Carbon Mitigation Initiative

Policy & Integration Group

Policy & Integration Group
The objective of the Policy & Integration Program is to bring new thinking into policy formulation and to communicate the policy relevance of CMI research. The faculty members involved are Co- Directors Steve Pacala & Rob Socolow, Alex Glaser, Michael Oppenheimer, and M.V. Ramana.

This year the group has continued its efforts to assess the potential of mitigation strategies and educate policy-makers and the public, while seeking to “restart” the discussion on carbon mitigation strategies.


Assessing mitigation options

  • Continued efforts were made to engage various stakeholders (via meetings, presentations, and publications) in the debate over carbon dioxide removal from the atmosphere and to educate the public about such negative emissions strategies.
  • Findings from a project on small modular nuclear reactors indicates that the reactors would require enhanced safeguards and novel fuel-cycle architectures to avoid a higher proliferation risk than current gigawatt-scale reactors.

Communicating climate change risks

  • An article in the Vanderbilt Law Review urges the environmental community to “restart” the carbon and climate debate by communicating hard truths to the public and framing mitigation as a risk management issue.
  • Several CMI members have authored an open letter to President Obama urging quick action on climate change to move back the hands of the “Doomsday Clock.”
  • A new framework being is being developed to provide a global map of the local probability distribution of ice-sheet driven sea level rise.


  • The stabilization wedges concept continues to be widely used in courses and textbooks, and a new LEGO model is being developed as an educational tool for schoolchildren in the Midwest.
  • Work continues on enabling the development of open-source energy models, with a particular focus on a low-carbon growth strategy for India.
  • CMI has continued its close relationship with Climate Central, which may be strengthened by the group’s partnership in a proposed NSF Science & Technology Center to be led by Jorge Sarmiento of the Science Group.

Assessing Mitigation Options

Robert Socolow, Alexander Glaser, and M.V. Ramana have led efforts to assess the challenges and benefits of negative emissions strategies and new nuclear technologies.

Prospects for direct air capture of CO2

A major focus of Robert Socolow and colleagues in 2012 was bridging the gaps between various stakeholders in the debate over the mitigation potential of carbon dioxide removal (CDR) from the atmosphere. The previous year’s publication of an American Physical Society Report co-chaired by Socolow and BP’s Michael Desmond suggested that air capture costs would be ~$600/ton CO2, much higher than previously suggested by CDR proponents. In a paper written with report co-authors Marco Mazzotti and Renato Baciocchi, Socolow and Desmond this year updated the cost estimate using an optimized design, but costs were reduced by only 7%. In light of these findings, Socolow attended a meeting of major players in the field of air capture in March and emphasized that CDR will only make sense after the majority of large-scale CO2 sources have been decarbonized, and encouraged participants not to allow audiences to infer that humanity can “solve” climate change while being relaxed about fossil fuels.

Socolow and Massimo Tavoni were also instrumental in assembling a compendium of papers on CDR strategies that will be published as a special issue of Climatic Change edited by Michael Oppenheimer. The issue provides an original and self-contained assessment of the role of negative emissions by bringing together leaders of the integrated assessment community with experts on technology, natural science, and political science. Socolow and Tavoni wrote the introductory article for the issue, and worked with the journal to make it available to the public free of charge.

Re-engineering the nuclear future

Two years after the Fukushima accident, many countries around the world continue to consider an increasing role for nuclear power. An important component in future nuclear installations will likely be a new generation of small modular reactors (SMRs), with power outputs of 100 to 300 MWe, being developed in several countries. These reactors are expected to cost significantly less than current gigawatt-scale reactors and thereby address some of the economic challenges faced by utilities interested in constructing nuclear power plants.

The main focus during the past year of the Re-engineering the Nuclear Future project led by Alexander Glaser and M. V. Ramana has been to estimate resource requirements, waste generation, and proliferation risks associated with SMRs of different kinds relative to current light-water reactors. Their computer simulations show that SMRs based on light-water reactor technologies have a significantly higher uranium and enrichment demand, which could affect fuel-cycle choices in some countries. In contrast, SMRs with long-lived cores based on fast neutrons have substantially lower uranium and enrichment demand, and produce a smaller volume of waste relative to both conventional and small light water reactors. However, all SMRs examined so far produce substantially greater amounts of plutonium per MWh of electrical energy generated than conventional reactors.

