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The role of synthetic biology in atmospheric greenhouse gas reduction: Prospects and challenges

Abstract: The long atmospheric residence time of CO2 creates an urgent need to add atmospheric carbon drawdown to CO2 regulatory strategies. Synthetic and systems biology (SSB), which enables manipulation of cellular phenotypes, offers a powerful approach to amplifying and adding new possibilities to current land management practices aimed at reducing atmospheric carbon. The participants (in attendance: Christina Agapakis, George Annas, Adam Arkin, George Church, Robert Cook-Deegan, Charles DeLisi, Dan Drell, Sheldon Glashow, Steve Hamburg, Henry Jacoby, Henry Kelly, Mark Kon, Todd Kuiken, Mary Lidstrom, Mike MacCracken, June Medford, Jerry Melillo, Ron Milo, Pilar Ossorio, Ari Patrinos, Keith Paustian, Kristala Jones Prather, Kent Redford, David Resnik, John Reilly, Richard J. Roberts, Daniel Segre, Susan Solomon, Elizabeth Strychalski, Chris Voigt, Dominic Woolf, Stan Wullschleger, and Xiaohan Yang) identified a range of possibilities by which SSB might help reduce greenhouse gas concentrations and which might also contribute to environmental sustainability and adaptation. These include, among other possibilities, engineering plants to convert CO2 produced by respiration into a stable carbonate, designing plants with an increased root-to-shoot ratio, and creating plants with the ability to self-fertilize. A number of serious ecological and societal challenges must, however, be confronted and resolved before any such application can be fully assessed, realized, and deployed.

Global CO2 impacts of light-duty electric vehicles

Summary: The electrification of private cars and light trucks—the vast majority of which are now powered by internal combustion engines (ICEs)—will be critical to efforts to keep global warming well below 2°C or 1.5°C, the long-term goals of the Paris Agreement. Replacing today’s fleet of gasoline and diesel ICEs with plug-in hybrid (PHEV) and battery (BEV) electric vehicles (EVs) could practically eliminate emissions from these light-duty vehicles as part of a broader strategy to decarbonize the transportation sector.

To better understand the potential impact of electric vehicle deployment on total global carbon dioxide emissions, MIT Joint Program researchers enhanced the MIT Economic Projection and Policy Analysis (EPPA) model to represent the fleet dynamics of light-duty vehicles (LDVs) including ICEs, PHEVs and BEVs. Using the enhanced model, they projected global and regional LDV emissions under different climate policy scenarios between the years 2015 and 2050.

The study considered a range of increasingly stringent policy scenarios, from a reference scenario that excludes national pledges delineated in the Paris Agreement to one aligned with the accord’s long-term 2°C goal. The researchers found that as the number of global LDVs grows from 1.1 billion to 1.6-1.8 billion between 2015 and 2050, EV units increase from 1 million to 585-825 million, and thus account for one-third (reference scenario) to one-half (2°C scenario) of the global LDV fleet. Even as the global LDV fleet grows by about 50 percent over the study period, total fleet CO2 emissions decline by about 50 percent under the 2°C scenario (compared to 10 percent in the reference scenario).

The study suggests that the electrification of light-duty vehicles could play an important role in broader efforts to mitigate global climate change, and highlights the caliber of insights that can be gained from including more precise representation of electric vehicle fleet dynamics in economy-wide energy-economic models.

Scenarios for the deployment of carbon capture and storage in the power sector in a portfolio of mitigation options

Summary: Aiming to avoid the worst effects of climate change, from severe droughts to extreme coastal flooding, the nearly 200 nations that signed the Paris Agreement set a long-term goal of keeping global warming well below two degrees Celsius. Achieving that goal will require dramatic reductions in greenhouse gas emissions, primarily through a global transition to low-carbon energy technologies. In the power sector, these include solar, wind, biomass, nuclear and carbon capture and storage (CCS). According to more than half of the models cited in the Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report, CCS will be required to realize the Paris goal, but to what extent will it need to be deployed to ensure that outcome?

