As the world learns more and more about climate change and how to combat it, there remains a lesser known danger lurking below some people's feet.
Climate change is the result of greenhouse gases (GHGs), mainly carbon dioxide (CO2) and methane (CH4), building up in the atmosphere. These gases absorb and trap heat from the sun, causing the Earth and its atmosphere to warm. They can be produced naturally (methane from wetlands) or can be man-made (carbon dioxide from burning fossil fuels).
Greenhouse gases are beneficial in the appropriate atmospheric concentrations, but human activities since the beginning of the industrial revolution have led to too much of a good thing. The planet is now warming at an accelerated rate and we face serious social, economic, and environmental consequences as a result.
Carbon dioxide is considered by many to be the most important greenhouse gas. Climate scientists more often refer to atmospheric CO2 concentrations than any other greenhouse gas and emission measurements are frequently given in CO2 equivalents.
But don't count methane out. Not only is it 20-25 times more effective at trapping heat than carbon dioxide, but there are vast amounts of it around the world just waiting to be released. They are stored in what are known as methane hydrates.
Methane hydrates (also known as "natural gas hydrates" or "methane clathrates"), are frozen deposits of methane found mostly in marine sediments along continental margins (see image below) and in permanently frozen soil (permafrost) at the higher latitudes in the northern hemisphere.
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| There is a lot of methane stuck in ice out there. |
Rather than reacting or bonding with the water, the methane is encased in the ice. Once warmed to the appropriate temperature, and depending on the pressure being applied, it is released. This paper suggests that most of the methane being released from the seafloor never makes it to the atmosphere, but rather gets dissolved in the ocean and converted to CO2, which then impacts ocean acidity.
Worldwide reserves of methane hydrates are estimated at 6 to 29 times the worldwide proven conventional natural gas reserves (conventional natural gas is what we currently drill for and use). These numbers have huge economic implications. If nations and/or companies can develop the technology to exploit these resources in an economically viable way, they stand to profit handsomely from these reserves.
But there are also huge environmental implications. The release of the methane in these hydrates, whether it is abrupt or gradual, is a concern to climate scientists - and it should be to us all.
It has been suggested that an abrupt release of this methane from 1) the rapid warming of deep sea waters, 2) the sudden mass movement of sediment in the oceans near our shores, or 3) a combination of the two, could send the Earth's climate spiraling out of control. However, this theory is not well supported and it is very unlikely in the near future.
The more accepted scenario is a more gradual and chronic release of the methane, exacerbating global warming, but not resulting in anything catastrophic in nature.
This will, at least in part, be accomplished by the expansion of wetlands at higher latitudes in the northern hemisphere. This frozen area of the Earth could be converted more and more to these methane-producing hotbeds as permafrost thaws, soil rich in organic matter is exposed, and precipitation increases. Wetlands, mainly of the tropical variety, are currently the largest natural source of methane emissions. Microorganisms that thrive in those low-oxygen environments decompose biomass and produce methane on a large scale.
I hope it goes without saying, but we should probably be careful and fully understand methane hydrates before attempting to exploit them.
Well, that's it for now. I hope you enjoyed learning about methane hydrates. Check back soon for another post on some random environmental science topic!
If you want to learn more, here is a good BBC article on methane leakage from deposits off the United States coast.