Due to the larger amounts of plutonium generated, the results of a probabilistic model of proliferation applied to SMRs suggest that if a fleet of SMRs is deployed with the same efficiency of safeguards, it would have a somewhat increased proliferation risk compared to a fleet of gigawatt-scale reactors generating the same electric power. This finding highlights the importance of “safeguards-friendly” design choices for SMRs and, ideally, new fuel-cycle architectures to reduce these risks.

figure 22

Glaser and Ramana have been involved in analyzing several policy issues for SMR licensing critical to determining the economic viability of these reactors, including security requirements, insurance and liability arrangements, and the size of the emergency planning zone. In future work, they will be analyzing the concern that the promised safety enhancements in SMR designs could be “offset” by a simultaneous relaxation of licensing requirements, e.g., by siting SMRs closer to urban areas.

As part of the Re-engineering the Nuclear Future project, the researchers are also engaging students on research related to the project. Edward McClamrock (MAE, Class of 2013) is writing his Senior Thesis on Molten Salt Reactors and the potential of thorium fuel, which has been considered as an alternative to uranium because it is much more abundant. Similarly, as a recipient of a PEI/ STEP fellowship, David Turnbull (PhD candidate, MAE) examined the “option value” of fusion energy for low-carbon energy scenarios. We are collecting these results to make them available to a broader audience on our website dedicated to the Re-engineering the Nuclear Future project (http://

Wind catch-up in China

Working with Robert Socolow, Nicolas Lefevre has completed a Ph.D. thesis on technological “catch up” as illustrated by the rise of the Chinese wind turbine industry. Lefevre’s hypothesis is that firms in a developing country can develop the capability to compete at a global technological frontier previously dominated by industrialized country firms, provided the developing country enables its domestic firms to pursue coherent and long-term strategies and provided the frontier is not evolving especially rapidly. The thesis zeroes in on the windpower industry in China, where the catch-up process is nearly complete (Figure 23). Firm-level analysis for Chinese windpower developers reveals rapid passage from an initial period of learning from western firms to a period of strong government support for dramatic expansion into large domestic markets. At the same time, the wind power frontier was evolving relatively slowly due to limited early support from the governments of industrialized countries, which facilitated the process of technological catch-up by Chinese firms.

figure 23

Communicating Climate Risks

The Socolow and Oppenheimer groups are working to re-energize climate discussions by suggesting new strategies for climate communication and providing descriptions of climate risks relevant to policymakers.

Hard truths of managing climate change

In 2011, Robert Socolow authored an article entitled “Wedges Reaffirmed” that called for a shift in communication strategy by the environmental community to motivate action on carbon mitigation. This year, Socolow continued that theme in an article in the Vanderbilt Law Review entitled “Truths We Must Tell Ourselves to Manage Climate Change,” which encouraged environmentalists to find “restart buttons” for the climate dialogue by changing the conversation. Socolow advocates for communicating some hard truths to the public about carbon and climate by acknowledging that:

  • climate change is “unwelcome news” and that tackling the problem will require a huge effort by the planet’s citizens;
  • there is still considerable uncertainty in climate projections;
  • the risk of climate change must be balanced with the risk of disruption from mitigation; and
  • a 2°C target may not be attainable.

Socolow argues that the public is sophisticated enough to understand climate change problem as a risk management problem, and that is up to the environmental community to convey the magnitude of potential climate risks and make the case for global participation in the solution.

Bulletin letter to President Obama

CMI-associated faculty members Alexander Glaser, M.V. Ramana, and Robert Socolow serve on the Science and Security Board of the Bulletin of the Atomic Scientists. In January 2013, the Board authored an open letter to President Barack Obama regarding this year’s setting of the Bulletin’s “Doomsday Clock.” Originally conceived to highlight the dangers of nuclear weapons, the assessment now also encompasses “climate-changing technologies and new developments in the life sciences that could inflict irrevocable harm.”

