Arctic scientists discover new global warming threat as melting permafrost releases millions of tons of a gas 20 times more damaging than carbon dioxide.

    The first evidence that millions of tons of a greenhouse gas 20 times more potent than carbon dioxide is being released into the atmosphere from beneath the Arctic seabed has been discovered by scientists.

    The Independent has been passed details of preliminary findings suggesting that massive deposits of sub-sea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats.

    Underground stores of methane are important because scientists believe their sudden release has in the past been responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species. Scientists aboard a research ship that has sailed the entire length of Russia's northern coast have discovered intense concentrations of methane - sometimes at up to 100 times background levels - over several areas covering thousands of square miles of the Siberian continental shelf.

    In the past few days, the researchers have seen areas of sea foaming with gas bubbling up through "methane chimneys" rising from the sea floor. They believe that the sub-sea layer of permafrost, which has acted like a "lid" to prevent the gas from escaping, has melted away to allow methane to rise from underground deposits formed before the last ice age.

    They have warned that this is likely to be linked with the rapid warming that the region has experienced in recent years.

    Methane is about 20 times more powerful as a greenhouse gas than carbon dioxide and many scientists fear that its release could accelerate global warming in a giant positive feedback where more atmospheric methane causes higher temperatures, leading to further permafrost melting and the release of yet more methane.

    Four Canadian provinces are also included in the initiative, which aims to cut regional emissions by 15 percent below 2005 levels.

    Seven Western states and four Canadian provinces proposed a sweeping regional crackdown on global warming emissions Tuesday in the face of continuing reluctance by the Bush administration and Congress to pass comprehensive climate legislation.

    The Western Climate Initiative, endorsed by the 11 governors and provincial premiers, aims to slash regional greenhouse gas pollutants by about 15 percent below 2005 levels in the next 12 years.

    "We're sending a strong message to our federal governments that states and provinces are moving forward in the absence of federal action," said California Gov. Arnold Schwarzenegger, adding that the effort would spur renewable energy development and create "green jobs."

    California, which passed a landmark global warming law in 2006, is well on its way to curbing emissions. But other states and provinces will have to overcome opposition in legislatures and from influential businesses. And several states have yet to sign on, including Nevada, Idaho, Colorado and Wyoming. Nevada has the fastest-growing population in the nation, and Colorado and Wyoming are booming energy states.

    The plan also relies on a complex trading system in which businesses can buy and barter their way out of trimming emissions. Europe has instituted a carbon market, but not without some controversy. And many economists say that a tax on carbon would be a more efficient way to reduce global warming.

    When California made global headlines two years ago for a landmark law requiring a 25 percent cut in industrial greenhouse gases by 2020, some critics said the environmental advantages would be symbolic and net job losses significant.

    Now, two studies released this week by the California Air Resources Board, the state body charged with overseeing the project, claim to show that implementing the emission-cutting measures under the pioneering law would actually benefit California's economy and public health.

    The economic analysis says implementing the regulations will increase economic production by $27 billion, overall gross state product by $4 billion, overall personal income by $14 billion, and per capita income by $200.

    And the public health analysis concludes that programs under AB32 - also known as the California Global Warming Solutions Act of 2006 - will help eliminate 300 premature deaths statewide, avoid almost 9,000 incidents of asthma and lower respiratory symptoms, and avoid 53,000 workdays lost to illness.

    "The facts are in. These reports support the conclusion that guiding California toward a clean energy future with reduced dependence on fossil fuels will grow our economy, improve public health, protect the environment, and create a more secure future built on clean and sustainable technologies," said ARB chairman Mary Nichols on Wednesday.

    • Infrastructure investment must double, say experts.

    • Climate change likely to put four billion people at risk.

    Countries across the world will have to dramatically increase investment in dams, pipes and other water infrastructure to avoid widespread flooding, drought and disease even before climate change accelerates these problems, experts have warned.

    Investment needs to be at least doubled from the current level of $80 billion (£45.5 billion) a year, an international congress was told this week, and one leading authority said spending needed to rise to 1.5% of gross domestic product just "to be able to cope with the current climate" - one thousand times the current level.

    The warnings follow a summer of dramatic events, from hurricane flooding in the Caribbean and the east coast of America to desperate measures in drought-stricken Mediterranean countries, including importing water by ship.

    Rich nations suffer huge under-investment, but the threat of poor infrastructure to populations in developing countries is even greater, said Dr Olcay Unver, director of the United Nations' Global Water Assessment Unit.

    So serious is the problem that next year the UN's World Water Assessment Report will make one of its main messages the need for investment to "accelerate substantially", said Unver.

    "You can't justify the deaths of so many children because of lack of infrastructure or lost productive time of people [who are] intellectually or physically incapacitated because of simple lack of access to safe water or sanitation," he added.

    Grants Pass, Oregon - A group of forest scientists from the United States and Europe reports that a growing body of evidence settles an old question over whether old growth forests store more carbon dioxide from the atmosphere than they release.

    Based on a review of research from more than 500 forest sites around the world, the answer, published Thursday in an online edition of the journal Nature, is that most forests between 15 and 800 years old do, and the total amounts to about 1 billion metric tons a year, or about 10 percent of the net carbon uptake worldwide.

    Co-author Beverly Law, a professor of global change forest science at Oregon State University, said the findings argue for including credit for preserving old growth forests in the Kyoto Protocol and cap-and-trade schemes for controlling greenhouse gas emissions blamed for global warming.

    "If you have an old forest on the ground, it's probably better to leave it there than to cut it," she said. "For the countries that did sign on to Kyoto, it is suggesting that perhaps they need to consider unmanaged primary forests in their carbon accounting."

    The United States did not sign the Kyoto agreement.