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News & views receptor-binding domain of the spike protein Master of Public Health program, Cornell 7. Ju, B. et al. https://doi.org/10.1038/s41586-020- that has an attached carbohydrate molecule. University, Ithaca, New York 14853, USA. Susan 2380-z (2020). 8. Yuan, M. et al. Science 368, 630–633 (2020). This region is not part of the key area that Daniel is in the Smith School of Chemical and 9. Baum, A. et al. Science https://doi.org/10.1126/science. directly binds to ACE2. The site that S309 rec- Biomolecular Engineering, Cornell University, abd0831 (2020). ognizes is evolutionarily conserved in spike Ithaca, New York 14853, USA. 10. Rogers, T. F. et al. Science https://doi.org/10.1126/science. abc7520 (2020). proteins across a range of bat coronaviruses e-mail: [email protected] 11. Brouwer, P. J. M. et al. Science https://doi.org/10.1126/ (in the genus Betacoronavirus lineage B; sub- science.abc5902 (2020). genus Sarbecovirus) that have similarities to 12. Hansen, J. et al. Science https://doi.org/10.1126/science. abd0827 (2020). the SARS-like coronaviruses. This raises the 1. Pinto, D. et al. Nature 583, 290–295 (2020). 13. Wec, A. Z. et al. Science https://doi.org/10.1126/science. possibility that such an antibody could have 2. Robbiani, D. F. et al. Nature https://doi.org/10.1038/ abc7424 (2020). s41586-020-2456-9 (2020). wide applicability in tackling related viruses. 14. Kelley, B. Nature Biotechnol. 38, 540–545 (2020). 3. Casadevall, A. & Pirofski, L. A. J. Clin. Invest. 130, 15. Furuyama, W. et al. Sci. Rep. 6, 20514 (2016). Not only, then, is this antibody of interest when 1545–1548 (2020). 16. Saphire, E. O. et al. Cell 174, 938–952 (2018). investigating ways to manage the COVID-19 4. Watanabe, Y. et al. Nature Commun. 11, 2688 (2020). 17. Mulangu, S. et al. N. Engl. J. Med. 381, 2293–2303 (2019). 5. ter Meulen, J. et al. PLoS Med. 3, e237 (2006). pandemic in the years ahead, but it might also 6. Shi, R. et al. Nature https://doi.org/10.1038/s41586-020- be considered for use in preventing future out- 2381-y (2020). This article was published online on 22 June 2020. breaks of related animal viruses, if they make the leap to causing infection in humans. Environmental science Ultimately, it seems unlikely that a robust treatment for COVID-19 will rely on a single antibody. Rather, as was the case for SARS, Atmospheric CO removed a synergistic approach combining different 2 monoclonal antibodies in an antibody cocktail might be more effective5. For such approaches by weathering to move forwards, evidence of effective anti- body neutralization from in vitro studies will Johannes Lehmann & Angela Possinger be needed, along with in vivo data assessing how well an antibody can boost other aspects Large-scale removal of from the of the immune response — by enlisting other might be achieved through enhanced rock weathering. It now immune cells to tackle the infection, for exam- seems that this approach is as promising as other strategies, ple. There are many promising avenues to explore in these efforts. in terms of cost and CO2-removal potential. See p.242 Pinto and colleagues got a head start with their work by exploring pre-existing anti­ bodies, and they should now have more B-cell Achieving targets for mitigating global risks, such as the possible release of metals and populations to mine. Many other teams, to warming will require the large-scale withdrawal persistent organic compounds (compounds give just some examples2,6–13, have also pre- of carbon dioxide from the atmosphere. On resistant to environmental degradation). sented useful discoveries in the hunt for page 242, Beerling et al.1 report that enhanced Despite the enthusiasm the authors’ find- antibodies that can target SARS-CoV-2. The rock weathering in has substantial techni- ings might generate, it is crucial to stress that, next steps will be to test individual antibod- cal and economic potential as a global strategy even under optimistic assumptions, enhanced ies and antibody cocktails in animal models, for removing atmospheric CO2. When crushed rock weathering will sequester only some of to determine whether they offer protection, or other material is added to the annual global carbon emissions from and then to assess their safety and effective- , it slowly dissolves and reacts with CO2 -fuel use. Therefore, reducing these ness in human clinical trials. An accelerated to form carbonates. These either remain emissions should still be the top priority for path might narrow the time lag between anti- in the soil or move towards the . The averting dangerous change. But, as body discovery and proof-of-concept trials authors argue that this method would enable Beerling et al. note, any approach is insuffi- 14 in humans to as little as five or six months . between 0.5 billion and 2 billion tonnes of CO2 cient alone, and should be considered as part The most recent prominent example to be removed from the atmosphere each year. of a portfolio of options. of immunotherapy for infectious disease This rate is similar to that of other land-based Several other land-based carbon-seques- relates to battling the Ebola virus. In con- approaches2, such as the accrual of organic tration techniques rely on soils. However, cert with vaccines and conventional, carbon in soil, carbon capture and sequestra- inorganic- by rock small-molecule-drug trials, the development tion in geological formations, and the addition weathering is fundamentally different from of monoclonal-antibody­ therapies for Ebola of biochar (a carbon-rich material) to soil. organic-carbon sequestration. The latter relies has progressed rapidly. Cocktails of anti­ Beerling and colleagues find that removing on photosynthesis by plants to remove CO2 bodies, beginning with one called ZMapp, atmospheric CO2 through enhanced from the atmosphere, and on soils to retain the that target a key Ebola viral protein called GP rock weathering would cost, on average, plant carbon, mostly in the form of microbial in two crucial regions of the protein, are con- US$160–190 per tonne of CO2 in the United remains. In the future, therefore, scientists tinuing to be developed15–17. This progress in States, Canada and , and $55–120 per should pay closer attention to what they mean efforts to tackle Ebola gives hope for similar tonne of CO2 in China, India, Mexico, Indonesia by ‘carbon sequestration’ — is it inorganic or immunotherapy­ achievements in targeting and Brazil. Furthermore, the authors report organic?

