Breaking: Socolow reaffirms 2004 ‘wedges’ paper, urges aggressive low-carbon deployment ASAP

Still asserts “existing technologies could affordably limit warming”

In 2004, Princeton Profs Socolow and Pacala published a paper in Science, “Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies.” The abstract read:

Humanity already possesses the fundamental scientific, technical, and industrial know-how to solve the carbon and climate problem for the next half-century. A portfolio of technologies now exists to meet the world’s energy needs over the next 50 years and limit atmospheric CO2 to a trajectory that avoids a doubling of the preindustrial concentration. Every element in this portfolio has passed beyond the laboratory bench and demonstration project; many are already implemented somewhere at full industrial scale. Although no element is a credible candidate for doing the entire job (or even half the job) by itself, the portfolio as a whole is large enough that not every element has to be used.

I spoke to Socolow today at length, and he stands behind every word of that — including the carefully-worded title. Indeed, if Socolow were king, he told me, he’d start deploying some 8 wedges immediately. A wedge is a strategy and/or technology that over a period of a few decades ultimately reduces projected global carbon emissions by one billion metric tons per year (see Princeton website here).

Socolow told me we “need a rising CO2 price” that gets to a serious level in 10 years. What is serious? “$50 to $100 a ton of CO2.”


You’d never know any of that from reading the false narrative industrial complex today. They jumped all over a piece in National Geographic News by a reporter who apparently heard a recent talk of Socolow’s, but perhaps didn’t quite understand precisely what Socolow meant.

Socolow was not disavowing his original analysis in the least — nor providing any comfort to the do-little breakthrough bunch. Quite the reverse. He thinks they are members of a “Cargo Cult” waiting for “pie in the sky” answers (see “The breakthrough technology illusion”).

UPDATE: This post has been updated to included comments by Socolow. Also, Socolow sent me (and Revkin) a long reply to the various pieces published, which I reprint in full at the end.If there is any doubt as to what Socolow believes today, he wanted me to remind people he is a signatory to the recent National Academy of Science report that calls on nation to “substantially reduce greenhouse gas emissions” starting ASAP.

The wedges look simple, but they aren’t, and if you don’t spend time reading the supplementary material and talking to Socolow, you’ll probably get it wrong. Folks like Roger Pielke, Jr., who has teamed with the hard-core anti-science crowd to spread disinformation, have misanalyzed them completely (see here). Socolow dismissed Pielke’s latest attack on me in his interview and his written reply.

I have written a great deal about the wedges over the years because, despite their analytical complexities, they simplify the process of describing what needs to be done. I have spent a lot of time talking to Socolow. We agree on the vast majority of things, but take a slightly different view of the science, which I’ll discuss below.


NYT blogger Andy Revkin seems so intent on avoiding any endorsement of strong action now that he writes stuff like this:

Some climate campaigners, notably Joe Romm, warned that the original wedges energy template was inadequate, but maintained that the core notion “” that existing technologies could affordably limit warming “” was valid.

I asked Socolow point blank if he still believed “existing technologies could affordably limit warming” — and he said yes. Of course he supports more on R&D, as he always did (see below). Everybody supports more R&D (well, other than most top conservatives politicians), and some of us have spent decades pushing for it.

The issue is whether, in addition to R&D, you understand that limiting global warming requires aggressive deployment of every last bit of low-carbon technology that you have today starting now — and that this is really more important than the R&D since if you don’t do it, all the R&D in the world can’t help you. Also, deployment is probably as important if not more so for lowering the cost of low-carbon technology than basic research.

Revkin notes that he included the wedges in a 2006 article, but writes:

But along with the wedges, which we described as near-term, I added a second column denoting what would have to happen simultaneously to build the capacity to take the carbon out of a growing global energy menu. Without both, all that’s accomplished is building a campaign around an entirely inadequate set of policies that distract from the scope of the necessary “energy quest.”

The wedges aren’t “near-term.” For Socolow they are the central activity of the next 50 years. To call them “entirely inadequate” is to miss the point. Aggressive deployment starting now is the sine qua non — without this, no livable climate.

