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Stabilization Wedges

wedgies.jpgFar too often, discussions of efforts to mitigate the worst effects of global warming bog down under an argument that is simultaneously factual and irrelevant: there's no single solution. Solar power (or wind, or nuclear, or sonofusion) is not going to be sufficient to replace all coal and oil use. Efficiency won't improve fast enough. Sequestration can't bury enough CO2. These are all true, but only in isolation. The solution that will work comes not as a single bolt from the blue, but from a combination of multiple, varied efforts.

Princeton's Robert Socolow has captured this beautifully in a concept he calls "stabilization wedges."

With stabilization wedges, a multitude of projects, from efficiency to de-carbonization to sequestration and more, combine to reduce overall carbon emissions, a task that at times can seem impossible. Individually, the wedges are difficult but achievable. As Scolow is quoted by the Economist, this approach "decomposes a heroic challenge (eliminating the emissions in the stabilisation triangle) into a limited set of merely monumental tasks."

Socolow's model for stabilization attempts to prevent a doubling of the amount of carbon emissions by 2050 by stabilizing at the current rate of 7 gigatons of carbon/year, globally. This is sufficient to prevent the kinds of disastrous results arising from a much higher CO2 concentration, but would have to be followed by further efforts to reduce emissions once stabilized. Socolow argues that we have more than enough different ways to achieve this goal, with current technologies and practices, and that the real question becomes not "can we do it?" but "what are the best ways to do it?"

Soclow, along with research partner Stephen Pacala, introduced the concept of stabilization wedges in a 2004 paper in Science. That paper lists 15 different wedges, covering topics such as vehicle efficiency, carbon capture, and renewable power. Princeton's Carbon Mitigation Initiative (CMI) website lists the same 15 wedge options in a slightly different configuration, along with detailed discussions of what each would entail. Readers will note that the wedge items don't include changes to how urban environments are structured, adoption of sustainable agriculture (aside from "conservation tillage"), or energy efficiency of anything other than vehicles and buildings. The stabilization wedge concept, in short, is not a "bright green" approach, but a crystallization of what's possible with relatively mainstream ideas.

Socolow's argument is straightforward: we need to deploy a variety of low-carbon and carbon-reducing technologies in order to avoid doubling of CO2; we need to mitigate 7 gigatons of carbon/year; if we can adopt seven wedge options, each countering a gigaton of carbon, we can meet this goal. In this way, we don't have to adopt every possible solution, but can instead look for and deploy the ones that give us the best result for the least cost.

One particularly appealing aspect of the stabilization wedge approach is that it's relatively easy to explain. CMI provides a Flash-based presentation describing the idea for a non-specialist audience. It's a good introduction, even if the emphasis is on technology rather than behavior.

CMI takes this information and turns it into the "Stabilization Wedge Game" (PDF), a cooperative game in which players build and assess different strategies by assembling wedges. The game gives non-specialists a chance to play out some of the more difficult choices involved with carbon mitigation. The different wedge options are rated in terms of costs, effects and "challenges" (i.e., implementation difficulties). CMI asks that groups playing the game send their results back to the Initiative, as a way for the group to assess how the public grapples with these issues.

Of potentially greater interest to WorldChanging readers with a firmer grasp of climate science is Socolow's presentation at last February's "Avoiding Dangerous Climate Change" conference. We covered the conference at the time, noting with some dismay that most of the press discussions of the material focused on the "we're doomed" scenarios rather than on the scientists making "...and here's how to prevent it" presentations -- including Socolow. His presentation is based on the Science paper, but is more dynamic and includes some material not covered by the earlier work, including Fuel Displacement by Low-Carbon Electricity (e.g., grid-charged batteries for transport) and Methane Management (e.g., reducing the effects of landfill gas, cattle, rice, and natural gas).

In particular, Socolow discusses how to fund the wedges, with a carbon emission charge of $100 per ton. This would include 25 cents/gallon for gasoline, 2.2 cents/kWh for coal-based energy, and just 1 cent/kWh for natural gas -- amounts that are low enough to be palatable to a populace ready to make changes but unwilling to see dramatic sacrifice.

He also includes a slide on leapfrogging, which he calls "a path to globally coordinated mitigation."

As noted earlier, Socolow's concept of stabilization wedges was featured in a recent issue of the Economist as a viable strategy for dealing with serious global warming. It's good to see a mainstream conservative publication like the Economist taking a clear stand that anthrogenic global warming is real and will require major efforts to stop. I suspect that the Economist greatly appreciated the "we can do this" spirit of the stabilization wedge model.

I agree, but I'd take that a bit further: what is most appealing to me about stabilization wedges is that it demonstrates that we don't need radical improvements in our technologies and changes to our behavior to be able to avoid the worst-case scenarios. This means that improvements to our technologies and changes to our behavior -- all of which are well-within our capabilities -- have the potential therefore to make things better. If Socolow is correct, and I believe that he is, we aren't yet facing a world in which doing the very best we can means barely hanging on. Instead, we are in a position now to make resolute and meaningful advances, thereby keeping us from disaster and laying the groundwork for even greater transformations.


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» Energy Policy and Markets: 2006-01-10 from Winds of Change.NET
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Comments (3)


Great post, thanks. What you reiterate in your first paragraph just can't be said too many times. I think this model is a good one, I especially like the connection to the low-tech but extremely powerful tool of the wedge - one of humankind's earliest. One thought I had reading this: although like a single technology, a single entity cannot save us, we really have no idea what would be possible with strong federal leadership. It's too much to hope for right now, but these things change. My guess is that once implemented, techniques and technologies to fight this battle will be both closer and easier than we think.

There are several problems with this:

(1) Most projections show world energy use more than doubling from 2000 to 2050; the renewables and efficiency improvements required to maintain ONLY a doubling of carbon emissions ALREADY builds in the assumption of wide-scale adoption of many of Socolow's wedges through both natural economic forces and necessary government regulation, for example carbon emissions limits.

Now certainly the wedge technologies could be greatly expanded to reduce carbon emissions further - but in a sense there's some double counting going on here that makes the problem significantly more daunting than Socolow's presentation would suggest.

(2) The "wedge" technologies cited that are not going to be contributing through natural economic forces are either technically feasible but very costly, or still really technically infeasible. As Marty Hoffert has pointed out, when "Pacala and Socolow claim that 'Humanity already possesses the fundamental scientific, technical, and industrial know-how to solve the climate problem for the next half century.', [t]his might be the case in the sense that humanity had the know-how to build nuclear weapons in the late 30s or go to the Moon in the 50s. But it took the Manhattan and Apollo programs to make it so."

Socolow's wedges are stopgaps. Past energy transitions have involved essentially wholesale switching of the vast majority of usage - from wood to coal, from coal to oil - as is typical of many technological areas: there's a natural logistic curve of adoption of a new technology once it's "ready" according to economic and technical criteria; there will be such a new energy technology, the question right now is mainly, what will it be. Socolow's arguments don't really help us figure that out.


I have worked on wedge technologies a long time, and some of them have worked very well, but during this time it has always been in the back of my mind that what they are doing is allowing us to more efficiently do stuff that shouldn't be done at all.

An obvious example- all those unwanted catalogs that you and I just shovel into the recycling bin. We can all add a thousand others to the list.

New technology is a lot of fun and relatively easy to develop, but what we really need is to set rational priorities on what to do that include all the bad effects that we normally ignore. Then we would not do ever so many things at all, and THAT would really cut down our corrupting influence on the environment- and make us all better off.


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