London, August 19 (ANI): A team of scientists has said that they have evidence that the powerful greenhouse gas methane is escaping from the Arctic sea bed.
According to a report by BBC News, researchers said this could be evidence of a predicted positive feedback effect of climate change.
As temperatures rise, the sea bed grows warmer and frozen water crystals in the sediment break down, allowing methane trapped inside them to escape.
The research team found that more than 250 plumes of methane bubbles are rising from the sea bed off Norway.
The joint British and German research team detected the bubbles using a type of sonar normally used to search for shoals of fish.
Once detected, the bubbles were sampled and tested for methane at a range of depths.
The team said that the methane was rising from an area of sea bed off West Spitsbergen, from depths between 150 and 400m.
The gas is normally trapped as "methane hydrate" in sediment under the ocean floor.
"Methane hydrate" is an ice-like substance composed of water and methane which is stable under conditions of high pressure and low temperature.
As temperatures rise, the hydrate breaks down. So, this new evidence shows that methane is stable at water depths greater than 400m off Spitsbergen.
However data collected over 30 years shows it was then stable at water depths as shallow as 360m.
Temperature records show that this area of the ocean has warmed by 1 degree Celsius during the same period.
According to the research team, this is the first time that this loss of stability associated with temperature rise has been observed during the current geological period.
Professor Tim Minshull of the National Oceanography Centre at Southampton told BBC News, "We already knew there was some methane hydrate in the ocean off Spitsbergen and that's an area where climate change is happening rather faster than just about anywhere else in the world."
Methane gas rises from the sea bed in plumes of bubbles, with most of it dissolving before reaching the surface.
So far, scientists haven't detected methane breaking the ocean surface, but they don't rule out the possibility.
"There's been an idea for a long time that if the oceans warm, methane might be released from hydrate beneath the sea floor and generate a positive greenhouse effect," said Minshull. (ANI)