Discovery Of The Source Of World's Largest Methane Pool Is Anything But Good News

The methane cache stretches from the lava-filled coast of the Hawaiian archipelago to Central America. Allen.g/Shutterstock

Methane, for the most part, isn’t a gas we’d like to find more of on Earth. Although it decays a lot faster in the atmosphere than carbon dioxide, it warms the planet 28-36 times more effectively per unit in the long-term, which makes it a powerful catalyst for global warming.

A new study by researchers from Queen Mary College London (QMUL) has recently been conducting research on a record-breaking cache of it within the Pacific Ocean. As they note in the journal International Society for Microbial Ecology, this is the largest marine methane deposit in the world.

This enormous "pool" of methane is one that can be found stretching all the way from the western coast of Guatemala to the shores of Hawaii, a distance of around 8,000 kilometers (almost 5,000 miles). Collecting sediment from the seafloor, the team of QMUL geoscientists confirmed for the first time that this source of methane is predmonantly biological: small microbes are feeding this gigantic ocean of flammable, currently frigid gas.

Methane comes from a variety of sources. Cattle produces a heck of a lot of it, as do termites. A lot of the world’s methane, though, comes from natural sources – trapped within the permafrost regions of Siberia and North America, and, in this case, locked up in the sediments of the deep ocean, or along shallower continental shelves.

These caches are normally created when certain microbes break down organic matter under low oxygen conditions, but there are some geological processes that produce it too. Over time, their methane expulsions build up and often get frozen into place as solid compounds named “methane hydrates.” When the overlying water or ice gets warmer or more acidic, these stores become unstable and begin leaking.

Craters off the coast of Norway reveal that when this methane becomes particularly unstable, it explodes, or at the very least, it's released rather rapidly. These don't just leave huge scars at the bottom of the sea; they also transform a lot of that methane into carbon dioxide, the primary antagonist driving climate change.

It's not yet clear how much methane makes it into the atmosphere, but it remains a concern about climatologists seeking to sort out this uncertainty. One recent review suggests that it's unlikely to escape skywards in any significant quantities - but the processes here remain fairly unclear at present, and the possible threat of a sudden, significant methane release can't be ignored.

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The zone marked 'ETNP roughly marks the position of the methane cache.

Case in point: around 56 million years ago Earth went through a rapid warm period, heating up by 5 to 8°C (9 to 15°F) in just 20,000 years. The so-called Paleocene-Eocene Thermal Maximum (PETM) triggered several significant extinction events, and part of the blame has occasionaly been placed on huge stores of methane hydrates going up in smoke, so to speak.

The PETM’s unusually high rate of warming equates to 0.025°C per 100 years. The current pace of man-made global warming suggests that our own efforts to boil the planet are proving to be far more effective, but any sudden methane release from the hydrosphere or cryosphere would potentially give it a real shot in the arm – and the warmer the world gets, the more likely this is to happen.

So although we don't know how likely it is to enter out atmosphere over time, this colossal cache of methane is a no good, very bad, terrible thing, no matter where it's coming from. If there are any supervillains out there, we’d suggest going to find it and setting it all alight – if you’d like to watch the world burn, anyway.

Update: This article originally referred to the discovery as relating to the methane "pool" itself; in fact, it's the source of the methane pool that's the discovery here. 

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