Scientists have discovered that water off the coast of Washington is warming at a depth where solid methane can transform into gas, indicating that the warming of the ocean is triggering the release of the heat-trapping greenhouse gas.
Methane, which is several times more potent than carbon dioxide in fueling global warming, forms into methane hydrate wherein it gets enclosed in frozen water given the right conditions: cold temperature and high ocean pressure.
With the warming of the temperature, however, methane hydrates that serve as a large reservoir of the greenhouse gas release methane, and deeper water off the Washington coast is warming the most over the past four decades and which researchers attribute to climate change.
Scientists have long known that climate change will release methane from gas hydrates, with researchers primarily focusing on the deposits in the Arctic.
A new study published in the Geophysical Research Letters on Dec. 5 found that between 1970 and 2013, about 4 million metric tons of methane had broken out from hydrate decomposition off the coast of Washington.
Researchers said that this is a significant amount in that it is 500 times the rate that methane is naturally released from the bottom of the sea. It is also equivalent to having the amount of methane that was released in the 2010 Deepwater Horizon disaster.
"We calculate that methane equivalent in volume to the Deepwater Horizon oil spill is released every year off the Washington coast," said study researcher Evan Solomon from the University of Washington.
Solomon and colleagues said that they are shocked by the results because these kinds of methane releases are often expected to happen in the Arctic.
"Sediment column thermal models based on observed water column warming trends offshore Washington (USA) show that a substantial volume of gas hydrate along the entire Cascadia upper continental slope is vulnerable to modern climate change," the researchers wrote. "Dissociation along the Washington sector of the Cascadia margin alone has the potential to release 45-80 Tg of methane by 2100."
The researchers said that they still do not know where the released methane gas will end as most of it could be consumed by methane-absorbing bacteria in the seafloor, which could prevent the release of large amounts of methane into the atmosphere.
The downside to this, however, is that seawater could become more acidic and oxygen deprived. Some methane may also be released into the atmosphere, where it could contribute to the warming of the planet.
