Detonating the methane time bomb

Tundra at Bering Land Bridge National Preserve
Vast quantities of methane are trapped in the tundra | Photo by Bering Land Bridge National Preserve via Flickr. CC BY 2.0

As world leaders prepare for next year’s UN climate conference, unprecedented numbers of people around the world are calling for urgent action to address change.

The activist group Avaaz issued one of the most popular rallying points – a petition demanding leaders commit to clean energy, currently with 2.2 million signatures. In the petition, Avaaz director Ricken Patel rouses the public to action by stating that “one top scientist just warned that we are all “f*cked” if global warming releases gigantic amounts of methane gas from the arctic tundra”.

The scientist mentioned is Dr Jason Box, who has been studying the melting of the Greenland ice sheet for almost two decades. It was after discovering huge quantities of methane are escaping the sea floor that he went on record as saying that even “Even if a small fraction of the Arctic carbon were released to the atmosphere, we’re f*****d”. Dr Box has since been lauded as a respected climatologist with an ability to convey the urgency of the climate issue with refreshing vigour.

However, Dr Box is not the first to draw the attention to the potentially disastrous impacts of methane being released into the atmosphere as part of climate change. Dr Natalia Shakhova and colleagues at the University of Alaska at Fairbanks have for several years charted the release of methane along the East Siberian Ice Shelf.

Structure of a gas hydrate
Structure of a gas hydrate (methane calthrate) | Image by Wusel007 via Wikimedia, CC SA 3.0

Many scientists agree that huge quantities of methane are trapped in ocean sediments, at the bottom of lakes and in the frozen permafrost around arctic regions. The methane is held in ice-like structures called ‘calthrates’, or gas hydrates. According to Dr Beau Webber, a physicist who has been researching the properties of methane calthrates, the structure is “a molecule of gas with a cage of water molecules around it”.

Calthrates are stable at around 0°C and at high pressure, but slight temperature increases cause them to break down, releasing methane into the air. As global temperature increases cause sea ice to shrink and permafrost to thaw, vast reserves of trapped methane could escape. Worryingly, research conducted by a team from the University of Oxford indicates that a small increase in temperatures (an increase which is almost inevitable) could result in widespread melting of Siberian permafrost.

Methane is a powerful greenhouse gas with a warming effect on the Earth over 20 times greater than carbon dioxide. Scientists such as Dr Box and Dr Webber agree that in this scenario, the resulting temperature increases could cause further methane releases in a self-reinforcing cycle. Some predict dramatic global warming over a few short years, leading to unprecedented environmental devastation with huge costs.

Some scientists question the plausibility of an “arctic armageddon”  in a debate charted by Dr Nafeez Ahmed in The Guardian.

However, there is good reason to treat seriously the risk of methane escaping from the planet’s surface into the air. Methane cannot be removed from the atmosphere by lowering global temperatures. As Dr Webber makes clear, “that will take another ice age, and we will be left with the greenhouse gas in the atmosphere”.

Clearly this is not just hot air, but an issue which should spur us all to take action.