A Warm Pacific Ocean could release millions of tons of seafloor methane

Water off Washington’s coast is warming a third of a mile down, where seafloor methane shifts from a frozen solid to a gas. Researchers found that water off the coast of Washington is gradually warming at a depth of 500 meters, about a third of a mile down. That is the same depth where methane transforms from a solid to a gas. The research suggests that ocean warming could be triggering the release of a powerful greenhouse gas. Calculations suggest ocean warming is already releasing significant methane offshore of Alaska to Northern California. Methane hydrates are a very large and fragile reservoir of carbon that can be released if temperatures change. Methane is the main component of natural gas. At cold temperatures and high ocean pressure, it combines with water into a crystal called methane hydrate. Warming water causes the frozen edge of methane hydrate to move into deeper water. On land, as the air temperature warms on a frozen hillside, the snowline moves uphill. In a warming ocean, the boundary between frozen and gaseous methane would move deeper and farther offshore.  The recent sightings of methane bubbles rising to the sea surface are triggering the fate of any released methane.