Communications Earth & Environment最新文献

Given the global offshore wind farm (OWF) proliferation, we investigated the impact of OWFs on the marine food web. Using linear inverse modelling (LIM), we compared the OWF food web with two soft-sediment food webs nearby. Novel in situ data on species biomass and their isotopic composition were combined with literature data to construct food webs. Our findings highlight the prominent role of hard-substrate species on turbine foundations as organic material inputs for the food web. Hard substrate species account for approximately 26% of food source uptake from the water column and increase carbon deposition on the surrounding seafloor by ~10%. OWFs facilitate a novel food web with a higher productivity than expected based on standing biomass alone, as a result of numerous interactions between a diverse species community. Our study underscores profound effects of OWFs on marine ecosystems, suggesting the need for further research into their ecological impacts.

Quantifying the ocean's ability to sequester atmospheric carbon is essential in a climate change context. Measurements of gravitational carbon export to the mesopelagic seldom balance the carbon demand or the oxygen consumption there, suggesting the potential presence of other mechanisms of carbon export. We deployed a biogeochemical Argo float in a cyclone in the Benguela upwelling system for five months, and estimated vertical carbon export and respiration in the eddy via particle imagery with an underwater vision profiler 6 in a quasi Lagrangian way. A sensitivity analysis shows that, under certain assumptions, oxygen consumption rates could match the carbon supply and carbon demand. We furthermore identified a mechanism of vertical particulate carbon export, the full eddy core submergence pump. Our analysis suggests that at 450 m depth, within this eddy, this pump exports about one fourth to half of the total carbon compared to the biological gravitational pump.

European farmers struggle with mitigating global emissions of greenhouse gases effectively and to cope with climate change. European regulators and national governments encounter obstacles in implementing environmental policies, feeding frustration amongst farmers. We hypothesize that these issues relate to climate change skepticism within the farming community and dissensus with non-farmers and between countries. To test this hypothesis, we analyzed climate attribution and impact skepticism amongst farmers and the rest of the working population using the Eurobarometer and the European Social Survey, and national data about gross domestic product (GDP), innovativeness, share of agricultural land, and climate damage risk for agriculture. Impact skepticism of farmers increases with decreasing risk of climate damage and increasing GDP, causing a South-North gradient in Europe. The majority of farmers in the EU countries were more skeptical than non-farmers. Understanding and reducing this skepticism provides a key to more effective mitigation and adaptation.

The history of resilience of organisms over geologic timescales serves as a reference for predicting their response to future conditions. Here we use fossil Porites coral records of skeletal growth and environmental variability from the subtropical Central Paratethys Sea to assess coral resilience to past ocean warming and acidification. These records offer a unique perspective on the calcification performance and environmental tolerances of a major present-day reef builder during the globally warm mid-Miocene CO₂ maximum and subsequent climate transition (16 to 13 Ma). We found evidence for up-regulation of the pH and saturation state of the corals' calcifying fluid as a mechanism underlying past resilience. However, this physiological control on the internal carbonate chemistry was insufficient to counteract the sub-optimal environment, resulting in an extremely low calcification rate that likely affected reef framework accretion. Our findings emphasize the influence of latitudinal seasonality on the sensitivity of coral calcification to climate change.

Coastal flooding is occurring more frequently due to global sea-level rise, among other factors. However, current understanding of coastal flood frequency and sea-level rise impacts is predominantly based on tide gauges, which do not measure water levels on land. Here, we present data from a novel network of land-based flood sensors in the state of North Carolina, USA. We demonstrate that tide-gauge data are poor indicators of flooding: floods occur 26-128 days annually, an order of magnitude greater than what regional tide gauges suggest in some places. Improving the accuracy of coastal flood measures is critical for identifying the impacts of sea-level rise and developing effective adaptation strategies.

Landforms created by flowing water with sediment have left deposits on the surface of Mars, allowing study of the ancient environment. These features could provide constraints on surface water activity and past habitability. However, only a few lab studies have investigated the appearance and behavior of sediment-rich flows at relevant Mars surface conditions. We conducted experiments in a Mars environment chamber to understand the rheology and deposit morphology of mud under atmospheric pressures from 5 to 1000 mbar and surface temperatures between 248 and 297 K. We found that sediment flows in the Noachian era, when most aqueous activity occurred, could behave similarly to Earth analogs, but only under certain climate conditions. However, in the Hesperian and Amazonian periods, the dominant physical regime changed due to global atmospheric loss. Sediment flows during these eras would not have been similar to Earth analogs, and would have been dominated by freezing, evaporative cooling, and boiling depending on the microclimate (local pressure and temperature). Thus, regional climate and compositional context are important factors for interpreting satellite remote sensing images of these features on Mars. The results suggest we may be able to discover the paleo-atmospheric pressure record on Mars by analyzing sediment flow morphology.

