Direct Air Capture and Carbon Sequestration (DACCS) Continued

Direct Air Capture and Carbon Sequestration (DACCS) Continued

The figure below shows the results of a little experiment where a DACCS system is added to a global carbon cycle model to show what would happen if, starting in 2020, we began to remove carbon through DACCS to match the carbon emissions from burning fossils. The model begins in 1880 and runs up to 2014 using the actual human emissions of carbon, and then switches to a projection made by the IPCC for future carbon emissions.

The upper panel shows the gigatons of C from human emissions and the gigatons of C removed by DACCS, which begins in the year 2020. The lower panel shows how this change affects the global temperature change (green, in °C relative to the start), the atmospheric CO₂ concentration (red, in parts per million), and the ocean pH, which is inversely related to the acidity).

These results from a model of the global carbon cycle and the climate system shows what would happen if we used a DACCS system, starting in the year 2020 to counteract all of the carbon emissions from burning fossil fuels. The carbon removed by DACCS is shown in the upper panel along with the fossil fuel carbon emissions; it rises rapidly in the year 2020 and then tracks the carbon emissions, which effectively cancels out the carbon emissions. This results in a drop in atmospheric CO₂, a drop in temperature, and a rise in pH (higher pH values mean lower acidity).

Credit: David Bice © Penn State is licensed under CC BY-NC-SA 4.0

If we continue to burn fossil fuels as we have been (the scenario shown in the figure above), the cost of using DACCS to negate the emissions would be immense — a total of perhaps \$600 trillion by the end of the century. But if we also make drastic reductions in our carbon emissions, the cost of DACCS would be more manageable. This raises an important point — the cheapest thing to do is to switch to renewable energy (mainly wind and solar) and thus dramatically reduce our emissions. And, as we will see later, less money spent on geoengineering means more money to be spent on things like education, healthcare, and other things that improve our quality of life.