Atmospheric Carbon Dioxide: What Humans Have Added, Won't Just Go Away

Rising atmospheric carbon dioxide concentration — will it kill us all?

Even among the experts, opinions differ. The climate models, which attempt to predict the evolution of a chaotic atmospheric system, will likely always be controversial, but they indicate possible outcomes such as rises in sea level that would inundate the world's most heavily populated regions, a prediction that should give one pause for thought.

Plus, there are two other important and certain outcomes.

One is that as atmospheric carbon dioxide concentration rises it progressively impairs human mental function, as demonstrated by recent research by what one must assume are highly competent researchers at Harvard University and one of America's National Laboratories.

The other is that rising atmospheric concentration plays Hell with the biosphere, with effects that include mass species extinctions and, paradoxically, a huge increase in human population as carbon dioxide stimulates agricultural crop yields.

These facts seem now to have been generally accepted, even by major oil companies, with the result that the world is now headed for a broad-ranging set of government mandated actions to slow human-caused carbon dioxide emissions with the aim of achieving zero net emissions by 2050.

Problem is, we will still be left with a hugely elevated atmospheric carbon dioxide concentration, which will still be working its effects on the world, speeding the melting of glaciers, ice sheets and frozen soils, disrupting ecosystems and still, therefore, causing havoc.

How to respond?

One might simply hope that, in the course time, the atmospheric carbon dioxide concentration would gradually decline to where it was before the industrial revolution and the fossil fuel age. That, however, is a hope sadly to be disappointed. If there were any natural mechanism for lowering the atmospheric carbon dioxide concentration, the concentration prior to the industrial revolution would already have hit zero, all photosynthetic organisms would have died out, as would the entire animal world, dependent as it is, directly or indirectly, on photosynthetic organisms.

But, in fact, prior to the industrial revolution, atmospheric carbon dioxide concentrations were flat at around 270 part per million for hundreds of thousands of years. Yes, prior to the industrial revolution there would have been some sequestration of carbon dioxide, mainly by geological processes. But sequestration was evidently balanced by natural carbon dioxide emissions to the atmosphere resulting chiefly from volcanic eruptions. So if carbon dioxide concentrations are be reduced to something like the pre-industrial value it will be necessary for humanity to do something.

What to do?

The only answer, apparently, is CCS: carbon capture and storage.

How to capture and store carbon dioxide is a question subject to many lines of research and pilot-scale testing. Here I will consider only whether this approach to lowering atmospheric carbon dioxide concentration is economically viable:

First, how much carbon dioxide are we talking about?

Well here's the math:

The surface area of the world is ca 500 million square kilometers, or five trillion square meters.

The mass of the atmosphere is just over ten metric tons per square meter, or around 500 trillion metric tons in total. Of that, the amount of carbon dioxide that, since pre-industrial times, will have been added to the atmosphere by 2050 is:

500 trillion * (600 – 270)/1,000,000 * 1.84/1.24 = 2.45 trillion tons.

That's quite a lot, but there are methods known today for sequestering atmospheric carbon dioxide that are estimated to cost less than $100 per ton. Assuming that further research and development reduces that cost by something like a factor of ten, the cost of reducing atmospheric carbon dioxide concentration to the pre-industrial value will be around twenty-five trillion dollars, or about one quarter of the World's yearly GDP.

So, yes, adjusting the World's atmospheric carbon dioxide concentration back to normal, though costly, will be feasible, though depending on technical developments, it may take a few years.

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