It’s important to remember what Socolow wrote in 2004:

The debate in the current literature about stabilizing atmospheric CO2 at less than a doubling of the preindustrial concentration has led to needless confusion about current options for mitigation. On one side, the Intergovernmental Panel on Climate Change (IPCC) has claimed that “technologies that exist in operation or pilot stage today” are sufficient to follow a less-than-doubling trajectory “over the next hundred years or more” [(1), p. 8]. On the other side, a recent review in Science asserts that the IPCC claim demonstrates “misperceptions of technological readiness” and calls for “revolutionary changes” in mitigation technology, such as fusion, space-based solar electricity, and artificial photosynthesis (2). We agree that fundamental research is vital to develop the revolutionary mitigation strategies needed in the second half of this century and beyond. But it is important not to become beguiled by the possibility of revolutionary technology. Humanity can solve the carbon and climate problem in the first half of this century simply by scaling up what we already know how to do.

UPDATE: Socolow told me the only word he would delete in the paper is “simply.”

What Do We Mean by “Solving the Carbon and Climate Problem for the Next Half-Century”?

Proposals to limit atmospheric CO2 to a concentration that would prevent most damaging climate change have focused on a goal of 500 ± 50 parts per million (ppm), or less than double the preindustrial concentration of 280 ppm (3–7)….


In confronting the problem of greenhouse warming, the choice today is between action and delay. Here, we presented a part of the case for action by identifying a set of options that have the capacity to provide the seven stabilization wedges and solve the climate problem for the next half-century. None of the options is a pipe dream or an unproven idea…. Every one of these options is already implemented at an industrial scale and could be scaled up further over 50 years to provide at least one wedge.

So Socolow and Pacala was shooting at 500 ± 50 ppm CO2 with his 7 wedges. Now he would be over-delighted with 8 wedges and staying below 550 ppm.


His priority back in 2004 — and still today — is avoiding the catastrophic warming we face on our business-as-usual emissions path of 5°C to 6°C (9 to 11 °F). That’s why he says we need to start aggressive technology deployment now, along with a CO2 price that rises within a decade to serious levels of “$50 to $100 a ton of CO2.”

He strongly supports R&D. That’s why the article says, “We agree that fundamental research is vital to develop the revolutionary mitigation strategies needed in the second half of this century and beyond.” But he scoffs at the notion that we should delay deployment now waiting for those revolutions — and, as noted, called those who see those hoped-for revolutions as a replacement for action now as members of a “cargo cult” [who, as Wikipedia notes, believe in “obtaining the material wealth (the ‘cargo’) of the advanced culture through magic and religious rituals and practices”].

Indeed, he called this view “doubly deceptive.” It requires believing the “pie in the sky” stuff will be available sometime soon and that if it becomes available, “we can take the other stuff off the table.” He said that was “quadratically unlikely.”

One key point Socolow makes that the breakthrough bunch don’t understand is that “very few people working on zero-carbon solutions, like fusion or air capture, expect it to be cheap.” Again, let’s all hope there are breakthroughs and let’s all push to invest more money in them, but we can’t take our eyes off the prize of deployment, deployment, deployment.

Finally, let me touch on the one area where we disagree a bit. Socolow thinks that a 3°C target is the only realistic one that we can achieve now. That may well be true politically. I have tried to make as clear as possible that what is required to stabilize at 2°C is not currently politically possible (though that is also true of the 3°C target). Remember, 1 wedge of nuclear power would require adding globally, an average of 14 new plants each year, while building another 7 plants a year to replace those that will be retired, sustained for five decades. The scale is staggering for any wedge — one million large (2 MW peak) wind turbines. I know of nobody who said that deploying even seven wedges would be easy.

Socolow believes we can afford to pursue the 3°C target until we know with far greater confidence that it is untenable. I don’t really buy that. He is it certainly aware of the risks of the carbon-cycle feedbacks, but his knowledge about the degree of difficulty of achieving even 8 wedges in the coming decades leads him to believe that pressing for substantially more may be counterproductive. He acknowledges that is primarily a political judgment, but notes that recent events at the national and international level would seem to support his view.