Wildfires are a key component of Earth system dynamics with respect to carbon cycling. Thus, reconstructing past wildfire dynamics is crucial for understanding potential future climate change as related to (paleo)environmental feedbacks. Here, we explore wildfire during the Early Triassic (Smithian and Spathian, ca. 250 million years ago) - a time interval characterized by scarce fire evidence, perturbation of the carbon cycle, climatic oscillations, vegetation succession and biotic radiation-extinction pulses - using polyaromatic hydrocarbons, which are an organic (geo)chemical fire indicator in sediments. Hydrocarbon abundances in shales from Spitsbergen show a prominent increase after the Smithian-Spathian boundary. Diagnostic ratios of hydrocarbons suggest that these compounds were derived from relatively unaltered biomass as opposed to soil erosion and petrogenic carbon inputs or coal combustion vis-à-vis a coincidental Siberian Trap volcanism. Our data indicates that as temperatures decline during the late Smithian, coeval hydrological conditions become less intense and changing vegetation successions become more amenable to wildfire activity. We hypothesize that changing regional wildfire regimes influenced biogeochemical cycles, potentially affecting long-term carbon sequestration. The observed coupled behavior in water-vegetation-wildfire systems amid key perturbations in Earth's history provides new insights into imminent future climate change consequences.

Antarctica, once considered pristine, is increasingly threatened by plastic pollution, with debris found in its waters, sediments, sea ice, and biota. Here, we provide a comprehensive molecular survey of both prokaryotic and eukaryotic diversity on plastics around the Antarctic Peninsula, addressing a gap in existing research. Using eDNA metabarcoding, we identified diverse communities, with Pseudomonadota and Bacteroidota dominating prokaryotic communities, while Gyrista (mostly diatoms), Fungi and Arthropods were prevalent among eukaryotes. Geographic location significantly influenced community composition, with differences between the Bransfield Strait and the Gerlache Strait/Bellingshausen Sea. Polymer type and plastic shape did not impact species richness or community structure. These findings offer new insights into the complexity of the Antarctic plastisphere, highlighting potential impacts on biodiversity, ecosystem functions, and the broader implications of marine plastic pollution.

Volcanic ash aggregation occurs during transport in the atmosphere when individual ash particles collide and stick together. It significantly impacts ash residence time in the atmosphere, with major consequences for hazard assessment and ash dispersal forecasts. Nonetheless, aggregation processes are still not adequately parametrized, mostly due to the low preservation potential of most aggregate types. We present here the first, detailed structural and morphological characterization of the major aggregate types, combining an innovative field collection strategy, which allows for the original aggregate structure to be preserved at deposition, coupled to X-Ray micro-tomography. Resulting observations together with weather information, allowed for the structure of fragile ash clusters and of the elusive cored Ash Pellets (cAP1s) to be fully resolved and their genesis to be better described. The collected dataset represents a fundamental advancement towards a comprehensive characterization of the principal aggregate categories, which is key to accurately interpreting and modelling the process of volcanic ash aggregation and dispersal.

Large Low Shear Velocity Provinces (LLSVPs) near the core-mantle boundary (CMB) are key yet enigmatic structures. Their origin is often linked to the accumulation of subducted mid-ocean ridge basalt (MORB), but computational models question MORB as the sole source due to its predicted high shear wave velocity compared to normal mantle. This uncertainty is compounded by the lack of direct sound velocity measurements at CMB pressures. Here we address this gap through ultrahigh-pressure shear wave velocity measurements on CaCl₂- and α-PbO₂-type SiO₂, major phases in MORB, at pressures exceeding those of the CMB. Our results show shear velocities in dense SiO₂ phases are ~ 7-14% lower than previous predictions under these conditions. Incorporating these values into MORB models suggests that the typical seismic anomaly of -1.5% (δlnV _S ) observed in LLSVPs can be explained by ~ 23-33 vol.% oceanic crust along a cold slab geotherm, without invoking extreme thermal anomalies (+1500 K). Considering a subduction history exceeding 2 billion years, this scenario supports long-term MORB accumulation at the lowermost mantle. These findings provide new constraints on LLSVP composition and offer critical insights into deep mantle dynamics and the evolution of Earth's interior.