A new study in Climate Change Economics led by the MIT Joint Program on the Science and Policy of Global Change projects the likely role of CCS in the power sector in a portfolio of low-carbon technologies. Using the Joint Program’s multi-region, multi-sector energy-economic modeling framework to quantify the economic and technological competition among low-carbon technologies as well as the impact of technology transfers between countries, the study assessed the potential of CCS and its competitors in mitigating carbon emissions in the power sector under a policy scenario aligned with the 2°C Paris goal.

The researchers found that under this scenario and the model’s baseline estimates of technology costs and performance, CCS will likely be incorporated in nearly 40 percent of global electricity production by 2100—one third in coal-fired power plants, and two-thirds in those run on natural gas. The study also found that the extent of CCS deployment, especially coal CCS, depends on the assumed fraction of carbon captured in CCS power plants. Ultimately, the authors determined that the power sector will continue to rely on a mix of technological options, and the conditions that favor a particular mix of technologies differ by region.

The changing nature of hydroclimatic risks across South Africa

Abstract: In this study, we present results from a large ensemble of projected changes in seasonal precipitation and near-surface air temperature changes for the nation of South Africa.

The ensemble is based on a combination of pattern-change responses derived from the Coupled Model Intercomparison Project Phase 5 (CMIP-5) climate models along with the Massachusetts Institute of Technology Integrated Global Systems Model (MIT-IGSM), an intermediate complexity earth-system model coupled to a global economic model that evaluates uncertainty in socio-economic growth, anthropogenic emissions, and global environmental response. Numerical experimentation with the MIT-IGSM considered four scenarios of future climate and socio-economic development to span a range of possible global actions to abate greenhouse gas emissions through the 21st century. We evaluate distributions of surface-air temperature and precipitation change over three regions across South Africa: western (WSoAfr), central (CSoAfr), and eastern (ESoAfr) South Africa.  

In all regions, by mid-century, we find a strong likelihood (greater than 50%) that temperatures will rise considerably higher than the current climate’s range of variability 
(a threefold increase over the current climate’s two-standard deviation range of variability). In addition, scenarios that consider more aggressive global climate targets (e.g. 2C and 15C scenarios) all but eliminate the risk of these acutely salient temperature increases. For precipitation, there is a preponderance of risk toward decreased precipitation (3 to 4 times higher than increased) for western and central parts of South Africa.

There is a clear benefit seen within the evolving hydroclimatic risks as a result of strong climate targets, such as limiting the global climate warming to 1.5˚C by 2100. We find that the risk of precipitation changes in the 15C scenario toward the end of this century (2065–2074) is nearly identical to that seen in the REF scenario during the 2030s. Thus, the climate risk that may be experienced in a decade as a result of current global actions to reduce emissions could be delayed by 30 years, and would provide invaluable lead-time for national efforts to be put in place to prepare, fortify, and/or adapt to these changing environments of risk.

Land-use change in the continental United States: Are there tipping points?

Abstract: Land use in the U.S. is driven by multiple forces operating at the global level such as income and population growth, yield and productivity improvement, trade policy, climate change, and changing diets. Future land use has implications for biodiversity, run-off, carbon storage, ecosystem values, agriculture and the broader economy. We investigate those forces in the U.S. and their implications from a multi-sector, multi-system dynamics (MSD) perspective focused on understanding dynamics and resilience in complex interdependent systems.

Historical trends show slightly increased grassland and natural forest areas and decreases in cropland. We project these trends will be intensified under higher pressures for agricultural land or reduced under lower pressures, with no evidence of tipping points toward larger agricultural land abandonment or deforestation. However, U.S. sectoral output and trade, fertilizer use, N2O and CH4 emissions from agriculture activities, and CO2 emissions from land-use change are substantially impacted under several land-use forcing scenarios.

