Environmental Sciences

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    Success of coastal wetlands restoration is driven by sediment availability
    (Springer Nature, 2021-02-23) Liu, Zezheng; Fagherazzi, Sergio; Cui, Baoshan
    Shorelines and their ecosystems are endangered by sea-level rise. Nature-based coastal protection is becoming a global strategy to enhance coastal resilience through the cost-effective creation, restoration and sustainable use of coastal wetlands. However, the resilience to sea-level rise of coastal wetlands created under Nature-based Solution has been assessed largely on a regional scale. Here we assess, using a meta-analysis, the difference in accretion, elevation, and sediment deposition rates between natural and restored coastal wetlands across the world. Our results show that restored coastal wetlands can trap more sediment and that the effectiveness of these restoration projects is primarily driven by sediment availability, not by wetland elevation, tidal range, local rates of sea-level rise, and significant wave height. Our results suggest that Nature-based Solutions can mitigate coastal wetland vulnerability to sea-level rise, but are effective only in coastal locations where abundant sediment supply is available.
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    Nuclear Niño response observed in simulations of nuclear war scenarios
    (Springer Nature, 2021-01-22) Coupe, Joshua; Stevenson, Samantha; Lovenduski, Nicole S.; Rohr, Tyler; Harrison, Cheryl S.; Robock, Alan; Oliviarez, Holly; Bardeen, Charles G.; Toon, Owen B.
    The climate impacts of smoke from fires ignited by nuclear war would include global cooling and crop failure. Facing increased reliance on ocean-based food sources, it is critical to understand the physical and biological state of the post-war oceans. Here we use an Earth system model to simulate six nuclear war scenarios. We show that global cooling can generate a large, sustained response in the equatorial Pacific, resembling an El Niño but persisting for up to seven years. The El Niño following nuclear war, or Nuclear Niño, would be characterized by westerly trade wind anomalies and a shutdown of equatorial Pacific upwelling, caused primarily by cooling of the Maritime Continent and tropical Africa. Reduced incident sunlight and ocean circulation changes would cause a 40% reduction in equatorial Pacific phytoplankton productivity. These results indicate nuclear war could trigger extreme climate change and compromise food security beyond the impacts of crop failure.
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    Ecological resilience of restored peatlands to climate change
    (Springer Nature, 2022-09-13) Loisel, Julie; Gallego-Sala
    Degradation of peatlands through land-use change and drainage is currently responsible for 5-10% of global annual anthropogenic carbon dioxide emissions. Therefore, restoring disturbed and degraded peatlands is an emerging priority in efforts to mitigate climate change. While restoration can revive multiple ecosystem functions, including carbon storage, the resilience of restored peatlands to climate change and other disturbances remains poorly understood. Here, we review the recent literature on the response of degraded and restored peatlands to fire, drought and flood. We find that degraded sites can generally be restored in a way that allows for net carbon sequestration. However, biodiversity, hydrological regime, and peat soil structure are not always fully restored, even after a decade of restoration efforts, potentially weakening ecosystem resilience to future disturbances. As the recovery of degraded peatlands is fundamental to achieving net-zero goals and biodiversity targets, sound science and monitoring efforts are needed to further inform restoration investments and priorities.
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    A function-based typology for Earth’s ecosystems
    (Springer Nature, 2022-10-12) Keith, David A; Ferrer-Paris, José R.; Nicholson, Emily; Bishop, Melanie J.; Polidoro, Beth A.; Ramirez-Llodra, Eva; Tozer, Mark G.; Nel, Jeanne L.; Mac Nally, Ralph; Gregr, Edward J.; Watermeyer, Kate E.; Essl, Franz; Faber-Langendoen, Don; Franklin, Janet; Lehmann, Caroline E. R.; Etter, Andrés; Roux, Dirk J.; Stark, Jonathan S.; Rowland, Jessica A.; Brummitt, Neil A.; Frenandez-Arcaya, Ulla C.; Suthers, Iain M.; Wiser, Susan K.; Donohue, Ian; Jackson, Leland J.; Pennington, R. Toby; Iliffe, Thomas M.; Gerovasileiou, Vasilis; Giller, Paul; Robson, Belinda J.; Pettorelli, Nathalie; Andrade, Angela; Lindgaard, Arild; Tahvanainen, Teemu; Terauds, Aleks; Chadwick, Michael A.; Murray, Nicholas J.; Moat, Justin; Plisoff, Patricio; Zager, Irene; Kingsford, Richard T.
    As the United Nations develops a post-2020 global biodiversity framework for the Convention on Biological Diversity, attention is focusing on how new goals and targets for ecosystem conservation might serve its vision of ‘living in harmony with nature’. Advancing dual imperatives to conserve biodiversity and sustain ecosystem services requires reliable and resilient generalizations and predictions about ecosystem responses to environmental change and management3. Ecosystems vary in their biota4, service provision5 and relative exposure to risks6, yet there is no globally consistent classification of ecosystems that reflects functional responses to change and management. This hampers progress on developing conservation targets and sustainability goals. Here we present the International Union for Conservation of Nature (IUCN) Global Ecosystem Typology, a conceptually robust, scalable, spatially explicit approach for generalizations and predictions about functions, biota, risks and management remedies across the entire biosphere. The outcome of a major cross-disciplinary collaboration, this novel framework places all of Earth’s ecosystems into a unifying theoretical context to guide the transformation of ecosystem policy and management from global to local scales. This new information infrastructure will support knowledge transfer for ecosystem-specific management and restoration, globally standardized ecosystem risk assessments, natural capital accounting and progress on the post-2020 global biodiversity framework.
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    Enhanced silica export in a future ocean triggers global diatom decline
    (Springer Nature, 2022-05-25) Taucher, Jan; Bach, Lennart T.; Prowe, A. E. Friederike; Boxhammer, Tim; Kvale, Karin; Riebesell
    Diatoms account for up to 40% of marine primary production and require silicic acid to grow and build their opal shell. On the physiological and ecological level, diatoms are thought to be resistant to, or even benefit from, ocean acidification. Yet, global-scale responses and implications for biogeochemical cycles in the future ocean remain largely unknown. Here we conducted five in situ mesocosm experiments with natural plankton communities in different biomes and find that ocean acidification increases the elemental ratio of silicon (Si) to nitrogen (N) of sinking biogenic matter by 17 ± 6 per cent under pCO2 conditions projected for the year 2100. This shift in Si:N seems to be caused by slower chemical dissolution of silica at decreasing seawater pH. We test this finding with global sediment trap data, which confirm a widespread influence of pH on Si:N in the oceanic water column. Earth system model simulations show that a future pH-driven decrease in silica dissolution of sinking material reduces the availability of silicic acid in the surface ocean, triggering a global decline of diatoms by 13–26 per cent due to ocean acidification by the year 2200. This outcome contrasts sharply with the conclusions of previous experimental studies, thereby illustrating how our current understanding of biological impacts of ocean change can be considerably altered at the global scale through unexpected feedback mechanisms in the Earth system.