Authors:Jay Fuhrman, Haewon McJeon, Scott C. Doney, William Shobe, Andres F. Clarens Abstract: Climate change mitigation strategies informed by Integrated Assessment Models (IAMs) increasingly rely on major deployments of negative emissions technologies (NETs) to achieve global climate targets. Although NETs can strongly complement emissions mitigation efforts, this dependence on the presumed future ability to deploy NETs at scale raises questions about the structural elements of IAMs that are influencing our understanding of mitigation efforts. Model inter-comparison results underpinning the IPCC's special report on Global Warming of 1.5°C were used to explore the role that current assumptions are having on projections and the way in which emerging technologies, economic factors, innovation, and tradeoffs between negative emissions objectives and UN Sustainable Development Goals might have on future deployment of NETs. Current generation IAM scenarios widely assume we are capable of scaling up NETs over the coming 30 years to achieve negative emissions of the same order of magnitude as current global emissions (tens of gigatons of CO2/year) predominantly relying on highly land intensive NETs. While the technological potential of some of these approaches (e.g., direct air capture) is much greater than for the land-based technologies, these are seldom included in the scenarios. Alternative NETs (e.g., accelerated weathering) are generally excluded because of connections with industrial sectors or earth system processes that are not yet included in many models. In all cases, modeling results suggest that significant NET activity will be conducted in developing regions, raising concerns about tradeoffs with UN Sustainable Development Goals. These findings provide insight into how to improve treatment of NETs in IAMs to better inform international climate policy discussions. We emphasize the need to better understand relative strength and weaknesses of full suite of NETs that can help inform the decision making for policy makers and stakeholders. PubDate: 2019-12-04T00:00:00Z
Authors:Christoph Beuttler, Louise Charles, Jan Wurzbacher Abstract: In recent years Direct Air Capture (DAC) has established itself as a promising approach to atmospheric Carbon Dioxide Removal (CDR) also referred to as Negative Emissions. However, due to the amounts likely needed to be removed CDR technologies like DAC will only become climate relevant if they rapidly reach gigaton scale, around the middle of this century. Here we give a brief insight into DAC and in particular, the modular low temperature DAC technology developed by Climeworks of Switzerland. We discuss potential co benefits, in particular in relation to the Sustainable Development Goals (SDGs) of the United Nations and conclude by suggesting some policy approaches on how a climate relevant scale could be achieved in time. PubDate: 2019-11-21T00:00:00Z
Authors:Peter Kelemen, Sally M. Benson, Hélène Pilorgé, Peter Psarras, Jennifer Wilcox Abstract: Since the Industrial Revolution, anthropogenic carbon dioxide (CO2) emissions have grown exponentially, accumulating in the atmosphere and leading to global warming. According to the IPCC (IPCC Special Report, 2018), atmospheric warming should be PubDate: 2019-11-15T00:00:00Z
Authors:Keith Paustian, Eric Larson, Jeffrey Kent, Ernie Marx, Amy Swan Abstract: Soil carbon (C) sequestration is one of three main approaches to carbon dioxide removal and storage through management of terrestrial ecosystems. Soil C sequestration relies of the adoption of improved management practices that increase the amount of carbon stored as soil organic matter, primarily in cropland and grazing lands. These C sequestering practices act by increasing the rate of input of plant-derived residues to soils and/or by reducing the rates of turnover of organic C stocks already in the soil. In addition to carbon dioxide removal potential, increases in soil organic matter/soil C content are highly beneficial from the standpoint of soil health and soil fertility. Practices to increase soil C stocks include well-known, proven techniques, or “best management practices” (BMP) for building soil carbon. A second category includes what we refer to as frontier technologies for which significant technological and/or economic barriers exist today, but for which further R&D and/or economic incentives might offer the potential for greater sequestration over the longer term. We reviewed published estimates of global soil carbon sequestration potential, representing the biophysical potential for managed cropland and/or grassland systems to store additional carbon assuming widespread (near complete) adoption of BMPs. The majority of studies suggests that 4–5 GtCO2/y as an upper limit for global biophysical potential with near complete adoption of BMPs. In the longer-term, if frontier technologies are successfully deployed, the global estimate might grow to 8 GtCO2/y. There is a strong scientific basis for managing agricultural soils to act as a significant carbon (C) sink over the next several decades. A two-stage strategy, to first incentivize adoption of well-developed, conventional soil C sequestering practices, while investing in R&D on new frontier technologies that could come on-line in the next 2–3 decades, could maximize benefits. Implementation of such policies will require robust, scientifically-sound measurement, reporting, and verification (MRV) systems to track that policy goals are being met and that claimed increases in soil C stocks are real. PubDate: 2019-10-16T00:00:00Z