After moving the hands of the clock back one minute following the first year of President Barack Obama’s presidency (to six minutes before midnight), the Society has since moved the hands forward one minute and this year they remain in that position. In addition to urging the President to mitigate nuclear risks, the authors urged President Obama to make climate change a high priority; specifically, to work to forge an international response to climate change, ensure natural gas is exploited in an environmentally safe manner, promote carbon capture and storage, and clear barriers to renewables expansion.

Socolow, Chair of the Science and Security Board, noted, “We have as much hope for Obama’s second term in office as we did in 2010, when we moved back the hand of the Clock after his first year in office. This is the year for U.S. leadership in slowing climate change and setting a path toward a world without nuclear weapons.”

Assessing risk from sea level rise

Current continental-scale models of the Greenland and Antarctic ice sheets do not adequately represent the physical processes underlying rapid, climate-driven dynamic ice loss, and are thus insufficient to project the ice sheet contribution to sea level rise. To improve predictions of future sea- level change, Chris Little and Michael Oppenheimer have focused on improving ice sheet models and developing sea level projections that are more conducive to a risk management approach.

To this end, the researchers have developed a “bottom-up” approach to projecting sea level change. Applying a Bayesian probabilistic framework to the Antarctic ice sheet (Figure 24), they have transformed disparate sources of information constraining future ice sheet behavior into probability distributions. This novel methodology allows a consistent comparison with other projection techniques and also resolves the quantitative impact of key physical uncertainties, clarifying observational and numerical modeling research priorities.

This year, the group will extend this framework to include: 1) changes in the Greenland ice sheet mass balance; 2) the solid earth and gravitational response that modulate sea level changes at the local level; and 3) new constraints from process-based ice sheet models, smaller-scale observations of ice loss, paleo-sea-level observations, and expert judgment. These extensions will allow the development of a global map of the local probability distribution of ice-sheet driven sea level rise, facilitating the assessment of sea-level rise alongside other climate-related risks.

figure 24

Policy-Relevant Tools for Education and Research

In 2012 CMI continued its commitment to providing the public with tools for understanding climate change and options for reduction of carbon emissions.

Stabilization Wedges

The stabilization wedges concept for cutting carbon emissions remains a popular tool in the environmental and education communities. Roberta Hotinski continues to field dozens of questions from educators at all levels interested in using the wedges game in their courses, and wedges graphics appeared in 7 textbooks in 2012, as well as in Sierra Magazine and the Orange County Register.

In one of the most innovative applications of the wedges we’ve heard of, Brian Alano, an engineer and member of the Indiana group Greenfield LEGO User Education, is constructing a time-dynamic interactive simulation of the wedges concept out of LEGO elements. The goal is to simulate emissions as a flow rate of LEGO soccer balls, and to allow participants to select mitigation policies each year which reduce or direct emissions away from the atmosphere. With feedback from Hotinski, Alano has created an Excel model of carbon flows for the simulation and constructed modules for a coal power plant, a cloud (representing atmospheric CO2), and land and ocean carbon sinks that were displayed at Brickworld 2013 in Chicago.

Alano plans to finish the prototype by June this year, play-test it throughout the summer, and have a full-scale model complete by the end of the calendar year. In addition to showing the model as an interactive display at LEGO exhibitions, he plans to take the wedges simulation into schools to empower kids to act against rapid climate change and to encourage them to be engineers--a profession whose skills are vital to mitigating climate change and its effects.

Open-source energy-economics models

Another focus of the Policy & Integration Group has been the development of energy-economics models for use by the wider community. Shoibal Chakravarty has combined a number of various open source software tools to create a platform for fast and collaborative development of energy- economics models. The model is written in the open-source and popular programming language Python, using mathematical modeling software from the COOPR project (https://software.sandia. gov/trac/coopr). The models can be solved using solvers from COIN-OR ( project of the Operations Research community. Chakravarty and colleagues are developing a web- based user interface for interactive data input and graphical data output from the model runs. The goal is to make it easy to rapidly prototype, develop and collaborate on such topics across various computing platforms. A web based interface can be used on all computers - Windows, Linux or Mac. Publishing model runs and results on the web can also become automatic.