SARS-CoV-2. Pinto and colleagues’ work marks that China, the United States and India — the The sequestration of atmospheric CO2 a major step towards that much-anticipated, three largest emitters of CO2 from fossil-fuel through enhanced rock weathering shares and much-needed, success. use — have the highest potential for CO2 some of the principal appeal, but also the removal using this method. However, they also challenges, of organic-carbon sequestra- Gary R. Whittaker is in the Department of note that the application of silicate material to tion. The fact that crop production benefits Microbiology and Immunology, and in the soil (Fig. 1) requires careful assessment of the is certainly a key asset of both methods. In the

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case of enhanced rock weathering, the added rock contains essential plant nutrients, such as calcium and magnesium, as well as potas- sium and micronutrients that promote crop production in several ways. We would go even further than the authors do, to claim that these nutrients are currently insufficiently supplied in agriculture. Increasing soil pH alone would substantially boost crop yields in many regions of the , because it is possible that low pH constrains crop production on more than 200 mil- lion hectares of arable and orchard soils3. This area is equivalent to about 20% of the total extent of these soils (967 million hectares; see go.nature.com/31rcajd). Consequently, on a global scale, acidity is the most important soil constraint for agriculture4. However, there have been no detailed multi-regional analyses of the difference in crop yield between low-pH

ILSA B KANTOLA ILSA and optimum-pH soils, and such investigations would benefit the study of synergies between Figure 1 | Application of silicate material to cropland. Beerling et al.1 demonstrate that enhanced rock carbon-sequestration methods. The proposed weathering, achieved by adding crushed basalt or other silicate material to soil, is an effective strategy for rock additions could conceivably mitigate the removing carbon dioxide from the atmosphere. low use and supply shortages of agricultural in several regions5. Furthermore, yields even decrease, where incentives fail to production, and are centred around managing calcium improves root growth in acidic sub- persuade farmers, or where supply chains soils. Farmers must be fully behind such a surface soil6, with crucial knock-on effects break down. But scientists should not be global effort or it will fail. Scientists might through greater uptake by plant roots. deterred from evaluating such technologies, need to recognize that climate-change miti- Co-deployment of enhanced rock and should instead accept that farmers need to gation is not a sufficient incentive on its own, weathering with other soil-based seques- be in the driving seat in adapting soil manage- and that benefits to crop growth will need to be tration approaches might both reduce ment to meet their specific site and crop-pro- prioritized, as will financial incentives. Such an limitations and maximize synergies7. Beerling duction goals. A concerted global effort will be approach of financially supporting soil health and colleagues’ study hints at some of these required to develop site-specific optimization and crop production could emerge as our best opportunities and at constraints that have through farmer-centred research. near-term solution to the problem of removing