If you want a 2°C target, then the world needs to do some combination of the dozen or so wedges laid out here: “The full global warming solution: How the world can stabilize at 350 to 450 ppm.” Not bloody likely, for sure, but a report by the International Energy Agency came to almost exactly the same conclusion as I did, and has relatively similar wedges, so I view that as a vindication of the overall analysis.

Finally, in practice, my differences with Socolow are, as we both agreed, closer to counting angels dancing on the head of a pin — especially compared to our mega-differences with the do-little crowd. I would gladly have ‘settled’ for pursuing 7 wedges starting in 2005 as Socolow and Pacala proposed then, but which the deniers and the breakthrough bunch opposed fiercely. And while I’d love to start 12 wedges now, I would again be utterly overjoyed if the world started 8 now, since it gives the world a fighting chance, something that the cargo cult strategy does not.

Similarly, while Socolow would start with 8 wedges now, he views the interaction between science and deployment policy as “iterative.” If the scientific case for more rapid deployment becomes significantly stronger, he’d quickly start adding wedges. My guess is that he would be adding wedges pretty darn soon — certainly by the time the tundra actually starts emitting significant amounts of methane (see “NSIDC bombshell: Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100”). Again, if we start with 8 wedges now, then we aren’t hopelessly lost in the 2020s as we are likely to be if we keep doing nothing.

Deployment, deployment, R&D, deployment, deployment.

Here is the statement Socolow sent to me and to Revkin (italics added):

Re the National Geographic blog by Doug Struck.

A. Look closely at what is in quotes, which generally comes from my slides, and what is not in quotes. What is not in quotes is just enough “off” in several places to result in my messages being misconstrued. I have given a similar talk about ten times, starting in December 2010, and this is the first time that I am aware of that anyone in the audience so misunderstood me. I see three places where what is being attributed to me is “off.”

  • “It was a mistake, he now says.” Steve Pacala’s and my wedges paper was not a mistake. It made a useful contribution to the conversation of the day. Recall that we wrote it at a time when the dominant message from the Bush Administration was that there were no available tools to deal adequately with climate change. I have repeated maybe a thousand times what I heard Spencer Abraham, Secretary of Energy, say to a large audience in Alexandria. Virginia, early in 2004. Paraphrasing, “it will take a discovery akin to the discovery of electricity” to deal with climate change. Our paper said we had the tools to get started, indeed the tools to “solve the climate problem for the next 50 years,” which our paper defined as achieving emissions 50 years from now no greater than today. I felt then and feel now that this is the right target for a world effort. I don’t disown any aspect of the wedges paper.
  • “The wedges paper made people relax.” I do not recognize this thought. My point is that the wedges [paper] made some people conclude, not surprisingly, that if we could achieve X, we could surely achieve more than X. Specifically, in language developed after our paper, the path we laid out (constant emissions for 50 years, emissions at stabilization levels after a second 50 years) was associated with “3 degrees,” and there was broad commitment to “2 degrees,” which was identified with an emissions rate of only half the current one in 50 years. In language that may be excessively colorful, I called this being “outflanked.” But no one that I know of became relaxed when they absorbed the wedges message.
  • “Well-intentioned groups misused the wedges theory.” I don’t recognize this thought. I myself contributed the Figure that accompanied Bill McKibben’s article in National Geographic that showed 12 wedges (seven wedges had grown to eight to keep emissions level, because of emissions growth post-2006 and the final four wedges drove emissions to half their current levels), to enlist the wedges image on behalf of a discussion of a two-degree future. I am not aware of anyone misusing the theory.

B. I did say “The job went from impossible to easy.” I said (on the same slide) that “psychologists are not surprised,” invoking cognitive dissonance. All of us are more comfortable with believing that any given job is impossible or easy than hard. I then go on to say that the job is hard. I think almost everyone knows that. Every wedge was and is a monumental undertaking. The political discourse tends not to go there.

C. I did say that there was and still is a widely held belief that the entire job of dealing with climate change over the next 50 years can be accomplished with energy efficiency and renewables. I don’t share this belief. The fossil fuel industries are formidable competitors. One of the points of Steve’s and my wedges paper was that we would need contributions from many of the available option. Our paper was a call for dialog among antagonists. We specifically identified CO2 capture and storage as a central element in climate strategy, in large part because it represents a way of aligning the interests of the fossil fuel industries with the objective of climate change.

