Ice that burns?

Photo: The Canadian Press

Gas flares from a drilling platform that extracted natural gas from combustible ice trapped under the South China Sea.

Commercial development of the globe's huge reserves of a frozen fossil fuel known as "combustible ice" has moved closer to reality after Japan and China successfully extracted the material from the seafloor off their coastlines.

But experts said Friday that large-scale production remains many years away — and if not done properly could flood the atmosphere with climate-changing greenhouse gases.

Combustible ice is a frozen mixture of water and concentrated natural gas. Technically known as methane hydrate, it can be lit on fire in its frozen state and is believed to comprise one of the world's most abundant fossil fuels.

The official Chinese news agency Xinhua reported that the fuel was successfully mined by a drilling rig operating in the South China Sea on Thursday. Chinese Minister of Land and Resources Jiang Daming declared the event a breakthrough moment heralding a potential "global energy revolution."

A drilling crew in Japan reported a similar successful operation two weeks earlier, on May 4 offshore the Shima Peninsula.

For Japan, methane hydrate offers the chance to reduce its heavy reliance of imported fuels if it can tap into reserves off its coastline. In China, it could serve as a cleaner substitute for coal-burning power plants and steel factories that have polluted much of the country with lung-damaging smog.

Estimates of worldwide reserves range from 280 trillion cubic meters (10,000 trillion cubic feet) up to 2,800 trillion cubic meters (100,000 trillion cubic feet), according to the U.S. Energy Information Administration. By comparison, total worldwide production of natural gas was 3.5 billion cubic meters (124 billion cubic feet) in 2015, the most recent year available.