Microorganisms in Seabeds Release More Methane as Oceans Get Warmer, Study Shows

Large quantities of methane could be released from the microorganisms that live beneath the seafloor as a result of warming oceans, which could amplify global warming.

A new study creates a method to comprehend how microorganisms contribute to rising methane emissions from seabeds.

Methane Hydrate

Methane, a powerful greenhouse gas, is stored beneath the oceans in vast reservoirs with water in a solid ice-like mixture. The name of this substance is methane hydrate. Various worries about the possibility that warming the seafloor could hasten this methane's release and possibly even send it into the atmosphere, where it would contribute to further global warming, have been voiced for more than three decades. Fortunately, most of this methane hydrate is buried hundreds of meters under the ocean's surface. Even if warming causes this methane hydrate to melt and release methane gas, it was anticipated that the natural microbial filters on the seafloor would destroy almost all of the methane before it ever entered the open ocean.

There have been some gaps in their understanding of the pertinent seafloor processes, though. In particular, is seafloor warming likely to occur quickly enough for methane hydrate to melt quickly enough to overwhelm natural microbial filters and eventually bypass them?

Delicate Filter

Christian Stranne, an assistant professor at the Department of Geological Sciences, Stockholm University, said that the Sulfate-methane transition, the sediment's microbial filter layer where methane is removed, is a delicate structure. He goes on to say that it takes a long time for the filter layer to develop and reach its maximum capacity for consuming methane. Microorganisms that intake methane in anaerobic environments make up the living filter. Based on the speed at which methane is nearing the filter, the filter also moves vertically within the sediment.

Read also: Methane Emitting from Arctic Seabed for Millions of Years 

Increased Release of Methane

Stranne and his associates from Linnaeus University and Stockholm University have combined a new model of the biological behavior as well as vertical movements of this microbial filter with existing models of the physical behavior of seafloor sediments in a recent study, which was just published in Communications Earth and Environment. The model's physical components depict processes like crack formation and methane's ability to move through silt after the methane hydrates melt.

Stranne explains that suddenly more methane is rising through the sediment, as might occur if the methane hydrate starts to melt more quickly. The filter may need decades to adjust to start consuming methane at the new speed. Their most recent research demonstrates that significant amounts of methane can seep past the filter and into the ocean water when it is not restored.

Even after this window of opportunity, additional methane-destructive processes must take place before melting hydrates' methane enters the seawater. Due to these procedures, it is almost impossible for significant amounts of methane produced during the melting of methane hydrates to enter the atmosphere.

Melting Methane Hydrates

Stranne notes that other areas, such as the Arctic continental shelves, where methane released from the seafloor is much shallower and more likely to reach the atmosphere, can use the techniques illustrated in this study.

Methane hydrates, he continued, are a significant source of carbon storage, so it is crucial to comprehend how they engage with alterations in the ocean and possibly the atmosphere over both long and relatively short timescales. Because of their research, scientists now understand that melting methane hydrates is a real possibility for temporarily getting around what was once believed to be a robust filter in the sediment.

However, the rate of warming is very significant. Stranne emphasized that their findings imply that the filter can continue to function at a high level even if ocean warming is significantly slower than 1 °C every 100 years. Unfortunately, some of the oceans are predicted to warm faster than 1 °C, Science Daly reports.

Related article: Melting Permafrost Leaves 90ft Deep Craters Beneath the Arctic Seafloor