How climate change is unlocking the ocean’s frozen methane

Luckily, the majority of the bubbling methane get lost while heading directly to the surface.

Scientists have detected a disproportionate number of methane bubble plumes off the Washington and Oregon coast. Further measurements, expeditions, drilling, and analyses are required to fully gauge the effects of climate change on the stability of methane in the world’s oceans.

The Environmental Defense Fund (EDF) warned that post-release, methane is 84 times more powerful than carbon dioxide, and that 25 percent of the man-made global warming experienced today is from methane emissions.

Methane bubbles are coming up from ocean vents off the Washington and Oregon coast, and a new study identified warming ocean temperatures one-third of a mile below the surface as likely responsible. The developed methane hydrate is unstable and sensitive to changes in temperature.

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. Moreover, findings revealed bubble plumes that rose at least 150 meters (490 feet) tall clearly originate from the seafloor.

Researchers explained that there are many marine microbes that feed on methane and convert it into carbon dioxide.

Another possible effect could be the destabilization of seafloor slopes where frozen methane acts as the glue that holds the steep sediment slopes in place.

Methane gas is slowly released at nearly all depths along the Washington and Oregon coastal margin.

It’s important to point out that the researchers have yet to confirm that the plumes are actually comprised of melting methane deposits.

Experts said that methane deposits are present in vast amount on the Pacific Northwest’s continental margin.

The research sought evidence of bubble plumes off the coast, such as based on research cruise observation, earlier studies, and reports from local fisherfolk.

A 2014 study from the UW documented that the ocean in the region is warming at a depth of 500 meters (0.3 miles), by water that formed decades ago in a global warming hotspot off Siberia and then traveled with ocean currents east across the Pacific Ocean. Methane gas in sea floor sediments forms a crystal lattice structure with water, called as methane hydrate, at cold-temperatures and high pressure.

Currently, methane hydrate appears to be decomposing and releasing a lot of gas; in fact, the margin where there are the greatest number of plumes is at the critical depth of 500 meters.

At present, co-author and oceanography associate professor Evan Solomon is analyzing the chemical composition of bubble plume samples emitted at about 500 meters deep off the Washington coast, seeing whether the gas comes from methane hydrates instead of other sources.