The way back to 280 ppm

Concentration of carbon dioxide in the atmosphere reached 394.97ppm at Mauna Loa in May — 41% above the 280ppm it had been for thousands of years before the Industrial Revolution started.

Given the dangers of global warming, carbon dioxide needs to get back to 280ppm. Emission cuts alone will not be able to accomplish this, so what more can be done?

Emissions cut 80% by 2020,
Sam Carana, March 18, 2008

Large drops in carbon dioxide have taken place in history, and are attributed to weathering, i.e. rocks breaking down and carbonates being deposited on ocean floors. However, it takes nature many, many years to do this. To make this happen at accelerated rates, carbon dioxide removal methods can be deployed that are typically referred to as mineral carbonation and accelerated weathering.

At first glance, one may suggest implementation of policies such as cap-and-trade or cap and capture to make those who put carbon into the atmosphere pay for its removal. More effective, though, is a combination of two types of feebates, working separately, yet complimentary, to get emissions cut 80% by 2020 and carbon dioxide on the way back to 280ppm.

Many carbon dioxide removal methods are energy-intensive. As long as the energy used is expensive and polluting, not much can be achieved. A rapid shift to clean energy is necessary, which is best facilitated through energy feebates.

As the number of solar and wind facilities grows, large amounts of clean electricity will become available at off-peak hours, when there's little demand for electricity. This will make such electricity cheap, bringing down the cost of methods such as enhanced weathering, which can take place at off-peak hours. Such energy will also make carbon dioxide removal more effective, since the energy is clean to start with.

Energy feebates as pictured above can best clean up energy, while other feebates can best raise revenue for carbon dioxide removal.

Energy feebates can phase themselves out, completing the necessary shift to clean energy within a decade. Carbon dioxide removal will need to continue for much longer, so funding will need to be raised from other sources, such as sales of livestock products, nitrogen fertilizers and Portland cement.

A range of methods to remove carbon dioxide would be eligible for funding under such feebates. To be eligible for rebates, methods merely need to be safe and remove carbon dioxide. Methods could remove carbon dioxide from the atmosphere and/or from the oceans.

Rebates favor methods that also have commercial viability. In case of accelerated weathering, this will favor production of building materials, road pavement, etc. Such methods could include water desalination and pumping of water into deserts, in efforts to achieve more vegetation growth. Selling a forest where once was a desert could similarly attract rebates.

Some methods will be immediately viable, such as afforestation and biochar burial. It may take some time for methods such as enhanced weathering to become economically viable, but when they do, they can take over where afforestation has exhausted its potential to get carbon dioxide back to 280ppm.

For further discussion, also see Towards a Sustainable Economy