Thursday, March 14, 2013
What I Learned About Climate Change this Year
I just finished teaching a two-quarter class on climate change, and here is my most important takeaway. Going in, I knew the main aspects of the science and how much risk we face. I also knew the main policy levers and, in general terms, the pluses and minuses of each. What I didn’t know then, but know now, is the enormous mismatch between the obligatory greenhouse gas mitigation timetable and the energy transition timetable.
The first is about the targets we need to reach in order to keep climate change unpleasant but manageable. For a very stringent version, see this analysis by Kevin Anderson. Here is one of his mitigation scenarios:
This is a set of global pathways. Reductions begin in 2020 (riotous optimism in my opinion, but why not?) and reach their goal by 2040 or so at the latest. The different colored lines represent different assumptions about climate sensitivity. If we're lucky and the least sensitive relationships apply, we get the purple line. If the news on the science front turns out to be worse, we could end up with the red or blue, which basically fall off a cliff in 2020. That is not a representation of policy but catastrophe. It is unimaginable, in fact. So stick to your optimism and color the science purple or green.
The second timetable is about the replacement of carbon-based energy and the infrastructure it rests on with carbon-free energy, along with its infrastructure, and expanded to meet the needs of the hundreds of millions of people who lack adequate energy supplies today but will acquire them tomorrow. I haven’t seen a particular visualization that jumps out at me, but everyone who studies energy systems agrees that it will take many decades to innovate, deploy and scale up new energy sources, along with the investments we need to make to achieve greater efficiencies in using energy to meet human needs.
If our reduction in fossil fuel use is limited to the progress we make in substituting non-carbon energy, we’re cooked. Literally.
Before teaching this course I didn’t realize how bad this mismatch truly is.
So, if we want to avoid carbonapocalypse, we will have to do without some stuff for a while. This was one motivation for my Green Keynesianism post: one of the goals of economic policy around climate and the macroeconomy is to make it possible for people to do the kind of expenditure-switching that can maintain incomes and employment—and quality of life—even as the energy-dependent part of our economy is pinched.
It is also behind the posts I’ve written to more carefully distinguish mitigation from adaptation in carbon policy. Unless we turn to geoengineering or sequestration, there is only one form of mitigation: leaving fossil fuels in the ground. Supplying clean energy and improving the efficiency of energy use are not mitigation. They can lead to mitigation if they result in more carbon staying put in the lithosphere, but only then, and only to that extent. This is important not because I like to split hairs, but because energy transition alone will not be enough to do the job. To understand this, and to feel it deeply enough to get you to do something about it, you need to have an absolutely clear sense of what the job actually is.
To repeat what I’ve said before, none of the above should be taken as criticism of all the activism and policy intelligence around energy transition. We absolutely need to replace carbon-based fuels with clean ones and revolutionize our heating, transportation and other systems as quickly and massively as possible. This is for two tightly connected reasons, to preserve and enhance our quality of life in the face of the climate challenge and to promote the political will we must somehow summon to enact the restrictions that will force most of the carbon now buried to stay buried. Adaptation, which is what energy transition comes down to, is not a dirty word. The problem is, mitigation demands more.