The Bathtub

On the eve of Paris, I would like to share an analogy first put forward by K. Eric Drexler in his book Radical Abundance, just so that everyone understands just how serious our predicament has become.

The earth’s atmosphere can be compared to a bathtub. CO2 entering the atmosphere is like the cold tap (or faucet) of the bath, filling it with water, and CO2 leaving the atmosphere is like the plughole, draining water from the bath.

Before the industrial revolution, the natural balance between the sources and drains of atmospheric CO2 was holding the level of CO2 in the atmosphere at 280 parts per million by volume, a level within a natural cyclic variation in CO2 concentration over geological timeframes.

The industrial revolution was like turning on the hot tap, topping up the water level in the bathtub, such that the level of CO2 in the atmosphere now exceeds 400 ppm.

Even if we reduce the flow of the hot tap (the burning of fossil fuels), even if all the world’s governments agreed to turn the tap off completely, we would have done NOTHING to lower the now raised level of water in the tub. The planet will keep on getting hotter due to greenhouse warming (accelerated by the release of methane trapped in permafrost) because nothing has been done to remove the greenhouse itself.

We would require all the energy, released in the burning of fossil fuels over the entire period of industrialisation, to convert the additional CO2 in the atmosphere back into hydrocarbons and oxygen. That would take a very big army of tree planters, or a lot of solar cells and windfarms producing the energy to make more solar cells and wind farms. And a whole lot of time we don’t really have.

In the short term then, we need to extract and concentrate the excess CO2 from the atmosphere and simply store it away while we find the time to convert it back into hydrocarbons (and wood). There are plenty of voids in the earth’s crust that once had oil and gas in them in which to store the (liquefied) CO2. What we need however are efficient pumps to effect this extraction and storage, and Eric has a masterful plan to develop a manufacturing technology that could achieve this.