Deep Decarbonization: Truly facing the climate challenge


NASA EarthThe recently released Deep Decarbonization report shows that current government emission reductions commitments fall far short of what is needed to keep the world from warming more than 2 C degrees from preindustrial times. Few countries have analyzed the implications of such reductions for their economies, and few politicians have fully understood those implications. The US, for example, has an “all of the above” approach to energy development that is inconsistent with climate stabilization and that reflects the political class’s unwillingness to grapple with the implications of the 2 C warming limit. The report uses a methodology that is consistent with the strategy of “working forward toward a goal” by assessing the cost effectiveness of different paths for meeting a normatively-determined target. 

The following is a guest post. We believe that Koomey’s framing of the problem makes an essential contribution to climate policy advocacy.

Deep Decarbonization: Truly facing the climate challenge

Jonathan Koomey, Ph.D.

Research Fellow, Steyer-Taylor Center for Energy Policy and Finance, Stanford University

July 22, 2014

On July 8, 2014, an International group of experts presented the United Nations with an interim report on “Deep Decarbonization” [1]. This study is important because it takes seriously the commitment to keep the Earth’s temperature from rising more than 2 Celsius degrees from preindustrial times, a goal that the world’s major countries accepted in 2009 in Copenhagen. It then carries through an analysis of the technical potential for radically reducing emissions by 2050 in 15 major countries necessary to stay under that warming limit.

What the Deep Carbonization report finds should not be surprising to serious students of the climate problem [2], and it’s consonant with what leading analysts have known about this issue since the late 1980s [3]. The report concludes that

  • Allowing business-as-usual emissions trends to continue endangers the future orderly development of human civilization in the 21st century.
  • Achieving a low emissions world and fostering sustainable development go hand in hand.
  • Meeting the 2 C degree warming limit will require drastic reductions in greenhouse gas emissions in the next few decades, but few countries have analyzed the implications of such reductions for their economies, and few politicians have fully understood those implications.
  • Capturing substantial emissions reductions is possible using existing technologies, but achieving climate stabilization will require new technologies to be developed and deployed.
  • Solving the climate problem requires international commitments, because any one of the major emitting countries or regions could by themselves emit enough to make climate stabilization impossible.
  • Country by country analysis is an essential complement to global analyses of emissions reductions, because they yield technical and policy insights, but also because they foster a strategic conversation [4] among affected countries, groups, and citizens about how to achieve the needed emissions reductions.

As we’ve known for decades, we have “on the shelf” existing technologies that can achieve substantial reductions in GHG emissions [5, 6]. The issue is that society has not yet come to grips with what the 2 C limit implies: a World War II level commitment to emissions reductions over the next few decades. Current policies are simply not adequate to meet the challenge.

The US, for example, has an “all of the above” energy strategy that is inconsistent with climate stabilization and that reflects the political class’s unwillingness to grapple with the implications of the 2 C warming limit. To meet that commitment, we’ll need to favor low and zero emissions technologies over fossil fuels, which means (or should mean) no more leasing of coal, oil, or natural gas on public lands, no more fossil fuel export terminals, no more pipelines to high emissions petroleum supplies, no more government loans or subsidies for fossil fuel infrastructure, and a winding down of large scale investments in high emissions fuels of all sorts, both here and abroad. The emissions controls in the recently proposed EPA power plant regulations (among others) will be helpful in that regard, but more efforts are needed to improve efficiency across the board, keep fossil fuels in the ground, decarbonize the electricity sector, promote non-fossil energy sources, reduce methane leaks, stop and reverse deforestation, and move personal vehicles toward electricity to reduce oil use.

coldcashthumbI demonstrate in Cold Cash, Cool Climate [2] that we can’t meet the constraints of the 2 C warming limit without retiring some existing high emissions capital early, which implies that the more we build now the more we’ll have to shut down later. It’s easier to stop a power plant from being built than to shut it down after it’s operating (and generating profits). As Amory Lovins says, “If you can’t afford to build it right the first time, how come you can afford to build it twice?”

We’ll also need to keep a significant fraction (more than two thirds) of all fossil fuel reserves in the ground if we’re to meet the 2 C warming limit [2, 7]. President Obama understands this reality, which shows that science advisor John Holdren has been educating him: in his recent interview with Tom Friedman the President said “We’re not going to be able to burn it all.” That makes the “all of the above” energy strategy all the more puzzling, since installing more fossil fuel infrastructure implies that we will indeed “burn it all” (and more).

The report adopts what they call a “backcasting” methodology, which is a term equivalent to but not as evocative as what I call “working forward toward a goal” (I used the term “working backwards” before John Harte at the Energy and Resources Group suggested in 2011 that I needed a better term). Here’s what I wrote about that approach in a recent article in the peer-reviewed journal Environmental Research Letters [8]:

This new way of thinking, which I call “working forward toward a goal”, involves assessing the cost effectiveness of different paths for meeting a normatively-determined target. It has its origins in the realization that stabilizing the climate at a certain temperature (e.g., a warming limit of 2 Celsius degrees above pre-industrial times) implies a particular emissions budget, which represents the total cumulative greenhouse gas emissions compatible with that temperature goal.

This approach had its first fully-developed incarnation in 1989 in Krause et al. [3] (which was subsequently republished in 1992 [9]). It was developed further in Caldiera et al. [10] and Meinshausen et al. [7], and has recently served as the basis for the International Energy Agency’s analysis of climate options for several years running [11, 12, 13].

Such an approach has many advantages. It encapsulates our knowledge from the latest climate models on how cumulative emissions affect global temperatures, placing the focus squarely on how to stabilize those temperatures. It places the most important value judgment up-front, embodied in the normatively determined warming limit, instead of burying key value judgments in economic model parameters or in ostensibly scientifically chosen concepts such as the discount rate. It gives clear guidance for the rate of emissions reductions required to meet the chosen warming limit, thus allowing us to determine if we’re “on track” for meeting the ultimate goal, and allowing us to adjust course if we’re not hitting those near-term targets.   It also allows us to estimate the costs of delaying action or excluding certain mitigation options, and provides an analytical basis for discussions about equitably allocating the emissions budget. Finally, instead of pretending that we can calculate an “optimal” technology path based on guesses at mitigation and damage cost curves decades hence, it relegates economic analysis to the important but less grandiose role of comparing the cost effectiveness of currently available options for meeting near-term emissions goals.

“Working forward toward a goal” is a more business-oriented framing of the climate problem [2]. It mirrors the way companies face big strategic challenges, because they know that accurately forecasting the future of economic and social systems is impossible [14, 15], so they set a goal and figure out what they’d have to do to meet it, then adjust course as developments dictate. To do so, they implement many different options, evaluate continuously, and do more of what works and less of what doesn’t.   Such an approach, which the National Research Council [16] dubs “iterative risk management”, recognizes the limitations of economic models and frees us from the mostly self-imposed conceptual constraints that make it hard to envision a future much different from the world as it exists today [2].

Other recent analyses that adopt a similar approach for the US and for California, respectively, are Lovins et al. [17] and Williams et al. [18] In both of these studies, and in all previous ones conducted by competent analysts, decarbonization of the electricity sector plays a key role, because the potential for reductions there is larger than in other sectors and lower emissions electricity can then substitute for fuel use in buildings, industry, and transportation. They also acknowledge the criticality of path dependence. Our choices now affect our options later, a fact often ignored in conventional economic analyses of the climate problem.

The Deep Carbonization report shows that current government emission reductions commitments fall far short of what is needed to keep the world from warming more than 2 C degrees from preindustrial times. Substantial emissions reductions are possible with existing technologies, but we’ll need new technologies in coming decades to keep those reductions coming at the pace we need. That means R&D is critical, but only as a supporting component of a broad based deployment strategy that achieves cost reductions through learning by doing [19]. More importantly, policy makers need to confront the reality that current efforts are nowhere near adequate for the challenge we face. This new report represents good progress in that effort, and I look forward to seeing the final report in 2015.


