The SBTi net-zero standard should include guidance on carbon removal

Over the last few years, the Science Based Targets initiative (SBTi) has emerged as the leading private standard for defining and verifying credible net-zero targets by businesses and other sub-state actors. The SBTi standard requires companies to reduce value-chain emissions by around 90% and to neutralize residual CO₂ emissions using only permanent carbon removal. These requirements have helped reinforce the need to prioritize deep emission cuts, as well as the limited but important role of permanent carbon removal.

However, the SBTi net-zero standard as published in October 2021 also has room for improvement. In a letter that we originally shared with SBTi last fall and are publishing in an updated form today, 16 organizations representing carbon removal buyers, suppliers, non-profits, and academics call on SBTi to clarify both the requirements for what constitutes permanent carbon removal and the guidance on the role of permanent removals in near-term science-based targets — in essence, information to guide the next five to ten years of a company’s carbon removal strategy.

Our letter makes two broad recommendations. First, we ask that SBTi define permanent carbon removal as ensuring that CO₂ remains out of the atmosphere for at least 1,000 years. A ton of CO₂ emitted has an extremely long atmospheric residence time: around 20 to 30% will remain after 1,000 years, and it takes around half a million years for complete removal by natural carbon sinks. SBTi currently states that permanent removals should “ensure storage permanence for a timeframe that is commensurate with the duration that atmospheric GHG concentrations would be affected by the unabated emission.” We suggest that a threshold of 1,000+ years to qualify as permanent realistically meets this criteria. We also note that while permanence is one critical aspect of CDR, it is equally important that approaches are additional, verifiable, sustainable, and safe.

Second, we ask SBTi to define clear interim targets for neutralization as part of near-term science-based targets, at least for companies that expect to have some residual emissions at the point of net zero. There is no requirement in the current standard that companies invest today in scaling up neutralization as part of their targets, and little guidance on how, where, and why organizations can or should buy nascent, permanent carbon removal. Without additional guidance, we are worried that companies will focus solely on the lowest-cost beyond-value-chain-mitigation offset opportunities in the near-term and underinvest in permanent carbon removal technologies.

Figure 2 of the SBTI net-zero standard indicates that companies should invest in permanent carbon removal before their net-zero target date, but no explicit guidance is provided in the text. We recommend that SBTi’s Corporate Net-Zero Standard require organizations to plan ahead to quantify their expected residual emissions and establish interim permanent carbon removal purchase commitments as part of their near-term targets.

Figure 2 from the SBTi Net-Zero Standard.

Together, these changes would enhance the credibility of the SBTi standard by clarifying how net-zero aligned companies should approach near-term purchases of permanent carbon removal. Guidelines from a leading standard like SBTi could play an important role in facilitating the investment in permanent carbon removal that is needed to achieve mid-century, net-zero goals.

Update — Nov 28 2022

The Science Based Targets initiative posted a thoughtful acknowledgment that welcomes our letter, emphasizes the primacy of companies’ emission reductions in SBTi’s net-zero standard (which we fully support), and promises additional engagement in 2023. We look forward to the opportunity to work with SBTi and other stakeholders going forward, and appreciate SBTi’s leadership.