Authors:Lennart T. Bach, Sophie J. Gill, Rosalind E. M. Rickaby, Sarah Gore, Phil Renforth Abstract: Humankind will need to remove hundreds of gigatons of carbon dioxide (CO2) from the atmosphere by the end of the twenty-first century to keep global warming below 2°C within the constraints of the global carbon budget. However, so far it is unclear if and how this could be achieved. A widely recognized idea is to accelerate weathering reactions of minerals that consume CO2 when they dissolve. Acceleration could be realized by pulverizing and distributing gigatons of these minerals onto land (termed “enhanced weathering (EW)”) or sea (termed “ocean alkalinity enhancement (OAE)”) thereby largely increasing their reactive surfaces. However, the desired consumption of atmospheric CO2 during dissolution would inevitably be accompanied by a release of mineral dissolution products (alkalinity, Si, Ca, Mg, Fe, Ni, and maybe others). Here, we approximate their maximum additions to assess potential consequences for pelagic communities (mainly primary producers) and the biogeochemical fluxes they control. Based on this assessment, we tentatively qualify the potential to induce positive and/or negative side effects to be high for Fe, Ni, Si, intermediate for alkalinity, and low for Ca and Mg. However, perturbation potentials are always higher at perturbation hotspots and would be different for EW than for OAE. Furthermore, ecological/biogeochemical consequences of EW/OAE largely depend on the minerals used. We hypothesize that mainly calcifiers would profit in a scheme where CaCO3 derivatives would be used due to beneficial changes in carbonate chemistry. Figuratively, this may turn the blue ocean into a white(r) ocean. When using silicates, the release of additional Si, Fe and Ni could benefit silicifiers and N2-fixers (cyanobacteria) and increase ocean productivity ultimately turning the blue ocean into a green(er) ocean. These considerations call for dedicated research to assess risks and co-benefits of mineral dissolution products on marine and other environments. Indeed, both EW and OAE could become important tools to realize CO2 removal at the planetary scale but associated risks and/or co-benefits should be revealed before deciding on their implementation. PubDate: 2019-10-11T00:00:00Z
Authors:Mathilde Fajardy, Piera Patrizio, Habiba Ahut Daggash, Niall Mac Dowell Abstract: The large-scale removal of carbon dioxide from the atmosphere is likely to be important in maintaining temperature rise “well below” 2°C, and vital in achieving the most stringent 1.5°C target. Whilst various literature efforts have estimated the global potential of carbon dioxide removal (CDR) for a range of technologies with different degrees of certainty, regional bottlenecks for their deployment remain largely overlooked. Quantifying these barriers, through national and local case studies, rather than with aggregated approaches, would guide policy and research, as well as investments, toward regions that are likely to play a prominent role in CDR deployment. Five CDR technologies—including afforestation/reforestation, bioenergy with carbon capture and storage, biochar, direct air capture and enhanced weathering—are compared in this work. We discuss main technical, socio-economic and regulatory bottlenecks that have been scarcely investigated at regional level, and provide directions for further research. We identify the availability of accessible land, water, low carbon energy and CO2 storage as key regional drivers and bottlenecks to most CDR technologies. We discuss the caveats in CO2 accounting in assessing the performance of each technology, and the need for an international regulatory framework which captures these differences. Finally, we highlight the social, economic and political drivers which are central in unlocking the large scale deployment of CDR technologies, in a cost attractive, socially acceptable and politically achievable way. PubDate: 2019-10-01T00:00:00Z