procedural and soil-biogeochemical aspects. Fertilizer distribution networks are CO2 from the atmosphere. Greater crop growth will increase the input of common in many parts of the world. But even crop residue (the materials from crops that are Johannes Lehmann is in the Department of left in a field after harvesting) to the soil, and “China, the United States Soil and Crop Sciences, School of Integrative thereby enhance the accrual of organic car- Plant Science, Cornell University, Ithaca, bon. However, the possibility that interactions and India have the highest New York 14853, USA. Angela Possinger is between calcium and organic matter impede potential for CO2 removal in the Department of Forest Resources and the return of CO2 to the atmosphere has been using this method .” Environmental Conservation, Virginia Tech, sparsely explored, and there is little informa- Blacksburg, Virginia 24061, USA. tion on the effects of magnesium. In princi- e-mail: [email protected] ple, calcium can reduce the where these networks are in place, success in of organic matter by facilitating adsorption to the adoption of enhanced rock weathering , inclusion in carbonates or aggregation8. might not rely on its crop-production bene- But the indirect effects of calcium through fits alone. We posit that carbon markets are 1. Beerling, D. J. et al. Nature 583, 242–248 (2020). changes in microbial or interactions required, and that it would be helpful if they 2. Pacala, S. et al. Negative Emissions Technologies and with organic compounds, rather than inter­ incentivized socially and environmentally Reliable Sequestration: A Research Agenda (National actions only between organic compounds and sound implementation10. For technologies to Academy of Sciences, 2018). 3. von Uexküll, H. R. & Mutert, E. Plant Soil 171, 1–15 (1995). clay , are rarely studied. be eligible, it must be shown that they provide 4. , S., Sebastian, K. & Scherr, S. J. Pilot Analysis of If the synergy becomes a trade-off between extra incentives for adoption (additionality), Global : Agroecosystems (World Resources Inst., 2000). organic-carbon sequestration and crop pro- beyond what increased soil fertility would 5. Fabregas, R., Kremer, M., Robinson, J. & Schilbach, F. duction, the organic-carbon content of soil deliver. We emphasize that implementation Evaluating Agricultural Information Dissemination could decrease, threatening the livelihoods of of enhanced rock weathering and other soil- in Western Kenya (International Initiative for Impact Evaluation, 2017). farmers, and even food security. Any carbon based carbon sequestration must consider 6. Lynch, J. P. & Wojciechowski, T. J. Exp. Bot. 66, 2199–2210 sequestration involving soils is a formidable equitable and financially sound incentives for (2015). challenge to incentivize, predict and monitor9, farmers that overcome challenges of addition- 7. Amann, T. & Hartmann, J. Biogeosciences 16, 2949–2960 10 (2019). because the sequestration technologies must ality, among others , in a proactive way. 8. Rowley, M. C., Grand, S. & Verrecchia, É. P. be used on vast areas of land that are operated Consequently, the main lesson here might Biogeochemistry 137, 27–49 (2018). by hundreds of millions of farmers. Inevita- be that several of the major potential tech- 9. Bradford, M. A. et al. Nature Sustain. 2, 1070–1072 (2019). 10. Cavanagh, C. J., Vedeld, P. O., Petursson, J. G. & bly, there will be individual cases in which nologies for removing atmospheric CO2 Chemarum, A. K. J. Peasant Stud. https://doi.org/10.1080/ positive-yield projections are not met or crop could generate substantial benefits for food 03066150.2019.1707812 (2020).

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