Communications Earth & Environment最新文献

Reduced and polymerized phosphorus species may have been crucial for the origin and early evolution of life, as they are more reactive and soluble than phosphate. Thermal processes could have produced these phosphorus species; however, the underlying mechanism is poorly constrained, and geological evidence of polymerized species in the Precambrian is so far absent. Here, we investigated contact-metamorphic rocks from the ca. 3.22 Ga Moodies Group (South Africa), where mafic dikes intruded into shallow-marine sediments. We provide evidence of magmatic phosphite (up to 2.85 ppm) and metamorphic polyphosphate (up to 39.3 ppm). Additional laboratory experiments suggest that carbon can facilitate the thermal production of polyphosphates and reduced phosphorus species, including phosphide, from less reactive minerals such as apatite and vivianite. We conclude that magmatic and thermal-metamorphic rocks could have provided soluble and reactive phosphorus species crucial for the origin and early evolution of life.

Passenger aviation carbon footprint calculators often lack breadth, accuracy, transparency, and communication effectiveness, leading to underestimations of environmental impact and mistrust. This study addresses these gaps by developing a comprehensive methodology that broadens scope and improves accuracy. It incorporates nitrogen oxides, water vapour, contrail-induced cloudiness, upstream emissions from in-flight services, and life cycle emissions from aircraft and airports, offering a complete carbon footprint assessment. Accuracy is improved through detailed modelling of flight distance, fuel consumption, and emissions allocation adjusted for passenger class, luggage, and cargo. Historical adjustment factors refine pre-flight estimates by integrating real-world variations. The tool outputs a full emissions breakdown by source, offering unparalleled granularity and clarity. Validated against over 30,000 historical flights, the historical adjustment factor model achieves ~0.5% mean squared percentage error and shows current methods underestimate emissions. This study sets a standard for aviation carbon footprint calculators by enabling transparent, dynamic assessments for industry stakeholders.

Decarbonizing the energy sector requires renewable sources that are economic and responsive to demand. Intermittency and seasonal variability, therefore, limit the potential of wind and solar. Geothermal energy can potentially provide low-carbon renewable power that is dispatchable and responsive to demand. However, conventional geothermal methods require high permeability in high-temperature subsurface zones, which restricts their application. Here, we assess the global potential of the closed-loop geothermal system (CLGS), an emerging technology that does not require high permeability. Using thermodynamic, process, and technoeconomic modeling, we analyze the potential for CLGS in 12,000 candidate regions to estimate global viability. With the base case of water as the working fluid in a Rankine cycle, we estimate the global potential to be 9 TWe, equivalent to 70% of current electricity production. We assess using phase change working fluids to broaden applicability and improve efficiency, and evaluate the remaining technological barriers to closed-loop geothermal energy production.

Explosive volcanic eruptions are a major geo-hazard. Given the energetic nature of eruptive processes, direct observation is limited, making the study of deposits and pyroclast textures essential for understanding eruption dynamics. Experimental constraints therefore provide a vital contribution to improving hazard assessment. We performed tumbling experiments using pumice lapilli from the Laacher See eruption (Eifel, Germany) to investigate ash generation and pyroclast shape evolution. Before and after each experimental step, samples were sieved, and the volume and four morphological parameters (axial ratio, convexity, form factor, solidity) of 100 clasts were measured. Most shape change happened before the first 15 min (first experimental step) and produced up to 48 wt.% ash. We frame our analysis in terms of effective relaxation timescales, whereby pyroclasts display a decelerating rate of shape change towards a time-invariant morphology. This quantification of the susceptibility of porous pyroclasts to changes enhances our understanding of transport processes from clast generation to sedimentation.

Fossils preserving soft tissues and lightly biomineralized structures are essential for the reconstruction of past ecosystems and their evolution. Understanding fossilization processes, including decay and mineralisation, is crucial for accurately interpreting ancient morphologies. Here we investigate the decay of marine and freshwater shrimps deposited on the surface of three different clay beds. In experimental set ups containing kaolinite, cryogenic scanning electron microscopy shows a black film comprised of newly formed anhedral and cryptocrystalline aluminosilicates on marine shrimp cuticles, which stabilise the overall morphology. This is the first experimental evidence for the replication of arthropod lightly biomineralized structures in aluminosilicates shortly after death, while carcasses are not buried by sediments. The preservation of morphology through aluminosilicates could result in carcasses persisting on the seafloor for weeks without losing much external anatomical information. In this context, instantaneous burial capturing animals alive may not be a prerequisite for exceptional preservation as usually thought.

