13 April 2007

Fight global warming by chopping down trees?

From the current issue of the Economist (subscription):

A climate model suggests that chopping down the Earth's trees would help fight global warming. … The reason for this is that trees affect the world's temperature by means other than the carbon they sequester. For instance forests, being generally green and bristly things, remain quite a dark shade even after a blizzard.
The article is reporting on a study led by Govindasamy Bala, of the Lawrence Livermore National Laboratory, in California, and it doesn’t mention many other ways in which trees might warm the climate. For me the implications are that, with our very limited knowledge of the causes of climate change, we ought to target not the ways in which we currently think we can stabilize the climate, but the goal of climate stability itself. We simply don’t know enough about the mechanisms underlying climate change to make policy today on how to stabilize the climate.

The scientific complexities of climate change are analogous to those of a social system, and our policymaking cannot cope with great complexity. It cannot reliably identify the cause and effect in complex systems, and it certainly cannot cope with rapidly expanding knowledge, nor with the diversity inherent in large geographical areas. It’s too quick to identify a causal relationship, and then base policy on it. The Kyoto agreement is one such response to climate change. Whether Dr Bala’s study is right or wrong on the question of trees and climate change, is not the point. What is crucial is that our policymakers have some degree of humility, and create policies that don’t assume they know the entire truth.

Instead of promoting what are thought to be the means by which a goal is to be achieved, they should reward the society’s desired outcome. When it comes to climate change, instead of rewarding the planting of trees, or whatever seems, with current science, to be ways of reducing our net emissions of greenhouse gases, it should target climate stability, and let the market decide on the best ways of achieving that goal. These ways will not be obvious, and they will vary with time according to circumstances that we cannot anticipate. Rewarding successful achievement of society’s goals, as under a Social Policy Bond regime, encourages a wide range people to find diverse, adaptive and efficient ways of achieving social and environmental goals. Leaving such an exploratory process in the hands of politicians and bureaucrats just isn’t going to work: society and the environmental challenges are now just too complex for an approach that was devised (and worked very well) in the late 19th century.

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