Public Interest Research Centre - PIRC

Since James Hansen's recent assertion that we've already passed safe levels of greenhouse gases, there's been a lot of talk about "drawdown".

Imagine it like limbo dancing if you will… the dancer representing human emissions, standing 8 feet tall say (1 foot for every billion tonnes of carbon) and the limbo pole, 4 feet high, represents the Earth’s carbon sinks (how much carbon the Earth soaks up every year).

Now, traditional policy, 'stabilisation', says all you need to do is come in just a fraction under the pole. Then human emissions are matched by the Earth’s absorption (both at 4)… and so atmospheric concentrations are 'stable'.

What this new analysis says is that we have to lower the total amount of carbon dioxide in the atmosphere - reducing emissions is no longer enough, we have to now reduce concentrations, that means we have to reduce our emissions to well below the level that Earth can reabsorb. In the Limbo analogy we can’t just come in fractionally under the pole anymore, we need clearance between the dancer and the pole, and the more clearance the better… the greater the clearance, the faster reductions in atmospheric concentrations occur...

The complication is, that no matter how much politicians tell us to the contrary, we haven’t even started the dance yet… and every year that passes, every year we twiddle our thumbs at international negotiations the dancer grows taller, about 3 inches every year (much taller than we thought the dancer would grow!). But not only is the dancer growing, the pole is also falling… as the Earth warms the carbon sinks reduce… as the pole drops it not only makes it harder for the dancer to get under, it also reduces the total amount of clearance they can hope to achieve...

And we only get one chance to play the game.

So all this talk of "sequestration" through afforestation, biochar (terra pretta) or air capture etc. it's all just a method of slowing the pole's descent (or even possibly raising it!), by enhancing the earth's ability to absorb carbon.

Restorative processes that also store carbon are a good thing, so reforestation and afforestation, carried out responsibly, are great. Air capture however, appears to have problems.... the main one being cost. In a world of ever increasing fossil fuel prices, it's going to be much cheaper to decarbonise an economy rather the suck millions of tonnes of carbon dioxide out of the air, compress it, transport it and store it permanently underground.

But more on that another time...