The role of shale gas in shaping the U.S. long-run CO2 emissions

Abstract: The shale gas boom in the U.S. has lowered the U.S. CO2 emissions in recent years mainly through substitution of gas for coal in power generation. Will the shale gas boom reduce the emissions in the long-run as well?

To study this, we consider a counterfactual without the shale gas boom based on a general equilibrium modeling for the 2011 U.S. economy. To enhance the power sector modeling, the supply responses of coal-fired and gas-fired generations are calibrated to existing research. We find that if gas prices remain at 2007 levels in 2011, only a model setting that allows very little reduction in electricity demand, reflecting a short-run demand response, generates an increase in economy-wide emissions. For all other cases, the higher gas price under the counterfactual will have a dampening effect on economic activities and consequently lowers economy-wide emissions, even though the power sector emissions may increase due to the gas-to-coal switch.

In other words, without any policy intervention, although the shale gas boom could reduce emissions in the short run, it may lead to higher emissions in the long run if the low gas prices persist. Our finding suggests that extrapolating the current decline in emissions due to the shale gas boom to the distant future could be misleading. Instead, if curbing emissions is the goal, rather than depending upon the cheap gas, policies and measures for cutting emissions remain imperative.

Plausible Energy Futures: An MIT Energy Initiative Working Paper

Executive Summary: The global energy system is undergoing major transformations. The world faces a dual challenge of meeting increasing energy demand while reducing greenhouse gas emissions. This change is characterized by the convergence of power, transportation, industrial, and building sectors, and the surge of multi-sectoral integration. Such transformation of energy systems requires a combination of technology selection and policy choices to ensure providing reliable and clean energy. Understanding the implications of these dynamics is challenging and requires a holistic approach to provide systemslevel insights.

In this working paper, we provide an overview of energy transformation analysis and projection tools and discuss the use of quantitative methods to examine possible future energy pathways. This is done to facilitate achieving decarbonization goals by providing thought leaders and policy makers with a robust framework in which energy choices and decarbonization goals can be made based on lifecycle analyses. We synthetize our findings applicable to modeling tools based on discussions with colleagues in other academic institutions and government labs and provide a summary of a wide range of lifecycle assessment (LCA) and energy modeling tools.

Our assessment shows that although there is considerable related research work emerging, there is a lack of readily available or generally accepted quantitative models and tools that consider a broad and robust lifecycle analysis approach for a range of plausible energy futures at regional and national levels. Such a tool is needed to help policy makers, industry, investors, and the financial sector to better understand and make decisions on energy choices and energy transitions, and avoid narrowlyframed and advocacy-driven pathways.

We at MIT have substantial experience in building and maintaining energy system assessment tools:

i) A comprehensive system-level and pathway-level lifecycle assessment model, which is called the Sustainable Energy Systems Analysis Modeling Environment (SESAME). SESAME is a publicly available, open access model with multi-sector representation.

ii) The Integrated Global System Modeling framework (IGSM), which combines an economy-wide, multi-sector, multi-region computable general equilibrium (CGE) model (The MIT Economic Projection and Policy Analysis model, EPPA) with a natural systems component (The MIT Earth System model, MESM). The IGSM is an integrated assessment model (IAM).

To quantify additional environmental impact categories such as air pollutants and water footprint, we develop an expanded SESAME platform. For an economy-wide scenario analysis, we use the modeling results from our EPPA model. The expanded SESAME version will be a publicly available technology options and scenario analysis tool that can use input information from any economy-wide system (or use the default settings that represent our base-case values). The tool will evaluate options, impacts, and national energy choices for exploring the impacts of relevant technological, operational, temporal, and geospatial characteristics of the evolving energy system. It focuses on lifecycle analysis with high technology resolution (linked with the existing MIT energy-economic models) that provides economic information and quantifies lifecycle GHG emissions, as well as impacts related to criteria pollutants and water. Such analysis highlights how effective policy choices and technology selection can reduce such environmental impacts.

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