Methane Emissions from Hokkaido Offshore Seabed Identified

On April 18, 2005, a joint research group involving the Japan Agency for Marine-Earth Science and Technology, the National Institute for Environmental Studies and Ibaraki University announced results of their research showing that methane emissions due to destabilization of submarine methane hydrate layers most likely occurred between the last glacial period (23,000 years ago) and the last warming period (17,000 years ago), when ice sheets receded. The group also disclosed that a lot of evidence of this phenomenon was discovered in analyzing marine sediments off the coast of Tokachi in Hokkaido, Japan's northernmost island.

Methane hydrate is a sherbet-like solid composed of methane and water molecules. It is expected to work as a next-generation energy source and a great deal of it is found off the coast of Tokachi.

This discovery is the world's first indication that the northwest Pacific was an area where frequent methane emissions from methane hydrate layers occurred during the last glacial period. Methane hydrate layers embedded in the sea bottom may have melted and emitted large volumes of methane, which is likely to have been closely related with former episodes of rapid global warming.

A decrease in pressure is cited as a possible cause of methane hydrate layer destabilization, as the sea level at that time was 100 meters lower than it is today. Another possibility now under discussion is large-scale tectonic plate boundary earthquakes in this area. Further research will be needed to explore possible causal relationships.



Posted: 2005/07/31 05:13:37 PM
Japanese version