One short term goal of the project is to collaboratively develop an energy-economics model for a low carbon growth strategy for India. This will be developed in an open online collaboration with energy experts in India.

figure 25

Climate Central

CMI continues to have close ties with Climate Central, a non-profit organization in Princeton dedicated to providing the public and policy-makers with clear and objective information on climate change trends and impacts. Steve Pacala and Michael Oppenheimer serve on the board of Climate Central (CC), Eric Larson of the Low-Carbon Energy group works at CC part-time, and CMI researchers have both advised the group and served as topics of the organization’s stories. A new tie has also been forged between Princeton and CC over the last year as Heidi Cullen, CC’s Chief Climatologist, has worked with the CMI Science Group’s Jorge Sarmiento on the education and outreach component of a proposal for a Center for Southern Ocean Biogeochemical Observations and Modeling (see summary in the Carbon Science Group section, p. 14). A video produced for the proposal site visit is already gaining attention, raising the profile of the Southern Ocean’s role in climate and the carbon cycle and generating excitement over the robotic observing system proposed.

Policy & Integration Publications

Glaser, A., L. B. Hopkins and M. V. Ramana. “Resource Requirements and Proliferation Risks Associated with Small Modular Reactors.” Nuclear Technology. Forthcoming, 2013.

Little, C., M. Oppenheimer, N.M. Urban. “Upper bounds on 21st century Antarctic ice loss assessed using a probabilistic framework.” Nature Climate Change. In press. 2013.

Little, C., N.M. Urban, and M. Oppenheimer. “A probabilistic framework for assessing the ice sheet contribution to sea level change.” Proceedings of the National Academy of Sciences. In press. 2013.

Ramana, M. V., L. B. Hopkins and A. Glaser. “Licensing Small Modular Reactors.” Energy. To be submitted. 2013.

Sergienko, O. V., D.N. Goldberg, C. M. Little. “Alternative ice-shelf equilibria determined by ocean environment.” Journal of Geophysical Research-Earth Surface. In revision. 2013.

Socolow, R.H., “High-consequence outcomes and internal disagreements: tell us more, please.” Climatic Change, Springer. DOI: 10.1007/s10584-011-0187-5. August 9, 2011.

Socolow, R.H., “Truths We Must Tell Ourselves to Manage Climate Change.” Vanderbilt Law Review, Vol. 65, Number 6, pages 1455-1478. 2012.

Socolow, R.H. “40-year phase-out for conventional coal? If only!” Environmental Ressearch Letters, 7, 011009. 2012.

Socolow, R.H., T. Rosenbaum, L.J. Korb, L. Eden, A. Glaser, J. E. Hansen, S. Kartha, E.“Rocky” Kolb, L. M. Krauss, L. Lederman, R. Rajaraman, M. V. Ramana, R. Rosner, J. Sims, R.C. J. Somerville and E. J. Wilson. “An open letter to President Obama: The time on the Doomsday Clock is five minutes to midnight.” Published on the Bulletin of the Atomic Scientist website. January 14, 2013.

Tavoni, M., S. Chakravarty and R.H. Socolow. “Safe vs. Fair: A Formidable Trade-off in Tackling Climate Change.” Sustainability, Volume 4, Issue 2. 2012.


Principal funding support for the Carbon Mitigation Initiative has been provided by BP International Limited.

Carbon Mitigation Initiative Leadership and Administration

Stephen W. Pacala, co-director
Robert H. Socolow, co-director
Rajeshri D. Chokshi, technical support specialist Stacey T. Christian, business administration Anna Colasante, administrative assistant
Katharine B. Hackett, associate director, Princeton Environmental Institute
Axel Haenssen, technical support specialist
Igor Heifetz, webmaster
Roberta M. Hotinski, science communication consultant
Ildiko Kohles, faculty assistant
Shavonne L. Malone, administrative assistant
Pascale M. Poussart, former assistant director, energy initiatives
Holly P. Welles, manager, communications and outreach

Contributing Editors

Roberta M. Hotinski
Holly P. Welles

<< Previous  |  Table of Contents  |  

Last update: April 10 2013
BP Princeton Environmental Institute © 2018 The Trustees of Princeton University
CMI is sponsored by BP.