Nations report shows global scientists are more convinced than ever that human activity is causing climate change, the Toronto Star has learned.

The rate of warming between now and 2030 is likely to be twice that of the previous century, it says.

A new report concludes that most of the global warning since the middle of the last century has been caused by man-made greenhouse gases. (AP Photo)

The report, to be released in Paris Feb. 2, should all but end any debate on climate change and compel governments and industries to take urgent measures to deal with it, scientists say.

"It is very likely that (man-made) greenhouse gas increases caused most of the globally average temperature increases since the mid-20th century," states the report of the Intergovernmental Panel on Climate Change.

In the clinical language of science, it paints a stark picture of the effects of greenhouse gas emissions:

Be afraid. Be more afraid.

FIVE MINUTES TO MIDNIGHT British scientist Stephen Hawking is seen during a press conference on the 'Doomsday Clock', a symbol of the risk of atomic cataclysm, at the Royal Society in London, Wednesday, Jan. 17, 2007. Hawking described climate change Wednesday as a greater threat to the planet than terrorism. Hawking made the remarks as other prominent scientists prepared to push the giant hand of the Doomsday Clock, closer to midnight. (AP Photo/Lewis Whyld, PA) FIVE MINUTES TO MIDNIGHT Doves fly over the A-bomb Dome at Hiroshima's Peace Memorial Park during the 60th anniversary of the bombing that killed more than 140,000 people in 1945. The world inched closer to nuclear Armageddon on Wednesday, according to a group of prominent scientists who moved a Doomsday Clock two minutes nearer to midnight -- the symbolic end of civilization. (AFP/File/Yoshikazu Tsuno)

The clock – a symbol of the perils facing the human race – is expected to shift two minutes, from the current seven minutes to midnight to five, a figure the Bulletin would not confirm before its news conference today.

"This is a sober and highly alarming judgment by a group of people who are knowledgeable and experienced," said Nobel laureate John Polanyi, a faculty member in the University of Toronto's chemistry department.

"The most immediate hazard we face is also the most easily addressed, namely the thousands of nuclear-armed weapons aimed at Russia and the United States, and left pointlessly in a state of high alert. The fact that they are is an appalling failure to step back from the brink."

The clock, which hangs in the University of Chicago, was first set 60 years ago to focus on the danger of nuclear weapons. But for the first time it will take into account the perils posed by global warming, which has sparked renewed interest in building nuclear power plants.

The Bulletin of the Atomic Scientists was founded by former Manhattan Project scientists who turned against nuclear weapons after developing the first atomic bomb.

"The major new step reflects growing concerns about a `Second Nuclear Age' marked by grave threats, including: nuclear ambitions in Iran and North Korea, unsecured nuclear materials in Russia and elsewhere, the continuing launch-ready status of 2,000 of the 25,000 nuclear weapons held by the U.S. and Russia, escalating terrorism and new pressure from climate change for expanded civilian nuclear power that could increase proliferation risks," said a statement released before a news conference today.

Bears have stopped hibernating in the mountains of northern Spain, scientists revealed yesterday, in what may be one of the strongest signals yet of how much climate change is affecting the natural world.

In a December in which bumblebees, butterflies and even swallows have been on the wing in Britain, European brown bears have been lumbering through the forests of Spain's Cantabrian mountains, when normally they would already be in their long, annual sleep.

European brown bears in Spain.

But many of the 130 bears in Spain's northern cordillera - which have a slightly different genetic identity from bear populations elsewhere in the world - have remained active throughout recent winters, naturalists from Spain's Brown Bear Foundation (La Fundación Oso Pardo - FOP) said yesterday.