Saturday, January 19, 2013

Mitigation Versus Adaptation in Climate Change


Today I will take a stab at dispelling what I think is widespread confusion over what constitutes mitigating climate change, as against adapting to it.  Both are necessary, of course, but effective policy depends on understanding which is which.

Begin with the following stylized fact: reducing the severity of future climate change is essentially about keeping fossil fuels in the ground.  It is true that there are some benefits from tweaking carbon exchange (the carbon cycle that operates across the atmosphere and terrestrial and marine ecosystems)—for instance, by planting a forest—but the impacts are relatively small (not big enough to do most of the job) and of uncertain duration.  And someday there might be a feasible method for pulling the carbon out of the fuels we burn and re-sequestering it for near-eternity.  But for now these options are of limited value.  As Carbon Tracker noted last year, about 80% of hydrocarbon reserves have to be foregone if we are to achieve a reasonable likelihood of limiting warming to 2º C.

This gives us a rough and ready definition of mitigation: reducing the extraction of fossil fuels.  Everything else is adaptation.

But wait.  What about renewable energy?  Efficiency improvements?  Aren’t these about reducing the buildup of greenhouse gases?

To answer this it helps to distinguish between two types of adaptation: adaptation to climate change and adaptation to climate change policy.  An example of the first is reinforcing seawalls and dikes to minimize storm surges despite rising sea levels.  An example of the second is a wind farm.

A wind farm does not reduce carbon emissions.  What it does is to preserve energy services despite a decline in the rate of fossil fuel extraction.  In other words, it reduces the cost society has to pay in order to take the action that actually mitigates climate change, leaving the hydrocarbons in the ground.

The distinction is important.  Imagine a fossil fuel reserve with two uses, generating electricity and powering an industrial process.  Suppose we invest in a wind farm to replace the use of the fuel in electrical generation.  Now demand for the fuel drops, which lowers its price.  This may well lead to an increase in its industrial use—not fully offsetting of course, but partially offsetting.  The impact of the wind farm on climate mitigation is entirely measured by how much total fuel extraction is reduced, not by how much energy the farm produces.  Its principal function is to enable us to continue benefiting from electricity in the absence of burning fuels.

If you look at it this way, the accounting for carbon capping systems becomes much simpler.  It’s all about how much fuel (measured in terms of carbon equivalents) you do or don’t burn.  Everything else is about how to live with the consequences, both from limiting the use of fuels and from having to deal with climate change.  This is why a policy regime that offsets reductions in fuel combustion by granting credits to all sorts of green production investments is essentially trafficking in loopholes.