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Author Topic: Anoxic seas as a carbon sink  (Read 1670 times)


  • New ice
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Anoxic seas as a carbon sink
« on: April 04, 2016, 06:08:56 PM »
I was just reading this link from the British Geological Survey, which explains how the Earth came out of a high CO2 state in the past.

Namely by large quantities of organic carbon not being decomposed in anoxic waters and instead settling on the seabed and forming a layer of black shale, locking away the carbon. Apparently this happening on a global scale over thousands of years lead to CO2 concentrations falling and a period of global cooling.

I had so far considered anoxic oceans as just another devastating consequence of global warming, but could we use it to our advantage as a macroscopic carbon sequestration method?

We know of efforts to investigate the possibilities of using seeded phytoplankton blooms to lock away carbon, but I thought it turned out not to be very effective at removing carbon from the cycle. However, if we can seed blooms in areas where the water is already or is close to being anoxic, then perhaps the carbon from the seeded bloom could be removed from the cycle. We could keep seeding huge blooms over huge areas of anoxic waters, and lock away lots of carbon. Using a relatively simple method and natural processes to lock away much more carbon than any of these carbon sucking technologies would be able to achieve for the investment and effort.

Not saying it'll solve all our problems (we'll still need to get off fossil fuels ASAP), but as a means to restoring the global energy imbalance, it might be one of the better options available to us for locking away carbon cheaply on a huge scale?

Another arrow in our CCS quiver at the least.

Anyone seen anything recent about this idea or have any input?

I just looked at the wikipedia link for this, and it seems promising, perhaps even not requiring the anoxic waters.


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Re: Anoxic seas as a carbon sink
« Reply #1 on: April 04, 2016, 11:08:46 PM »
A Canfield ocean is not a godd thing.


  • New ice
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Re: Anoxic seas as a carbon sink
« Reply #2 on: April 04, 2016, 11:49:24 PM »
The Black Sea already meets the conditions of the OP.

Relatively fresh water from river discharge overlies salty, anoxic, H2S-rich, very toxic deeper waters. The deep anoxic water is held in by the shallow Bosporus Strait, and the whole column is highly stratified by temperature and salinity.

I'm sure the surface waters are already being enriched by fertilizer runoff. Maybe this is an already operating unintentional carbon sink of some significant size.

I would hate to destabilize it by further meddling. It wouldn't take much H2S to ruin the day for all life downwind of a Black Sea Canfield burp.


  • Nilas ice
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Re: Anoxic seas as a carbon sink
« Reply #3 on: May 30, 2019, 02:54:16 AM »
Global warming could enlarge world’s largest dead zone