Authors:Vanessa Núñez-López, Emily Moskal Abstract: This paper provides an overview of carbon dioxide enhanced oil recovery (CO2-EOR) and its ability to reduce greenhouse gas (GHG) emissions (even to the point of negative emissions), the role it needs to play in the challenge of decarbonization, and the need to scale up implementation and deployment in order to meet climate goals. Limitations in current legal and regulatory frameworks for CO2 injection are explored for both economic and environmental purposes, as well as the economic implications of combining CO2-EOR with geologic carbon storage. Results from a recent study, which demonstrate that all CO2-EOR operations produce negative emissions oil during the first several years of production, are analyzed in the context of the urgency of climate change mitigation. Acknowledging that fossil fuels currently provide the energy foundation upon which global societies function, and that a sudden shift in the composition of that foundation can potentially destabilize the global economy and key elements of modern society, we bring CO2-EOR to the fore as it can supply reduced carbon oil to support the current energy foundation as it steadily transitions toward decarbonization. In order to meet this urgent transition, greater fiscal, and regulatory incentives are needed to begin scaling CO2-EOR with storage around the globe. A viable and large-scale CO2-EOR/storage industry depends upon significant capital investments for CO2 capture and transportation infrastructure. Policy consistency and predictability, combined with targeted subsidies, will help to achieve this goal. PubDate: 2019-09-27T00:00:00Z
Authors:Duncan P. McLaren, David P. Tyfield, Rebecca Willis, Bronislaw Szerszynski, Nils O. Markusson Abstract: Targets and accounting for negative emissions should be explicitly set and managed separately from existing and future targets for emissions reduction. Failure to make such a separation has already hampered climate policy, exaggerating the expected future contribution of negative emissions in climate models, while also obscuring the extent and pace of the investment needed to deliver negative emissions. Separation would help minimize the negative impacts that promises and deployments of negative emissions could have on emissions reduction, arising from effects such as temporal trade-offs, excessive offsetting, and technological lock-in. Benefits for international, national, local, organizational, and sectoral planning would arise from greater clarity over the role and timing of negative emissions alongside accelerated emissions reduction. PubDate: 2019-08-21T00:00:00Z
Authors:S. Julio Friedmann Abstract: Over the past 200 years, humans have dramatically altered our global environmental envelope accidentally through uncontrolled greenhouse gas emissions. Humans have also developed the technology to both stop emitting greenhouse gases and ultimately to remove them from the atmosphere through a combination of natural and engineered pathways. Ultimately, humanity must practice CO2 removal in addition to maximal reduction in greenhouse gas emissions through conventional mitigation to achieve net-zero greenhouse gas emissions and ultimately net-negative emissions. To accomplish this task will require enormous sums of money and substantial cooperation between groups of people who commonly do not work together: technical experts, financiers, and government officials. In addition to heightened and accelerated ambition, humility is required as well. The task requires frequent and extended achievement in arenas that many scientists and engineers commonly understand only tangentially (e.g., lawmaking, regulatory enforcement, and project finance). PubDate: 2019-07-26T00:00:00Z
Authors:Rory Jacobson, Daniel L. Sanchez Abstract: Farming and ranching communities in the United States sit at the front lines of climate change impacts and responses. In particular, terrestrial atmospheric carbon dioxide removal (CDR) can reduce climate change impacts while increasing resilience to extreme weather. Currently, many CDR technologies and strategies are still under research and development (R&D), and lack sufficient federal support to reach widespread deployment. Here, we provide an assessment of the United States Department of Agriculture's (USDA) existing programs and organizational structure, its capacity to support research and demonstration of CDR, and recommendations for expansion of these capabilities. We summarize USDA's previous and current efforts to incorporate CDR R&D within their research, education, and economics mission, as well as opportunities to refocus and expand existing programs. Potential future actions to expand CDR R&D capabilities include: (1) the establishment of a new extramural research agency and an intramural technology commercialization program within USDA, (2) improved coordination between the Foundation for Food and Agriculture (FFAR) and USDA, (3) improved intra-agency and inter-agency coordination, and (4) congressional action to establish and fund new CDR programs within USDA. USDA can pursue multiple strategies to enhance CDR, driving development, demonstration, and deployment across the United States. PubDate: 2019-07-25T00:00:00Z
Open Access journal
