Last year, our planet surpassed 1.5 degrees Celsius of warming compared to preindustrial levels. This significant threshold heightens the risk of severe climate events such as wildfires, droughts, and floods becoming more common and dangerous. In order to keep global warming at or below 1.5°C and prevent catastrophic consequences, the nearly 200 countries that signed the Paris Agreement will need to make substantial reductions in greenhouse gas emissions, as well as implement effective carbon dioxide (CO2) removal strategies.
Previous studies focusing on climate mitigation have primarily examined three strategies for carbon dioxide removal (CDR): bioenergy with carbon capture and storage (BECCS), where CO2-absorbing plants are transformed into fuel or burned for energy, capturing part of the carbon for long-term storage; afforestation/reforestation, in which large quantities of CO2-absorbing trees are planted; and direct air carbon capture and storage (DACCS), a method that extracts CO2 from the air for sequestration or product creation.
A newly published study from the MIT Center for Sustainability Science and Strategy (CS3) broadens the scope of potential CDR options by including biochar (a charcoal-like substance made from biomass that is stored in soil) and enhanced weathering (EW), which involves applying finely ground minerals on land to facilitate CO2 storage in soil and water. This research evaluates the effectiveness of all five CDR strategies individually and in combination to determine their potential to meet the 1.5°C target as well as their effects on land use, energy, and overall policy costs.
The findings, appearing in Environmental Research Letters, provide essential insights aided by the global multi-region Economic Projection and Policy Analysis (EPPA) model used by MIT CS3 researchers.
One key conclusion emphasizes that diversifying CDR portfolios is the most cost-efficient and low-impact approach for policymakers striving toward net-zero emissions—a critical milestone to achieving the 1.5°C goal. This method reduces overall demands on cropland and energy while mitigating negative consequences such as increased food scarcity and limited energy resources.
By implementing a diverse array of CDR strategies, projections indicate that the highest possible deployment of around 31.5 gigatons of CO2 removal per year could be reached by 2100, making it the most economically viable route to net-zero emissions. The study positions BECCS and biochar as the most cost-effective methods for atmospheric CO2 removal, with EW following, while DACCS lags behind due to its high capital costs and energy requirements. Importantly, both biochar and EW also show promise for enhancing soil quality and agricultural productivity across approximately 45 percent of croplands by 2100.
“The key to cost-effective net-zero strategies lies in diversifying CDR portfolios. This strategy minimizes dependence on a single approach, thus lessening the strain on agriculture, forestry, and land use as well as the energy sector,” states Solene Chiquier, the study’s lead author and former CS3 postdoctoral researcher.
The second major finding reveals that there is no universally optimal CDR portfolio; effectiveness hinges on local technological, economic, and geophysical conditions. For instance, afforestation and reforestation are particularly advantageous in regions like Brazil and Africa, promoting both carbon sequestration and ecological health.
“When formulating a sustainable, cost-efficient CDR portfolio, it is crucial to consider the local availability of agricultural, energy, and carbon-storage resources,” explains Sergey Paltsev, CS3 deputy director and senior research scientist at the MIT Energy Initiative. “Our research underscores the necessity of enhancing awareness about local factors that influence the suitability of various CDR options.”
Lastly, the researchers caution that postponing large-scale deployment of CDR strategies can lead to significantly higher global carbon pricing—an impediment to crucial climate mitigation efforts necessary for confronting the 1.5°C challenge. They advocate for immediate policy and financial incentives to expedite the implementation of these essential strategies.
Photo credit & article inspired by: Massachusetts Institute of Technology
