To address the global climate crisis, it is urgent to achieve carbon neutrality by the mid-21st century, balancing carbon emissions and carbon absorption from the atmosphere. This study examines the current advancements in biological methods for capturing carbon dioxide (CO2) in response to global climate change, emphasizing the importance of sequestering CO2 through biological carbon capture and utilization. First, we present an overview of typical carbon capture methods, including geological and oceanic carbon storage. We then highlight the significance of utilizing photosynthetic organisms, such as plants, algae and microorganisms, for carbon capture and sequestration. We also analyze the role of photosynthesis in carbon capture and explore the potential of microbial carbon capture, examining the impact of environmental factors on capture efficiency. Additionally, we discuss the development of symbiotic approaches to enhance carbon fixation capacity. Finally, this review provides key insights into the challenges and future directions in advancing the field of biological carbon capture to achieve carbon neutrality.

Hexavalent chromium (Cr6+) is a toxic carcinogenic pollutant that might be released by the mining and processing of ultramafic rocks and nickel laterites and which requires permanent removal from the contaminated biosphere. Ultramafic material can also serve as a feedstock for the sequestration of CO2 resulting from the growth of new minerals, raising the intriguing proposition of integrated sequestration of both pollutants, CO2 and chromium, into magnesium carbonates. Such a synergistic process downstream of ore recovery and mineral processing could be an elegant proposition for more sustainable utilisation and management of the Earth's resources. We have therefore carried out an experimental and microanalytical study to investigate potentially suitable carbonate minerals. Uptake of chromium in carbonate phases was determined, followed by identification of the crystalline phases and characterisation of the local structural environment around the incorporated chromium centres. The results suggest that neither nesquehonite nor hydromagnesite have the structural capacity to incorporate Cr6+ or Cr3+ significantly at room temperature. We therefore propose that further research into this technology should focus on laboratory assessments of other phases, such as layered double hyroxides, that have a natural structural capacity to uptake both chromium and CO2.

Technologies and practices to remove carbon from the atmosphere (‘negative emissions technologies’) will be challenging to scale-up. Efforts to incentivize or govern their scale-up globally risk failing if they miss the social challenges. This paper analyzes prospective challenges for negative emissions through examining how decarbonization practices are evolving in one particular landscape: the Imperial Valley in southeast California, a desert landscape engineered for industrial agriculture. Based on semi-structured interviews and site visits, this paper examines how community actors have received, participated in, imagined or contested new energy technologies and climate practices, and draws out takeaways for negative emissions policy.