The risks of relying on tomorrow’s ‘negative emissions’ to guide today’s mitigation action

The paper argues that relying on future large-scale negative emissions to 'undo' current carbon emissions is a high-risk strategy that may lead to insufficient near-term decarbonization. It identifies three primary risk types: technological/biophysical infeasibility, unacceptable social and ecological impacts, and the potential for sequestered carbon to be re-released or for climate impacts to become irreversible. The authors evaluate four land-based options, concluding that while ecosystem restoration and reforestation may provide some viable negative emissions, high-reliance scenarios (e.g., those requiring 1,000 Gt CO2) are likely unachievable. BECCS is highlighted as particularly risky due to unproven commercial scale and extreme land and resource requirements. The paper advocates for a 'zero fossil carbon' goal over 'net zero' to ensure aggressive immediate mitigation.

• The authors identify three sequential risks in relying on negative emissions: technical or biophysical infeasibility, unacceptable social and ecological impacts, and the risk that the measures are less effective than expected due to carbon reversal or irreversible climate impacts.
• Many climate mitigation pathways aiming for 1.5°C or 2°C assume negative emissions as high as 1,000 Gt CO2, but the authors find these levels cannot be safely relied upon and may be unachievable due to biophysical constraints.
• Bioenergy with carbon capture and sequestration (BECCS) is considered high-risk because it has not been proven at a commercial scale and relies on industrial-scale thermochemical gasification that faces significant logistical and infrastructure challenges.
• Large-scale land-based negative emissions pose significant risks to food security, biodiversity, and the rights of indigenous peoples, with some estimates suggesting land requirements up to twice the world's currently cultivated land.
• Terrestrial carbon sinks are inherently insecure and vulnerable to re-release through human actions or natural disturbances like fire and drought, which are exacerbated by climate change.
• The authors suggest that 1.5°C pathways might be achievable if they rely on a lower range of negative emissions (370 to 480 Gt CO2) derived from reforestation and ecosystem restoration, avoiding the higher risks associated with BECCS.
• A 'zero fossil carbon' goal is argued to be more robust than a 'net zero' goal because it provides an unambiguous signal for decarbonization and avoids the risk of insufficient action based on the promise of future carbon removals.
• The biophysical upper limit for primary bioenergy supply is estimated at approximately 190 EJ/year, with a total potential including residues of about 250 EJ/year, yet some climate models assume potentials as high as 1,000 EJ/year.

APA

Kartha, S., & Dooley, K. (2016). The risks of relying on tomorrow’s ‘negative emissions’ to guide today’s mitigation action. Stockholm Environment Institute. https://www.sei.org/mediamanager/documents/Publications/Climate/SEI-WP-2016-08-Negative-emissions.pdf

Chicago

Kartha, Sivan, and Kate Dooley. The risks of relying on tomorrow’s ‘negative emissions’ to guide today’s mitigation action. Stockholm Environment Institute, 2016. https://www.sei.org/mediamanager/documents/Publications/Climate/SEI-WP-2016-08-Negative-emissions.pdf.

Wikipedia

{{cite report |last1=Kartha |first1=Sivan |last2=Dooley |first2=Kate |title=The risks of relying on tomorrow’s ‘negative emissions’ to guide today’s mitigation action |publisher=Stockholm Environment Institute |date=August 2016 |url=https://www.sei.org/mediamanager/documents/Publications/Climate/SEI-WP-2016-08-Negative-emissions.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{kartha2016risks, author = {Kartha, Sivan and Dooley, Kate}, title = {{The risks of relying on tomorrow’s ‘negative emissions’ to guide today’s mitigation action}}, institution = {Stockholm Environment Institute}, year = {2016}, month = aug, url = {https://www.sei.org/mediamanager/documents/Publications/Climate/SEI-WP-2016-08-Negative-emissions.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }