The Earth's Climate — Rethinking "Rethinking Wedges"

Rethinking Wedges is a paper which appeared recently in the journal Environmental Research Letters (Vol. 8, No. 1, January-March, 2013). I was going to title this post Is Humanity Fucked?, but chose to refrain from such vulgar sensationalism. While the title I chose is faithful to the subject matter, the title I did not use is more faithful to its spirit.

I will have to go through a complex argument, so I hope you have the time and patience to follow the text. Let's get right to it. We shall require two technical terms, one from the paper and one of my own devising. First, what is a climate stabilization wedge?

In 2004, Pacala and Socolow published a study in Science arguing that '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'. Specifically, they presented 15 options for stabilization wedges that would grow linearly from zero to 1 Gt [gigaton, = 10¹² kilograms] of carbon emissions avoided per year over 50 years.

The solution to the carbon and climate problem, they asserted, was to deploy the technologies and/or lifestyle changes necessary to fill all seven wedges of the stabilization triangle. They claimed this would offset the growth of emissions and put us on a trajectory to stabilize atmospheric CO₂ concentration at 500 ppm if emissions decreased sharply in the second half of the 21st century.

Implementing any stabilization wedge presents a considerable, daunting challenge for humanity. You can read the original paper (pdf) to see what I mean.

The target for avoiding dangerous climate change in Pacala and Socolow (2004) was 500 ppm (parts-per-million) of CO₂ in the atmosphere, with a concomitant warming of 2 °C. This allows us to define the term fucked.

Humanity is fucked if there is no hope of avoiding a climate regime which makes the Earth uninhabitable for large, big-brained, bipedal, primates like Homo sapiens. Such an outcome will eventually come to pass if CO₂ in the atmosphere exceeds 500 ppm (parts-per-million) with a concomitant increase in the Earth's surface temperature of 2 °C or more with respect to the pre-industrial conditions. (Other sufficient conditions, for example, the wholesale destruction of marine ecosystems, would fulfill this definition as well, but I am not concerned with those subjects today.)

Let us now go through the logic of Rethinking Wedges. I have left out a lot of unnecessary detail which is available in the paper itself.

1.  The authors assume the IPCC's (SRES) A2 marker scenario, which is a high-growth/high-emissions scenario going forward in the 21st century (but not nearly the highest). Why did they choose A2?

In the first half of this century, the A2 scenario is near the center of the plume of variation of the SRES emissions scenarios. Indeed, actual annual emissions have exceeded A2 projections for more than a decade. During this period, strong growth of global emissions has been driven by the rapid, carbon-intensive growth of emerging economies, which has continued despite the global financial crisis of 2008–9. For these reasons we believe that, among the SRES scenarios, A2 represents a reasonable 'business-as-usual' scenario. [See the figure below].

2.  The authors ran the HadCM3L climate model (from the Hadley Center of the UK Met Office) in combination with the A2 scenario, which demonstrated that Pacala and Sololow's original seven wedges are no longer adequate to avoid the fucked target.

Outcomes under A2 and with 9 stabilization wedges. Not even 9 wedges will do the trick with respect to CO₂ in the atmosphere (ppm, left frame), but the temperature increase comes in below 2 °C (right frame, blue line). But also note the orange and blue vertical bars showing the standard 2-sigma margin of error. It is possible we would see a 2 °C warming even if we implement 9 stabilization wedges.

3.  The authors conclude that CO₂ emission must peak and decline within the next 20 years. Emissions must be reduced to zero by 2060 (second graph below).

4. To accomplish the required peak and decline, and the subsequent phase-out, the authors conclude that we must implement 19 wedges, not 7 as Pacala and Sololow originally thought in 2004.

Given the current emissions trajectory, eliminating emissions over 50 years would require 19 wedges: 9 to stabilize emissions and an additional 10 to completely phase-out emissions. And if historical, background rates of decarbonization falter, 12 'hidden' wedges will also be necessary, bringing the total to a staggering 31 wedges.

The original 7 wedges can not stabilize the amount of CO₂ in the atmosphere at or  below the desired target (500 ppm) because total emissions have increased at a rapid rate over the last decade, mainly due to rapid industrialization in the "emerging" economies, particularly China.

