Methane is bubbling up from unexpected places on the ocean floor, raising concerns on its implications for global warming.

Researchers have detected more than 500 methane vents on the Atlantic Ocean floor off the US east coast, reports NBS News.

The gas could contribute to global warming, say scientists, pointing out that some of the detected emissions originate from depths where the warming may have in fact led to the leaks.

In the past, methane seeps have been largely detected along the continental shelf or above regions of tectonic activity.

The discovery of the seeps along the continental margin this time suggests that scientists will have to start looking for their presence in many other places across the ocean floors, and factor this into their climate models.

While the gas detected has not yet been sampled, the scientists have arrived at their conclusions based on circumstantial evidence following the depth and temperatures of their origin.

About 440 of them originate at depths which are at the limit of stability and may be getting affected by the warming of waters.

The gas is said to be leaking from gas hydrates which are ice-like condensates of methane and water formed under the cold temperatures and high pressures of the ocean floor.

While come of the carbon in the hydrates gets naturally oxidised and ends up acidifying the ocean, some of it ends up as rock carbonates after centuries, and some of it escapes to the surface as methane or carbon dioxide.

This last segment could be increasing with the rising temperatures of the waters.

Impact on climate

Hydrates hold as much as 10 times more carbon than the atmosphere. John Kessler, a chemical oceanographer at the University of Rochester in New York, noted in an article accompanying the new study that direct transfer of even a small fraction of this methane to the atmosphere can have catastrophic effects on Earth's climate.

However, not all that is released reaches the surface. "The methane is dissolving into the ocean at depths of hundreds of metres and being oxidised to CO2," Prof Adam Skarke from the Mississippi State University, who led the study, told BBC.

Prof Skarke and his colleagues estimate that worldwide there may be around 30,000 of the type of seeps they have discovered.

Ocean acidification has led to extinctions of marine life in the past. One such event is believed to be the catastrophic extinction that took place 252 million years ago at the Permian-Triassic boundary.