How does artificial carbon sequestration work?

artificial carbon sequestration

Artificial is a term that we typically take to mean fake. So why is it being used to prefix a vital process? And how does artificial carbon sequestration work?

Indeed, artificial carbon sequestration is a phrase being tossed around all the more frequently these days, be it on the evening news or within classrooms. It is a particular favourite amongst the fossil fuel industry, who are quick to promote the process because of its ability to counteract our emissions.1 They claim that vehicles and power-plants could continue burning fossil fuels indefinitely, with the resulting carbon emissions being captured and stored before entering the atmosphere.

It certainly paints a pleasant picture. Yet, bear in mind this is the same flawed logic behind the failed idea of so-called “clean coal”.2

So what is artificial carbon sequestration, and more importantly, how does it work?

Artificial Carbon Sequestration: an overview

Artificial carbon sequestration (ACS) refers to the anthropogenic (human-induced) enhancement of the earth’s own natural carbon capture and storage process. By bolstering the age-old system of removing carbon dioxide – a greenhouse gas – from the atmosphere, scientists propose ACS as a strategy to prevent catastrophic global warming.3

How does it work?

Consider the process of natural carbon sequestration. Forests are burned, a volcano erupts or an animal exhales. Carbon dioxide (CO2) is released into the air. Plants then absorb this CO2 through a process called photosynthesis. The plant uses the CO2 for growth, until eventually it becomes stored in the soil as organic matter. At the same time, more atmospheric CO2 is mixing with rainwater to create carbonic acid, which slowly dissolves rock through a process called chemical weathering. Eventually the dissolved rock reaches the ocean, effectively trapping the CO2 deep underwater.1

The problem, however, is that some human activities mean we are now pumping out far more CO2 than can be sequestered at the natural rate. The outcome is rising global temperatures. Might it still be possible to re-establish the planet’s carbon sink? Cue artificial sequestration.

In its most basic form, ACS involves planting more trees (afforestation) in order to increase the rate of CO2 absorption from the atmosphere.4 Enhanced chemical weathering  is another proposed option; this involves speeding up the aforementioned natural process by spreading finely crushed rock on farmland, or over the ocean.5

There are various other forms of artificial sequestration.6 However, all share the same end goal: increase the natural rate of CO2 uptake, and offset global emissions.

Looking ahead

Can we put faith in this strategy? There are mixed views within the scientific community as to the overall potential of ACS as a global warming solution. We cannot forget that CO2 is not the only greenhouse gas contributing to our global problem.

But from what evidence is available, in the form of the earth’s age-old carbon cycle, it is certainly a project worth pursuing.

 

  1. Oeklers, E.H. and Cole, D.R. (2008) Carbon dioxide sequestration: a solution to the global problem. Elements 4, 305-310.
  2. Pierre-Louis (2017) There’s no such thing as clean coal [Online] Popular Science. [Accessed April 2020]
  3. IPCC. (2018) Global Warming of 1.5˚C: Summary for policy makers. IPCC Special Report. ISBN 978-92-9169-151-7.
  4. Bastin, J., Finegold, Y., Garcia, C., Mollicone, D., Rezende, M., Routh, D., Zohner, M. and Crowther, T.W. (2019) The global tree restoration potential. Science, 365(6448), 76-79.
  5. Strefler, J., Amann, T., Bauer, N., Kriegler, E. and Hartmann, J. (2018) Potential and costs of carbon dioxide removal by enhanced weathering of rocks. Environmental Research, 13(3).
  6. Nogia, P., Sidhu, G.K., Mehrotra, R. and Mehrotra, S. (2016) Capturing atmospheric carbon: biological and nonbiological methods. International Journal of Low-Carbon Technologies, 11(2), 266-274.

 

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