Methane Will Wreak Havoc in Changing Climate

A two-part study investigating the impact of methane – one of the most potent of greenhouse gases – has found that millions of tonnes of methane currently frozen in sediment beneath the Arctic Ocean will wreak havoc if released into the oceans.

This, despite beliefs that the ocean is always able to handle any amount of methane release.

The project found that buried deposits of clathrates – icy crystalline compounds that encase methane molecules – will break apart as the global temperature increases over the next few decades. Once that happens, the methane will then seep into the surrounding ocean, in this case, the Arctic Ocean, and eventually overwhelm the natural balance.

This image, from a simulation in which oxygen levels were limited, reveals methane concentration in the Arctic Ocean after 30 years of clathrate dissociation due to ocean warming. The colors indicate depth-integrated methane concentration in millimoles per square meter. The marine environment is no longer able to break down some of the methane, as indicated by spikes in methane concentration at all eight plumes, most notably at the plumes in the Okhotsk Sea and Bering Sea at the bottom of the image. Further research will explore how much of this methane will reach the surface. North America is on the right, Russia is on the left.

As a result, after only three decades of methane seepage, supplies of oxygen, nutrients and trace metals required by the microbes that normally disintegrate the methane will dwindle, and thus the oceans ability to deal with the levels of methane. The oxygen level of the ocean will drop, localized acidification will set in, and the ecosystem will suffer as the environment is no longer able to support life as it once used to.

In the end, the methane will reach the surface of the ocean, and seep into the atmosphere, affecting the climate change and possibly speeding it.

“The amount of methane entering the ocean is huge and it changes the water chemistry dramatically,” says Matthew Reagan of Berkeley Lab’s Earth Sciences Division.. “It consumes oxygen, the microbes stop eating, and methane can reach the surface.”

This image reveals simulated dissolved oxygen concentration, in micromoles, at a depth of 300 meters after 30 years of clathrate dissociation. Regions of severe oxygen depletion are indicated by white and purple shades.

“Our simulation found that large methane releases erode the ocean’s ability to consume methane. At this scale, resource limitations come into play,” said Reagan.

“Large-scale methane releases have a greater impact than we anticipated,” adds Reagan. “When this happens, microbes cannot consume all of the methane because there isn’t enough oxygen to fuel them.”

Source: Lawrence Berkeley National Laboratory (Berkeley Lab)

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