The methane bubbles act as a potent greenhouse gas, too, if they emerge all the way up and reach the surface, although the study said they seem to be consumed on the way up, with marine microbes converting the gas into carbon dioxide and producing conditions that are lower-oxygen and more acidic in the deeper offshore water. That’s close to the amount released by the 2010 Deepwater Horizon blowout in the Gulf of Mexico.
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Methane has largely contributed to sudden swings in Earth’s climate in the past. Researchers have reported a large number of bubble plumes emitting at a critical depth of ocean, which they think might be the plumes of frozen methane.
“We see an unusually high number of bubble plumes at the depth where methane hydrate would decompose if seawater has warmed”, said Professor Johnson.
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.
Due to rising sea temperatures below surface, more methane bubbles up off Oregon and Washington coasts.
Fourteen bubble plumes emerged out in the coasts of Oregon and Washington and were monitored within the transition depths. Plus, if methane continues to be released from frozen deposits, seafloor slopes may become destabilized since there is no frozen methane to keep them glued to one another. Much of the methane on Earth is actually trapped, frozen in the ocean, but as oceans warm up, this powerful greenhouse gas could be released.
Methane deposits are abundant on the continental margin of the Pacific Northwest coast. A 2014 study showed 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.
Yet the methane hydrate itself is highly unstable and even slight temperature changes can cause it to break apart.
“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”, study co-author Evan Solomon opined, reports Gizomodo, which added that researchers have not yet confirmed that melting methane deposits are causing the plumes. 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.
Now, scientists are collecting chemical samples emitted by sediments along the coasts to narrow in on what could be causing the plumes, and how the plumes may ultimately impact local waterways.
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Results will confirm whether the gas originates from methane hydrates rather than from a few other source.