Re the Revkin blog

Andy Revkin revisits the multi-step process that Steve’s and my paper envisioned. Our two steps toward stabilization were each 50 years long, as described in item 1b above. We strongly advocated R&D to develop further options. We also affirmed that R&D would be required to implement the wedges listed in our paper and to bring down their costs. Eventually, just about everyone involved became comfortable with the idea that both evolutionary deployment of what we already understand and revolutionary new knowledge were essential. I hope we don’t need to get mired in this non-issue again.

Andy refers to reducing emissions below today’s level as “the real heavy lifting.” By implication, holding emissions 50 years out to today’s level is not heavy lifting. Andy calls it “merely” the first step. I think this could be construed as an example of finding achieving eight wedges “easy.” On the contrary, both are heavy lifting. Each successive wedge represents a deeper change in today’s global economic trajectory than the one before, on the one hand, but gaining commitment and getting policies right and sorting through alternatives within the various wedges are all formidable assignments, and arguably this aspect of achieving wedges becomes a little less monumental with successive wedges. Somewhere, there is an optimum pace. Pacala and I were thinking about optimum pace when we drew our Figure.

For the record, there was no National Geographic interview. I gave a talk and apparently Doug Struck was in the audience. I left quite promptly after the talk, speaking briefly with several people, perhaps including him.

Re Pielke

Pielke writes “it is hard to imagine that Socolow’s comments can be in reference to anyone other than Romm.” I am not a close follower of Joe Romm’s blog. I did not have him in mind.

It is distressing to see so much animus among people who have common goals. The message of Steve’s and my wedges paper was, above all, ecumenical.

If Revkin supports 450 to 500 ppm, I’d love to see his solution, rather than his umpteenth critique of those of us who understand, like Socolow, that the only chance we have at getting anywhere near 500 is aggressive deployment of multiple wedges starting now.

It is true that Pielke claimed on this very blog to have a similar goal to me — stabilizing at 450 to 500 ppm. But he simply refuses to propose a solution that could possibly get us on that path and he vilifies those of us who do. Tobis directs us to this devastating review of Pielke’s latest book in IEEE Spectrum:

Significantly, Pielke agrees with the rest of his field on the need to stop emitting carbon dioxide and to stabilize its concentration in the atmosphere at somewhere between 350 and 500 parts per million; he just doesn’t want scientists to tell the rest of us how to get there.And so with all the “debunking” of prominent science, by the book’s end his readers won’t have learned very much at all. If you didn’t know that there were uncertainties in climate science before, then yes, you will definitely know that now. Pielke’s actual “fix,” on the other hand, comes so late in the book and is so poorly highlighted that it might not get noticed at all.

What is that fix? Well, it involves an obscenely low price on carbon (US $5 per metric ton) that will pay for further innovations in renewable energy. Other than that, Pielke advocates setting specific goals, monitoring progress, and focusing on technology advancement. Yawn.

If Pielke’s first tenet is the completely unrealistic and potentially counterproductive divorce of science from policy, his second, as evidenced by the meager carbon price, seems to be aiming low in the name of political expediency. He suggests five bucks only because it seems feasible and cites the support of Exxon Mobil’s CEO as evidence. Seriously, Exxon Mobil. “The precise amount of the tax itself””whether $5 per metric ton, or $10, or only $3″”is less important than that the tax be implemented at the highest price politically possible,” Pielke writes.

Such “pragmatism” amounts to bargaining ourselves down in advance of the bargaining that we have to do with others. Pielke’s carbon price will force fossil fuel companies like ExxonMobil to do absolutely nothing differently. Pielke admits this, noting that the point is simply to raise money for renewable energy technology innovation. Such a path, though, ignores the vast scientific consensus that we need to start lowering emissions yesterday. Even if his carbon tax could raise $150 billion per year, as Pielke suggests, the pace of innovation can’t match the pace of current emissions and subsequent temperature and sea level rise, ocean acidification, and various other problems. At its root, Pielke’s climate fix is to do almost nothing.

Sounds like the very model of a modern cargo cultist.