Microsoft’s million-tonne CO2-removal purchase — lessons for net zero

Researchers summarize the lessons learned from Microsoft’s carbon-removal efforts, along with those from another early corporate procurement — the $9-million purchases of carbon removal in 2020 and 2021 by the US–Irish financial-infrastructure company Stripe. The study highlights three ‘bugs’ in the current system: inconsistent definitions of net zero, poor measurement and accounting of carbon, and an immature market in CO2 removal and offsets. These challenges need to be overcome if the world is to reach net zero by mid-century. First, the supply of solutions capable of removing and storing carbon viably is a tiny proportion of that needed to reach global net-zero emissions by 2050 (which is an anticipated 2–10 gigatonnes of CO2 per year)2. Although Microsoft received 189 proposals offering 154 megatonnes of CO2 (MtCO2) over the coming years, only 55 MtCO2 were available immediately, and a mere 2 MtCO2 met Microsoft’s criteria for high-quality CO2 removal. Stripe’s 47 carbon-removal proposals amounted to 16 MtCO2, but only 0.024 MtCO2 met the company’s requirement that carbon remain sequestered for at least 1,000 years. Second, the scarcity of proposals that met the companies’ criteria reflects a lack of standards and clear definitions. Roughly one-fifth of proposals to Microsoft focused on avoiding new emissions, not on withdrawing CO2 from the atmosphere; these were rejected. Others lacked the technical information needed to ensure reliability. Indeed, there’s no standard way to measure, report and verify carbon removed. Such ambiguity is a barrier to investment. Third, systems for accounting for carbon removal do not distinguish between short- and long-term forms of CO2 storage (see ‘Some carbon-removal strategies’). This distorts the market and discourages investments in more-durable solutions. Nature-based storage projects sequestering carbon for less than 100 years accounted for most proposals that Microsoft received (in total, more than 95% of CO2 volume). It is cheaper and easier to establish trees and enrich soils than to deploy nascent technologies that capture carbon and store it geologically. https://www.nature.com/articles/d41586-021-02606-3