Whoa, that's quite a claim. But scientists and environmentalists have known it for a while, at least since 2005 when those deposits were confirmed. But it seems to have escaped public attention. Especially when it comes to the debate that pits renewable and green sources against fossil fuels, such as petroleum, coal and natural gas.
The Global Warming Policy Foundation summarized a story in the Sunday Times (subscription required) thusly:
Race begins for wonder gas ‘frozen under sea’A discovery by scientists may have more than doubled the world’s energy reserves. They have found vast amounts of natural gas frozen into the sea bed, potentially containing more energy than all the world’s known coal, oil and gas reserves combined. The research follows the growing excitement generated by Japan Oil, Gas and Metals National Corporation (Jogmec), which has been drilling test wells into methane hydrate reserves in the Nankai trough, off Japan’s southwest coast. It predicts the first gas will be extracted this year, and suggests there could be enough methane hydrate in the trough to supply all Japan’s energy for 300 years. --Jonathan Leake, The Sunday Times, 15 January 2012
The U.S. Geological Survey has issued a fact sheet, "Gas (methane) hydrates--a new frontier," which is available here.
The implications are staggering if a commercially viable and safe way can be found to extract, process and transport the fuel.