Subsurface Warming Could Cause Methane Gas to Bubble Off Washington Coast

A new study just released says that pockets of frozen methane deep in the ocean off the coast of Washington and Oregon are melting and releasing the toxic gas in to the atmosphere, according to a report in the Daily Mail.

What this might mean for climate change is uncertain, the researchers emphasized, though they said local marine life and fisheries will be affected.

The most infamous and abundant greenhouse gas is carbon dioxide. Indeed, one of the more alarming aspects of human-instigated climate change is the way it’s triggering the release of green house gases not related to human activity.

Researchers at the University of Washington looked at data on 168 bubble plumes observed in recent years, recorded by the sonar of fishing boats and scientific expeditions.

The study is set to appear in the journal Geochemistry, Geophysics, Geosystems.

The study, conducted by H. Paul Johnson, a professor of oceanography at the University of Washington, showed that methane hydrates began to escape the crust below the sea floor at a critical depth, indicating that there must be a certain threshold of temperature past which the methane is released. A new study said 168 bubble plumes had been detected in the past 10 years, a disproportionate number of which were found at a critical depth for methane hydrates’ stability.

Of these, about 14 were located at the “transition depth” in the ocean; there, there were more plumes per unit area than on surrounding parts of the Washington and Oregon seafloor. But the boom in their number may suggest that methane is now coming from dormant methane that was frozen for thousands of years.

Methane is suspected for previously causing big and often sudden swings in the Earth’s climate. The warming at this ocean level could melt methane deposits on the Cascadia subduction zone, which runs from northern California to Vancouver Island. As ocean waters warm, stored frozen methane in other regions of the world will likely be released in a similar manner.

“What we’re seeing is possible confirmation of what we predicted from the water temperatures: Methane hydrate appears to be decomposing and releasing a lot of gas”, Johnson said.

A previous study found that between the years of 1970 and 2013, more than four million metric tons of methane hydrate were released.

In addition, study co-author Evan Solomon and UW associate professor of oceanography, attests, “The results are consistent with the hypothesis that modern bottom-water warming is causing the limit of methane hydrate stability to move downslope, but it’s not proof that the hydrate is dissociating”.

Results show that methane gas is slowly released at nearly all depths along the Washington and Oregon coastal margin.

It’s also not clear how much methane gas is actually getting to the surface.

Solomon is now analyzing the chemical composition of samples from bubble plumes emitted by sediments along the Washington coast at about 500 meters deep.