5.  The authors conclude that current technologies and systems can not provide the amounts of carbon-free energy required to support the A2 growth scenario.

Filling this many wedges while sustaining global economic growth would mean deploying tens of terawatts of carbon-free energy in the next few decades.

Doing so would entail a fundamental and disruptive overhaul of the global energy system, as the global energy infrastructure is replaced with new infrastructure that provides equivalent amounts of energy but does not emit CO₂.

Current technologies and systems cannot provide the amounts of carbon-free energy needed soon enough or affordably enough to achieve this transformation.

An integrated and aggressive set of policies and programs is urgently needed to support energy technology innovation across all stages of research, development, demonstration, and commercialization. No matter the number required, wedges can still simplify and quantify the challenge.

And that concludes our summary of Rethinking Climate Wedges.

Commentary

The first thing we are struck by is that the authors urge the adoption of an "integrated and aggressive set of policies" starting now while making two crucial assumptions: 1) current energy technology will not cut the mustard; and 2) the world will likely follow the A2 economic growth/CO₂ emissions scenario. But if these assumptions are valid, there is no hope whatsoever that tens of terrawatts of carbon-free energy can be deployed in the next 2 decades. Not a snowball's chance in Hell. That is the painful lesson of recent experience since Pacala and Socolow's 2004 paper. Therefore, under these assumptions, we are entitled to conclude that humanity is fucked, in the sense defined above.

Despite this unhappy and unavoidable conclusion, the proposed solution urges humanity to do more of the same thing which has obviously not worked up to now (deployment of alternative energy sources, more technological innovation in energy systems). Thus the thinking of these scientists is constricted in a way that demands explanation. There is only one plausible path to salvation, which the authors never consider—the A2 economic growth scenario must be sacrificed if humanity is to avoid being fucked. And at this late date, halting and reversing humanity's energy demands may not solve the climate problem either.

Otherwise, humanity is Waiting For The Miracle.

To be fair, the authors may indeed have thought about the problems accompanying endless growth. There are two broad possibilities.

1.  These scientists are indeed aware that pursuing the A2 growth scenario (or something like it) is the fundamental problem. In this case, there are 3 possibilities—

• The authors don't think it is appropriate for them to suggest that economic growth must be restrained.
• The authors don't think anyone would take them seriously if they made such a suggestion.
• The authors think it simply doesn't matter what they think about economic growth because the issue is out of their hands.

2. These scientists are blissfully unaware that striving for endless economic growth on a finite planet is the fundamental problem, and impossible to boot.

There is no way to know what's going on in the authors' heads, but I strongly suspect that possibility #2 (cluelessness) reflects their thinking on the subjects of growth, climate and energy. Perhaps we should ask them.

In order, the authors of Rethinking Wedges are—

Steven Davis, lead author, Department of Earth System Science, University of California, Irvine, Irvine, CA 92697, USA.  E-mail: sjdavis@uci.edu

Long Cao, Department of Earth Sciences, Zhejiang University, Hangzhou, Zhejiang Province, 310027, People's Republic of China. E-mail: longcao@zju.edu.cn

Ken Caldeira, Department of Global Ecology, Carnegie Institution of Washington, Stanford, CA 94305, USA. E-mail: kcaldeira@carnegie.stanford.edu

Martin I. Hoffert, Department of Physics, New York University, New York, NY 10003, USA. E-mail: marty.hoffert@nyu.edu

Bear in mind that the issue on table is whether humanity is fucked or not.

You can ask them if you like, and direct them to this post. I have better things to do.

 

Comments

[John D]

It's amazing how many people think we can have limitless growth as soon as we get to 'clean energy'. I am convinced that if we found a way to produce free clean energy tomorrow we would still find a way to extinct ourselves. We would cut down every forest we could find and build McMansions and shopping malls. The world's population would grow until we were sitting on top of each other. And of course we could go to war with limitless firepower.

In the end, it all comes down to the false paradigm of infinite growth. Even smart scientists don't want to go against this religion.

[Andrew Kirk]

Reading this, I hear the "Lamentations of Jeremiah," by Thomas Tallis. Bleak and abject. It may not qualify for a "Remedy du Jour." But give it a listen anyhoo, and possibly hear your message in another medium.

