Cities lean on carbon removal, fields hold phosphorus, and sea sugars reach the clouds

Net-zero plans without numbers on removal

An analysis of climate-neutrality plans from 103 European cities aiming at net zero by 2030 finds they intend to compensate a median 20 per cent of baseline emissions — 61.4 million tonnes of carbon dioxide equivalent in total — with carbon removal. Giulia Ulpiani and colleagues report in Nature Climate Change that only 18 per cent of that volume has a quantified removal behind it. The cities were selected under the EU mission for 100 climate-neutral and smart cities and span 30 countries; 61 trained experts read the plans against a common coding protocol. Half the residual emissions sit in stationary energy and 31 per cent in transport, sectors the authors describe as comparatively easy to abate. Every plan leans on temporary land-based removal such as tree planting; 40 per cent invoke carbon credits and 32 per cent name a permanent option — bioenergy with carbon capture at 27 per cent, biochar at 13 per cent and direct air capture at 7 per cent. The robustness index the authors build has a median of 0.5, and the plans carry no detailed assessment of how much urban land is actually available. The figures rest on coded plan text, not measured emission cuts.^[1]

Phosphorus sits in soil while reserves thin

Becca Muenich of the University of Arkansas and colleagues built a phosphorus account covering 3,142 counties from 1866 to 2050. Domestic reserves could be exhausted within 40 years, while recyclable sources add up to about 125 per cent of what has historically been spread on fields. Roughly 145 teragrams of phosphorus have been applied as fertiliser since 1866. As of 2023, 52 teragrams sit in cropland soils and 47 teragrams in pastureland. About 80 per cent of fertiliser phosphorus never reaches a crop, so the accumulation is a stock available for recovery. Muenich's emphasis is that no single technology suffices, because the phosphorus is scattered across very different environmental sources. The work was carried out with the STEPS centre at North Carolina State University and appears in Proceedings of the National Academy of Sciences. The exhaustion figure is a projection built on historical data, not a fixed calendar.^[2]

Marine sugars rise to cloud height

A team led by the Leibniz Institute for Tropospheric Research collected air samples between 300 and 1,000 m with the 12 m BELUGA balloon near Ny-Ålesund on Svalbard, and compared them with seawater and surface-film samples from Kongsfjorden. It is the first direct measurement showing marine sugars reaching cloud-forming heights. Samples were taken in autumn 2021 and spring 2022. As Manuela van Pinxteren describes it, combining ground-level and altitude aerosol measurements with the fjord water samples made ocean-to-atmosphere transport directly traceable for the first time. That some sugars may also form inside clouds through biological processes is a possibility the measurement supports rather than a demonstrated route. The team notes that comparable Antarctic measurements do not exist; the University of Cologne, the Alfred Wegener Institute and the Max Planck Institute for Marine Microbiology also took part. The work appears in Atmospheric Chemistry and Physics. City-plan removal shares, soil phosphorus stocks and Arctic sugars do not share one ledger; each shows where a human or ocean stock goes in its own unit.^{[3], [1], [2]}

Net-zero plans without numbers on removal

Phosphorus sits in soil while reserves thin

Marine sugars rise to cloud height

References

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