99 per cent of our atmosphere is made up of two gases: nitrogen, at 78 per cent, and oxygen, at 21 per cent. They don’t really affect climate regulation.

The six trace gases that are blamed for global warming make up only 1 per cent of gases in the atmosphere. The gases, created mainly by human activities, are:

• Carbon dioxide
• Methane
• Nitrous oxide
• Sulphur hexafluoride
• Hydrofluorocarbons
• Perfluorocarbons

On Friday, May 4, a UN-led panel of climate change scientists made their case for quick action on reducing greenhouse gas emissions. Now, say several contributors to the report, it's up to policy-makers to follow through with solutions.

"We need to act now and set up a workable regulatory framework," said John Drexhage, a lead author of the Intergovernmental Panel on Climate Change's third report, which details strategies for mitigating the impact of climate change.

"More than stringent targets, what we need is a system that gets the ball rolling," said Drexhage, the director of the International Institute for Sustainable Development's climate change and energy program.

The summary of the third report makes the case that there are environmental, health and economic benefits to reducing greenhouse gases and says — contrary to the beliefs of some — that reducing the gases that lead to global warming will not trigger economic disaster. Stabilizing greenhouse gas emissions by 2030 could be accomplished at a cost of three per cent of global GDP or less, it says.

But it also says those goals, while achievable, might not be enough. A more stringent regime of stabilizing emissions by 2015 and reducing emissions by between 50 and 85 per cent by 2050 will be required to keep temperature increases from exceeding 2.4 C, it says. It's at temperature increases above the range of 1.5 C to 2.5 C where scientists predict the first wave of negative impacts on the planet, including increased extinction of species, coastal flooding and water shortages in arid regions.

The report also finds there is high agreement and ample evidence that health benefits from reducing air pollution caused by greenhouse gas could, in some cases, more than offset the economic costs of cutting emissions.

University of Toronto climate change expert Danny Harvey, another of the lead authors of the report that the summary was based on, said the findings are a wake-up call for those who think climate change policies are economically unachievable.

"There are a lot of people who say that if you start reducing emissions, you'll ruin the economy," Harvey told CBC News Online. "But these are just scare tactics."

The Intergovernmental Panel on Climate Change has issued summaries of three reports this year, detailing the science, the consequences and the potential solutions to climate change. Here is a summary of the findings of the first two reports:

• Working Group I: The Scientific Basis

  The first IPCC report said global warming was "unequivocal" and that it was very likely caused by man-made greenhouse gas emissions, mostly from the burning of fossil fuels. It predicted average worldwide annual temperatures will increase between 1.8 C and 4 C over the next century and that sea levels will rise between 18 and 59 centimetres over the same time.

• Working Group II: Vulnerabilities and Adaptation

  The second IPCC report said the planet faced dire consequences if temperatures were allowed to rise at current levels and said humans must learn to adapt to changing climate conditions. According to the report, up to 30 per cent of the Earth's species face an increased risk of extinction if average global temperatures exceed 1.5 C to 2.5 C, coastal regions face heightened threats from flooding and the erosion of coastlines, and areas suffering from water shortages will become even dryer, leading to increased risks of hunger and disease.

Among the recommended strategies for reducing emissions are improving energy efficiency in buildings, switching from coal-fired power to renewable energy sources and introducing more effective economic incentives.

"These are concrete measures outlining what we can do," Harvey said.

Many of the technologies for achieving these results already exist, Drexhage and Harvey said, while other technologies are just around the corner, said Drexhage, including carbon sequestration — the burying of carbon dioxide beneath the earth to prevent it from entering the atmosphere.

The report also offers a unique look at the impact of the Kyoto protocol, the much-maligned international agreement that calls for participating nations to reduce greenhouse gas emissions to agreed-upon levels by 2012.

Kyoto has come under fire from a number of quarters, in part because heavy polluters such as the United States and China are not participating. Environmentalists have argued the greenhouse gas emission reductions of 5.2 per cent below levels produced in 1990 don't go far enough, while Canada's Conservative government has said they will not be able to meet the targets.

The IPCC report says while the impact of those targets "is projected to be limited," the real achievement of Kyoto is "the establishment of a global response to the climate program, stimulation of an array of national policies, the creation of an international carbon market and the establishment of new institutional mechanisms that may provide the foundation for future mitigation efforts."

Drexhage said even countries that aren't part of Kyoto have felt its impact.

"It's real accomplishment has been to galvanize national actions, even for those countries, like the United States and Australia, that aren't part of it," Drexhage said. "Whether you were going to be part of Kyoto or not, you had to have a national strategy."

Drexhage urged the establishment of an international regime to move beyond Kyoto and provide the incentives for clean energy and investment that will be necessary to make changes palatable to industries. He would like to see Canada establish such a plan.

"Here in Canada, we are consuming two to three times as much energy per capita as countries in Europe, and six to eight times more than developing countries, so we could be doing more," he said.

"The Canadian government needs to tell industry what targets it needs to reach and let industry figure out the economics," he said.

Canadian environmental consultant Erik Haites, who was a review editor for a section of the upcoming report, echoed the report's finding that the best policies tend to use unambiguous language, have goals that are both reachable and meaningful, and come with clear penalties for those who fail to comply.

"Agreements that set targets too low have had little effect on emission reductions, and volunteer agreements with no sanctions have traditionally not been enough," he told CBC News Online.

Scientists admit that the IPCC's most recent report is more political than the first two reports, but Haites, who has been contributing to IPCC assessment reports since 1995, said the report can only point a direction for policy makers, and that governments must take action to reach the targeted goals.

But he cautions that despite increased awareness of environmental issues around the world, the report might not have the impact hoped for by environmentalists.

"I'd be hard pressed to say if there was a specific action taken in response to the last report (in 2001), and I expect the same will be true for this report," he said.

"In Canada, different parties have different views on policy and this is unlikely to change," he said.

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