Agriculture and food systems are major sources of plastic pollution but they are also vulnerable to their diverse lifecycle impacts. However, this problem is not well-recognized in global policy and scientific discourse, agendas, and monitoring of food systems. The United Nations-led Global Plastics Treaty, which has been under negotiation since 2022, is a critical opportunity to address pollution across the entire plastics lifecycle for more sustainable and resilient food systems. Here, we offer aspirational indicators for future monitoring of food systems' plastics related to (1) plastic polymers and chemicals, (2) land use, (3) trade and waste, and (4) environmental and human health. We call for interdisciplinary research collaborations to continue improving and harmonising the evidence base necessary to track and trace plastics and plastic chemicals in food systems. We also highlight the need for collaboration across disciplines and sectors to tackle this urgent challenge for biodiversity, climate change, food security and nutrition, health and human rights at a whole systems level.

The 2022 Hunga volcanic eruption injected a significant quantity of water vapor into the stratosphere while releasing only limited sulfur dioxide. It has been proposed that this excess water vapor could have contributed to global warming, potentially pushing temperatures beyond the 1.5 °C threshold of the Paris Climate Accord. However, given the cooling effects of sulfate aerosols and the contrasting impacts of ozone loss (cooling) versus gain (warming), assessing the eruption's net radiative effect is essential. Here, we quantify the Hunga-induced perturbations in stratospheric water vapor, sulfate aerosols, and ozone using satellite observations and radiative transfer simulations. Our analysis shows that these components induce clear-sky instantaneous net radiative energy losses at both the top of the atmosphere and near the tropopause. In 2022, the Southern Hemisphere experienced a radiative forcing of -0.55 ± 0.05 W m⁻² at the top of the atmosphere and -0.52 ± 0.05 W m⁻² near the tropopause. By 2023, these values decreased to -0.26 ± 0.04 W m⁻² and -0.25 ± 0.04 W m⁻², respectively. Employing a two-layer energy balance model, we estimate that these losses resulted in cooling of about -0.10 ± 0.02 K in the Southern Hemisphere by the end of 2022 and 2023. Thus, we conclude that the Hunga eruption cooled rather than warmed the Southern Hemisphere during this period.

Turbidity currents carve Earth's deepest canyons, form Earth's largest sediment deposits, and break seabed telecommunications cables. Directly measuring turbidity currents is notoriously challenging due to their destructive impact on instruments within their path. This is especially the case for canyon-flushing flows that can travel >1000 km at >5 m/s, whose dynamics are poorly understood. We deployed ocean-bottom seismometers safely outside turbidity currents, and used emitted seismic signals to remotely monitor canyon-flushing events. By analyzing seismic power variations with distance and signal polarization, we distinguish signals generated by turbulence and sediment transport and document the evolving internal speed and structure of flows. Flow-fronts have dense near-bed layers comprising multiple surges with 5-to-30-minute durations, continuing for many hours. Fastest surges occur 30-60 minutes behind the flow-front, providing momentum that sustains flow-fronts for >1000 km. Our results highlight surging within dense near-bed layers as a key driver of turbidity currents' long-distance runout.

Atmospheric amines, derivatives of ammonia, play a unique yet not fully understood role in air quality, climate and public health. Sub-5 parts per trillion Volume (pptV, <10^-12 in volume) mixing ratios of amines facilitate the physical and/or chemical transformation of aerosols in the atmosphere, enhancing aerosol formation and growth rates, aerosol hygroscopicity, and the activation of cloud condensation nuclei. This serves as the initial step for cloud droplet formation and, consequently, influences cloud properties and the hydrological cycle. Ambient observations demonstrate more than a thousand-fold particle formation rates in the presence of amines as compared to ammonia. Yet, the challenges related to detecting minute levels of amines, the paucity of ambient amine measurements, and the limited process-based understanding of airborne aerosol production have resulted in amines being underrepresented in global climate models. Therefore, advanced techniques with extremely low detection limits and highly spatially and temporally resolved ambient amine measurements globally in diverse environments are essential.

Arctic food systems blend Traditional Ecological Knowledge with modern, often energy-intensive influences, triggered by colonization. Food systems' future depends on alignment of tradition with innovation, facilitation of resilience and a heritage-driven interaction with the global economy - at a pace determined by local communities.