By Alister Doyle, Environment Correspondent

OSLO, March 5 (Reuters) - Tackling climate change and other environmental hazards is affordable but urgent action is needed to avert irreversible damage, the Organisation for Economic Cooperation and Development (OECD) said on Wednesday.

The 30-nation OECD said possible environmental safeguards might slow world growth by just 0.03 percent a year -- meaning that by 2030 the global economy would be 97 percent bigger than in 2005 instead of almost 99 percent larger with no measures.

"This is not a lot to pay," said Angel Gurria, head of the Paris-based OECD group of rich democracies in a 520-page Environmental Outlook issued in Oslo, saying costs were similar to those of an insurance policy.

"The consequences and costs of inaction...would be much higher," he said.

The study identified issues for most urgent action including global warming, losses of species of animals and plants, water scarcity, illegal logging, pollution and hazardous chemicals.

"If no new policy actions are taken, within the next few decades we risk irreversibly altering the environmental basis for sustained economic prosperity," it said.

The report recommended overhauling sectors that cause most damage -- energy, transport, agriculture and fisheries. "Removal of environmentally harmful subsidies, particularly for fossil fuels and agricultural production, is a necessary first step," Gurria said.

POLLUTION

A hypothetical policy package included a 50 percent cut in farm subsidies, a $25 per tonne tax on emissions of heat-trapping carbon dioxide phased in by region, new biofuels, measures to cut air pollution and improved sewerage systems.

The measures would limit overall growth in greenhouse gas emissions to 13 percent rather than 37 percent by 2030. Stiffer greenhouse gas goals would be a slightly bigger brake on economic growth.

The study adds to evidence that curbing global warming, blamed mainly on use of fossil fuels, is affordable. Last year, the U.N. Climate Panel also said that measures to curb climate change would cost between 0.06 and 0.1 percent of world gross domestic product a year to 2030.

And a 2006 report by former World Bank chief economist Nicholas Stern warned that unchecked warming would be as damaging as world wars or the Great Depression with more floods, droughts, heatwaves and rising seas.

More than 190 governments agreed in Bali, Indonesia, in December to work out by the end of 2009 a new treaty to fight climate change and succeed the Kyoto Protocol, which binds 37 developed nations to cut emissions by 2012.

The United States is outside Kyoto, with President George W. Bush reckoning it would damage the U.S. economy and saying it wrongly omitted 2012 curbs for developing nations. Washington has agreed to join a new global plan.

To combat climate change, the OECD said "developed countries will need to work closely with emerging economies -- especially Brazil, Russia, India, Indonesia, China and South Africa."

Without curbs, greenhouse gas emissions from China, India, Russia and Brazil alone "will grow by 46 percent to 2030, surpassing those of the 30 OECD countries combined," it said.

The OECD said that its members can point to some successes in recent decades -- industrial pollution has fallen, the area of forests and natural protected areas has increased and economies have become more efficient. -- For Reuters latest environment blogs click on: http://blogs.reuters.com/environment/ (Editing by Ibon Villelabeitia)

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