[Ken Barrows]

Infinite growth is possible! Just make sure Chase and Goldman Sachs keep raking in massive profits. What's that? Never mind.

[Jim]

The very frustrating part is that it's considered crazy to suggest we shouldn't continue economic and population growth, when in reality it's the opposite approach that is the crazy part.

Honestly, I look at the above charts and think they're still being significantly over-conservative in their 'business as usual' projections. The world's economy is currently doubling about every 15 years. If it dropped to 3% growth per year, it would still double every 23 years. World energy consumption doesn't grow as fast, but it's still exponentional - it's roughly doubled from 1980 to now (but it should jump much higher with the massive growth in China, India, and other developing countries). World CO2 emissions are doubling every 20-30 years, but it's set for a massive jump with the growth in China and India.

The A2 growth scenario above projects roughly a doubling time in growth/emissions (A2) of 50-60 years. It doesn't track.

I get the strong, strong feeling that population, resource consumption, and emissions projections are often to always biased to not appear as bad as they really are. Somehow, a slowing of growth is always factored in - they never pretty much track the historical doubling times (or choose to look at the growth as linear instead of exponential).

[John D. Wheeler]

1d. The scientists know that if they suggest a no-growth solution they will not be able to receive any more funding.

I think Jim's comments point to the likelihood that they are not clueless. If they were truly clueless they probably would have made projections using historical figures. A doubling time of 72 years is a 1% growth rate, so a doubling time of 50-60 years is about as close to no growth as would be acceptable to the Powers That Be.

[Dave Cohen]

Well, Mr. Wheeler,

Your option #1(d) is certainly a possibility, but I'm sticking with #2.

It is natural of course that their views of economic growth would be conventional and thus self-serving (albeit unconsciously). Which leads us back to #2.

-- Dave

[Oliver]

What hurts the most is not that we are fucked, but that we are fucked without any concomitant pleasure, as should be the case with this marvellous old Germanic verb.

It's a bit like slipping between the sheets in the dark, snuggling up to a warm body and then realising grannie got into the wrong bed tonight.

[Mike Roberts]

Yes, I think that the notion of economic growth is now so ingrained that almost no-one can envisage a world without it. Political candidates who provide the most convincing argument to getting economic growth going will be the ones to get ahead of others. The possibility of no growth is almost never heard or read in conversations or media.

But, even with the ingrained notion of growth, it's still hard for me not to be continually surprised (an oxymoron?) that scientists, who I tend to believe can think critically, just take it for granted that constant economic growth is both possible and desirable.

[Bill Roope]

To put it simply; It is necessary to shut down industrial civilization immediately to avoid climate destabilization which
will destroy industrial civilization along with its enabler　humanity. But, shutting down industrial civilization suddenly would destroy most of humanity. It’s pretty predicament indeed.

[Makati1]

Dave, why does their avoiding the truth have to be "unconscious". These are supposedly intelligent people who certainly know who signs their paycheck. How many would be willing to lose their income and professional standing by putting out a real report and telling the Western world that they have to abandon 'for profit' capitalism and drastically cut their use of the world's natural resources? Maybe one in a thousand? And if their reports are 'peer reviewed' before publishing, how many tried and were shot down with the threat of being sidelined in their profession? And even if one report got through, how can it outweigh the thousands that do not report the real truth and are funded by powerful corporations? Just asking...

[Alexander Ač]

Hi all,

I send an e-mail to all authors, with a link to Dave's article, if they respond, I will let you know,

Alex

[Paleobotanist]

The mood at the AGU fall meeting was pretty bleak this year. I've heard Ken Caldeira speak, and I'd say the answer is "The authors don't think anyone would take them seriously if they made such a suggestion." Any climate/environmental scientist who dabbles in policy making knows that you just can't say it. Nobody wants to hear us say that.

Dave - I really enjoy your blog and drop by regularly, thank for it.

[Julian Bond]

I've been waiting for the axe to fall ever since reading "The Limits To Growth" back in the mid 70s. I still don't feel like I know if it's going to fall on my kids or their grand-kids. The message from that book and subsequent updates is simple. If the resource limits don't get you, the pollution will.

But what if the overshoot and instability is 30 years out? Do I care, since I probably won't see it? And my kids have a reasonable chance of making enough wealth in the mean time for personal soft landings. Or is that too cynical?