Carbon sequestration - artificial vs natural.

Carbon sequestration is a term you will increasingly hear over the coming years. This article provides a basic explanation of what it is, some of the suggestions of how humans may go about artificial sequestration and some of the unknown and dangers involved.

Natural carbon sequestration 

Natural carbon sequestration is a cycle that's been happening on this planet for billions of years. It's simply the process by which nature has achieved a balance of carbon dioxide in our atmosphere suitable for sustaining life. Animals expel carbon dioxide, as do plants during the night; forest fires belch carbon dioxide into the atmosphere, volcanic eruptions and magma reservoirs deep beneath the ground also play their part.  

With all this carbon dioxide being pumped into the atmosphere, there needed to be a way of removing it otherwise the surface of the planet would rapidly overheat. 

Nature provided trees, the oceans, earth and the animals themselves as carbon sinks, or sponges. All organic life on this planet is carbon based and when plants and animals die, much of the carbon goes back into the ground where it has little impact on contributing to global warming.

Nature's fine handling of carbon dioxide in our atmosphere has served the planet very well... up until man's industrial revolution that has now thrown the earth's carbon dioxide sinks out of balance. For example, our oceans have absorbed so much carbon dioxide, they are becoming saturated and acidic. 

Many tree planting programs have been initiated over the years; originally to assist with preventing erosion, loss of biodiversity and desertification, but increasingly the benefits of these program are focused around their carbon dioxide sequestration benefits. The problem is, we've removed so many trees from this planet over the last couple of hundred years, it's going to take some time before the millions of trees planted in the last couple of years mature enough to provide sequestration benefits. Still, it's great to see the added impetus on tree planting. 

Carbon dioxide offset program via Carbonify

Artificial carbon sequestration

Humans are odd creatures - we like to dig stuff up, make it cause havoc and then try to bury it again - out of sight is out of mind. Coal and oil are great examples. We rip up the earth to get to these resources and then burn them which causes massive amounts of carbon dioxide to be released, causing global warming. 

Instead of rapidly discontinuing the use of what we know is heating our planet, researchers are trying to find other ways of defeating Nature to allow us to continue our lifestyles; or helping it deal with the excess carbon dioxide we produce - how you view the situation is up to you.

Artificial carbon sequestration refers to a number of processes whereby carbon emissions are captured at the point of product and then, well, buried. 

One proposed method is ocean sequestration whereby carbon dioxide is injected deep into the ocean, forming lakes of CO2. In theory, the carbon dioxide will stay down deep due to the pressure and temperature of the surrounding water; gradually dissolving into that water over time.

Another method is geological sequestration where the carbon dioxide is pumped into underground chambers such as old oil reservoirs, aquifers and coal seams that are unable to be mined.

Mineral sequestration is also being considered. In this method, carbon dioxide is injected into areas rich in Magnesium or Calcium. The carbon dioxide will react with those elements and combine to form calcium carbonate (limestone) and magnesium carbonate (magnesite).

Dangers of artificial carbon sequestration

We know that trees remove carbon dioxide from the atmosphere and can do it very well. They also provide us, animals and insects food and shelter. It's all the more reason for us to preserve the forests we have left and to restore ones we've destroyed. We'd be simply replacing what we have taken in an effort to restore balance. To enhance those efforts, renewable energy sources such as solar and wind power should be ramped up and everyone needs to also reduce their consumption. It's pretty simple really - consume less + more trees + renewable energy sources = less carbon dioxide = less warming. 

Artificial carbon sequestration on the other hand is costly, energy intensive, relatively untested and has no other side benefits. Not enough research has been done on the abovementioned artificial processes to determine any dangers in disposing of carbon dioxide in this way.

But nature has already done some of that research for us - an example is Lake Nyos, Cameroon, Africa. 

Carbon dioxide offset program via Carbonify

The Lake Nyos disaster

Lake Nyos is a lake in a crater of a volcano. A reservoir of magma which lies beneath the lake bubbles up carbon dioxide into the water in huge quantities. The depth and temperature of the water keeps much of this carbon dioxide at the bottom of the lake, allowing it to dissolve naturally or to bubble to the surface.

... mostly.

On August 21 1986, Lake Nyos belched a massive cloud of carbon dioxide after an eruption that killed around 1,700 people and 3,500 livestock nearby and injured thousands more. It's estimated that 1.6 million tonnes of CO2 was released in the event and as CO2 is denser than air, hugged the ground in a layer thought to be 30 metres deep for quite some time and distance before it dissipated, suffocating humans and animals in its path. The outgassing also caused large waves that destroyed trees and other vegetation close to the lake.

Lake Nyos after the eruption of carbon dioxide

Lake Nyos, usually with blue waters shown here shortly after the carbon dioxide outgassing event. 
Photo by Jack Lockwood, 1986 (U.S. Geological Survey).

Many humans and animals were suffocated in the carbon dioxide cloud that rushed down the flanks of the mountain. Photo by Jack Lockwood, 1986 (U.S. Geological Survey).

What happened at Lake Nyos could possibly happen again if we implement artificial deep injection carbon sequestration methods. Our oceans are already becoming overly acidic and ocean sequestration may increase this to a stage where marine life struggles to survive. The bottom line is that scientists just aren't sure of what the long term, let alone the short term, effects and dangers of geological, ocean and mineral sequestration are.

The earth is not a rubbish tip to be controlled by man; nature has checks and balances in place for a reason. Playing with those balances has brought us to the mess we're in today - why test  nature further? The best thing that all of us can do is to:

  • Reduce our energy and general consumption - this is the number 1 priority

  • Look more to renewable sources of energy such as solar and wind

  • Offset what we can't eliminate by the purchase of green tags based on renewable energy, plant trees or have them planted on our behalf. 

The amount of research  needed to verify various forms of artificial carbon sequestration as being safe and environmentally friendly will take many years to complete. We simply don't have that time.

Michael Bloch
"Global warming - it's our choice"