Earthquakes may contribute to global warming by releasing greenhouse gas from the ocean floor, a study suggests.
Scientists uncovered evidence that a large earthquake in 1945 released more than seven million cubic metres of methane into the North Arabian Sea.
The discovery exposes a natural source of greenhouse gas emissions that has not been considered before, they claim.
As a greenhouse gas, methane is 20 times more potent than carbon dioxide, but less abundant in the atmosphere.
Enormous quantities of methane are locked in icy structures called hydrates on the floors of the continental shelves surrounding the Earth's land masses.
An estimated 1000 to 5000 gigatonnes of carbon is trapped in methane hydrates – more than the total amount released by burning fossil fuels each year.
Analysis of sediment cores taken from the North Arabian Sea in 2007 revealed chemical signs of large-scale methane release.
A search of historical records showed that a magnitude 8.1 earthquake had occurred nearby in 1945.
"Based on several indicators, we postulated that the earthquake led to a fracturing of the sediments, releasing the gas that had been trapped below," said lead scientist Dr David Fischer, from the University of Bremen in Germany.
A conservative estimate indicated that roughly 7.4 million cubic metres of methane had escaped, said the researchers writing in the journal Nature Geoscience.
"There are probably even more sites in the area that had been affected by the earthquake," Dr Fischer added.
Methane hydrates have been suggested as an energy source, but mining them is expensive and risky.
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article