1.  SDSN, and IDDRI. 2014. Pathways to Deep Decarbonization: Interim 2014 Report. Paris, France: Sustainable Development Solutions Network and Institute for Sustainable Development and International Relations. July 8. []
2.  Koomey, Jonathan G. 2012. Cold Cash, Cool Climate: Science-Based Advice for Ecological Entrepreneurs. Burlingame, CA: Analytics Press. []
3.  Krause, Florentin, Wilfred Bach, and Jon Koomey. 1989. From Warming Fate to Warming Limit: Benchmarks to a Global Climate Convention. El Cerrito, CA: International Project for Sustainable Energy Paths. []
4.  Ertel, Chris, and Lisa Kay Solomon. 2014. Moments of Impact: How to Design Strategic Conversations that Accelerate Change. New York, NY: Simon & Schuster. []
5.  Brown, Marilyn A., Mark D. Levine, Joseph P. Romm, Arthur H. Rosenfeld, and Jonathan G. Koomey. 1998. “Engineering-Economic Studies of Energy Technologies to Reduce Greenhouse Gas Emissions: Opportunities and Challenges.” In Annual Review of Energy and the Environment 1998. Edited by J. M. Hollander. Palo Alto, CA: Annual Reviews, Inc.
6.  Brown, Marilyn A., Mark D. Levine, Walter Short, and Jonathan G. Koomey. 2001. “Scenarios for a Clean Energy Future.” Energy Policy (Also LBNL-48031). vol. 29, no. 14. November. pp. 1179-1196.
7.  Meinshausen, Malte, Nicolai Meinshausen, William Hare, Sarah C. B. Raper, Katja Frieler, Reto Knutti, David J. Frame, and Myles R. Allen. 2009. “Greenhouse-gas emission targets for limiting global warming to 2 degrees C.” Nature. vol. 458, April 30. pp. 1158-1162. []
8.  Koomey, Jonathan. 2013. “Moving Beyond Benefit-Cost Analysis of Climate Change.” Environmental Research Letters. vol. 8, no. 041005. December 2. []
9.  Krause, Florentin, Wilfred Bach, and Jonathan G. Koomey. 1992. Energy Policy in the Greenhouse. NY, NY: John Wiley and Sons.
10.  Caldeira, Ken, Atul K. Jain, and Martin I. Hoffert. 2003. “Climate Sensitivity Uncertainty and the Need for Energy Without CO2 Emission ” Science. vol. 299, no. 5615. pp. 2052-2054. []
11. IEA. 2010. World Energy Outlook 2010. Paris, France: International Energy Agency, Organization for Economic Cooperation and Development (OECD). November 9. []
12.  IEA. 2011. World Energy Outlook 2011. Paris, France: International Energy Agency, Organization for Economic Cooperation and Development (OECD). November 9. []
13.  IEA. 2012. World Energy Outlook 2012. Paris, France: International Energy Agency, Organization for Economic Cooperation and Development (OECD). November 12. []
14.  Scher, Irene, and Jonathan G. Koomey. 2011. “Is Accurate Forecasting of Economic Systems Possible?” Climatic Change. vol. 104, no. 3-4. February. pp. 473-479. []
15.  Koomey, Jonathan G., Paul Craig, Ashok Gadgil, and David Lorenzetti. 2003. “Improving long-range energy modeling: A plea for historical retrospectives.” The Energy Journal (also LBNL-52448). vol. 24, no. 4. October. pp. 75-92. []
16.  NRC. 2011. America’s Climate Choices. Washington, DC: National Research Council of the National Academies. The National Academies Press. []
17.  Lovins, Amory B., Mathias Bell, Lionel Bony, Albert Chan, Stephen Doig, Nathan J. Glasgow, Lena Hansen, Virginia Lacy, Eric Maurer, Jesse Morris, James Newcomb, Greg Rucks, and Caroline Traube. 2011. Reinventing Fire: Bold Business Solutions for the New Energy Era. White River Junction, VT: Chelsea Green Publishing. []
18.  Williams, James H., Andrew DeBenedictis, Rebecca Ghanadan, Amber Mahone, Jack Moore, William R. Morrow, Snuller Price, and Margaret S. Torn. 2012. “The Technology Path to Deep Greenhouse Gas Emissions Cuts by 2050: The Pivotal Role of Electricity.” Science. vol. 335, no. 6064. January 6, 2012. pp. 53-59. []
19.  O’Neill, Brian C., Paul Crutzen, Arnulf Grübler, Minh Ha Duong, Klaus Keller, Charles Kolstad, Jonathan Koomey, Andreas Lange, Michael Obersteiner, Michael Oppenheimer, William Pepper, Warren Sanderson, Michael Schlesinger, Nicolas Treich, Alistair Ulph, Mort Webster, and Chris Wilson. 2006. “Commentary: Learning and Climate Change.” Climate Policy. vol. 6, no. 5. pp. 585-589.

Earlier posts:

Koomey: Moving beyond benefit-cost analysis of climate change

Koomey: Clean energy: Learning by doing only happens if we DO!

Book review: Cold Cash, Cool Climate

Jon Koomey on climate change mitigation, corporate power, social responsibility, and the role of the market

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2 Responses to Deep Decarbonization: Truly facing the climate challenge

  1. Lawrence N. Allen says:

    Unfortunately, stabilizing at 2 degrees Celsius above preindustrial times, corresponding to about 350 parts per million of carbon dioxide will cause all of the ice to melt. The ice sheets were in retreat at 280 parts per million during the interglacials. What happened then was that the melting ran out of time. Driven by cycles in solar irradiance and wobbles in the earth’s orbit, the warming cycle was necessarily followed by a cooling cycle. Such is not the case today. It would be interesting to know what carbon dioxide level would get the ice to come back. I would guess somewhere near 230 parts per million. A realistic fix on what might actually be required will enable us to calculate the amount of excess carbon that needs to be mined from the atmosphere and the oceans.

    • Yes, there’s a strong case to be made for a lower warming limit, but we don’t yet know how fast we’ll be able to reduce emissions in practice. I’m convinced that we can move much faster than most people think, but practical constraints may arise that we can’t now anticipate. Once we really start down the path towards meeting the 2 C limit we can decide if faster action is possible, but until we make that initial serious effort, arguing for a lower warming limit is purely an academic exercise. Let’s get going towards the 2 C limit and THEN have the argument about whether we should be moving faster. I agree that we need to move as fast as we can. We’ve squandered the last two decades and now a World War II scale effort is what is required.

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