Unleakable carbon^†

† The research was conducted at Department of Earth and Environment, Boston University, Commonwealth Avenue, Boston, MA 02215, USA.

Abstract

Unleakable carbon, or the uncombusted methane and carbon dioxide associated with fossil fuel systems, constitutes a potentially large and heretofore unrecognized factor in determining use of Earth’s remaining fossil fuel reserves. Advances in extraction technology have encouraged a shift to natural gas, but the advantage of fuel switching depends strongly on mitigating current levels of unleakable carbon, which can be substantial enough to offset any climate benefit relative to oil or coal. To illustrate the potential warming effect of methane emissions associated with utilizable portions of our remaining natural gas reserves, we use recent data published in peer-reviewed journals to roughly estimate the impact of these emissions. We demonstrate that unless unleakable carbon is curtailed, up to 59–81% of our global natural gas reserves must remain underground if we hope to limit warming to 2°C from 2010 to 2050. Successful climate change mitigation depends on improved quantification of current levels of unleakable carbon and a determination of acceptable levels of these emissions within the context of international climate change agreements.

Policy relevance

It is imperative that companies, investors, and world leaders considering capital expenditures and policies towards continued investment in natural gas fuels do so with a complete understanding of how dependent the ultimate climate benefits are upon increased regulation of unleakable carbon, the uncombusted carbon-based gases associated with fossil fuel systems, otherwise referred to as ‘fugitive’, ‘leaked’, ‘vented’, ‘flared’, or ‘unintended’ emissions. Continued focus on combustion emissions alone, or unburnable carbon, undermines the importance of assessing the full climate impacts of fossil fuels, leading many stakeholders to support near-term mitigation strategies that rely on fuel switching from coal and oil to cleaner burning natural gas. The current lack of transparent accounting of unleakable carbon represents a significant gap in the understanding of what portions of the Earth’s remaining global fossil fuel reserves can be utilized while still limiting global warming to 2°C. Successful climate change mitigation requires that stakeholders confront the issue of both unburnable and unleakable carbon when considering continued investment in and potential expansion of natural gas systems as part of a climate change solution.

Keywords:

• carbon accounting
• carbon leakage
• climate change mitigation
• emissions accounting
• emissions reduction
• GHG reporting

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Corrigendum

Acknowledgements

The Barr Foundation and Conservation Law Foundation supported this research. Lucy Hutyra, Anne Short Gianotti, and Sucharita Gopal provided helpful comments on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed at https://doi.org/10.1080/14693062.2016.1202808.

Notes

† The research was conducted at Department of Earth and Environment, Boston University, Commonwealth Avenue, Boston, MA 02215, USA.

Additional information

Funding

This publication was developed under STAR Fellowship Assistance Agreement [grant number F13F31263] awarded by the U.S. Environmental Protection Agency (EPA). It has not been formally reviewed by the EPA.