May 4 (Bloomberg) -- Greenhouse gases in the atmosphere can be kept at levels that avoid the worst ravages of global warming by using available technologies and strategies, a United Nations panel said.

Keeping concentrations of gases at levels similar to those in the air today will cost less than 3 percent of world economic output by 2030, the UN Intergovernmental Panel on Climate Change said today in its third report of the year.

``We can go a long way to addressing this problem at relatively low costs with a range of options across a lot of sectors,'' Pete Smith, professor of global change at Aberdeen University in Scotland and a lead author of the study, said in an interview in Bangkok. ``We've got a big problem on our hands and this report provides governments with a way out.''

In two earlier reports this year, the panel, or IPCC, has said global warming is very likely caused by human activities including the release of gases from burning fossil fuels, and that rising temperatures will cause increased floods, droughts and extinctions of species. The panel's work is designed to feed into government policy on tackling climate change.

Today's document, debated line-by-line by government envoys from more than 120 nations meeting in Bangkok, was handed to reporters before a press conference today.

`Step Forward'

Rajendra Pachauri, chairman of the IPCC, told reporters in Bangkok the study is a ``remarkable step forward'' from the panel's last review of climate change, in 2001.

The report says that stabilization of greenhouse gases can be achieved by changing the energy mix used around the world, introducing more fuel-efficient vehicles and appliances, improving home insulation and changing the way agricultural land is managed. Individuals can also change their lifestyles.

``An extremely powerful message in this report is the need for human society as a whole to start looking at changes in lifestyles and consumption patterns,'' Pachauri said, adding that people could take simple measures such as turning down the central heating and putting on a cardigan.

``This report highlights the importance of deploying a portfolio of clean energy technologies, consistent with our approach,'' Harlan Watson, head of the U.S. delegation, said in a statement.

Carbon Trading

Another tool available to government is carbon trading, according to the report. Establishing a price equal to $50 per ton of carbon dioxide could reduce emissions by more than half and a price of $100 could achieve a 63 percent cut, because of the incentives to develop cleaner energy sources, it said.

Under carbon trading, companies are set emission targets. If they undershoot those targets they're able to sell credits to other businesses that are unable to meet their targets.

Emissions of carbon dioxide, the most important greenhouse gas, are projected to rise by as much as 110 percent by 2030 if no action is taken to minimize them, the panel said. Scientists have linked the gas, produced by burning fossil fuels, to climate change. Higher emissions lead to higher temperatures, they say.

``If we continue to do what we are doing, then we are in deep trouble,'' said Ogunlade Davidson, co-chair of the working group that produced the report.

Atmospheric concentrations of greenhouse gases are about 425 parts per million (ppm) and rising. Stabilizing greenhouse gases at 445 ppm may hold increases in global temperature since industrialization at 2 degrees Celsius, according to the report. That's the level beyond which the European Union has said the effects may become dangerous and irreversible. Global average temperatures have risen 0.76 of a degree already.

Emissions Peak

To achieve stabilization at that level, emissions must peak by 2015 and then decline by 50 percent to 85 percent by 2050, the panel said, adding that it will shave under 0.12 of a percentage point of world growth a year, leading to a cumulative cost of less than 3 percent of output by 2030.

The cost is a bargain compared with the cost of inaction, said Hans Verolme, head of the World Wildlife Fund's climate change campaign. A U.K. government report last year said that failure to take action to stave off climate change would cost the world 5 percent to 20 percent of GDP.

``We can keep the climate safe and we can do that with currently available technologies at a cost that is almost negligible,'' Verolme said in an interview in Bangkok. ``We don't need to wait for a silver bullet.''

Kyoto Protocol

The cost of stabilizing atmospheric greenhouse gases at between 535 and 590 ppm would be about 0.6 percent of world output, and at 590 to 710 ppm, the cost would be 0.2 percent, according to the panel. Those concentrations equate to temperature gains of as much as 3.2 and 4.0 degrees Celsius.

At present, 35 countries and the European Union are bound by the Kyoto Protocol, which requires them to cut emissions of greenhouse gases by a combined 5 percent by 2012, when its provisions end. The U.S. rejected the treaty in 2001, and developing nations such as China aren't assigned targets.

Today's report can now be used by governments when they meet in Bali, Indonesia, in December to discuss climate change and a potential successor to the Kyoto Protocol.

``The science that the IPCC has been able to assess will have a direct impact, and we hope a profound influence'' on the talks, Pachauri said. ``It's probably naive to believe that merely to develop the technologies in laboratories and workshops will be the answer, unless there is a package of policies and unless there are market forces.''

To contact the reporter on this story: Alex Morales in Bangkok at amorales2@bloomberg.net

Last Updated: May 4, 2007 06:40 EDT