Communications Earth & Environment最新文献

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.

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.

Questions about when early members of the genus Homo adapted to extreme environments like deserts and rainforests have traditionally focused on Homo sapiens. Here, we present multidisciplinary evidence from Engaji Nanyori in Tanzania's Oldupai Gorge, revealing that Homo erectus thrived in hyperarid landscapes one million years ago. Using biogeochemical analyses, precise chronometric dating, palaeoclimate simulations, biome modeling, fire history reconstructions, palaeobotanical studies, faunal assemblages, and archeological evidence, we reconstruct an environment dominated by semidesert shrubland. Despite these challenges, Homo erectus repeatedly occupied fluvial landscapes, leveraging water sources and ecological focal points to mitigate risk. These findings suggest archaic humans possessed an ecological flexibility previously attributed only to later hominins. This adaptability likely facilitated the expansion of Homo erectus into the arid regions of Africa and Eurasia, redefining their role as ecological generalists thriving in some of the most challenging landscapes of the Middle Pleistocene.

The Last Ice Area-located to the north of Greenland and the northern Canadian Arctic Archipelago-is expected to persist as the central Arctic Ocean becomes seasonally ice-free within a few decades. Projections of the Last Ice Area, however, have come from relatively low resolution Global Climate Models that do not resolve sea ice export through the waterways of the Canadian Arctic Archipelago and Nares Strait. Here we revisit Last Ice Area projections using high-resolution numerical simulations from the Community Earth System Model, which resolves these narrow waterways. Under a high-end forcing scenario, the sea ice of the Last Ice Area thins and becomes more mobile, resulting in a large export southward. Under this potentially worst-case scenario, sea ice of the Last Ice Area could disappear a little more than one decade after the central Arctic Ocean has reached seasonally ice-free conditions. This loss would have profound impacts on ice-obligate species.

Permafrost thaw poses diverse risks to Arctic environments and livelihoods. Understanding the effects of permafrost thaw is vital for informed policymaking and adaptation efforts. Here, we present the consolidated findings of a risk analysis spanning four study regions: Longyearbyen (Svalbard, Norway), the Avannaata municipality (Greenland), the Beaufort Sea region and the Mackenzie River Delta (Canada) and the Bulunskiy District of the Sakha Republic (Russia). Local stakeholders' and scientists' perceptions shaped our understanding of the risks as dynamic, socionatural phenomena involving physical processes, key hazards, and societal consequences. Through an inter- and transdisciplinary risk analysis based on multidirectional knowledge exchanges and thematic network analysis, we identified five key hazards of permafrost thaw. These include infrastructure failure, disruption of mobility and supplies, decreased water quality, challenges for food security, and exposure to diseases and contaminants. The study's novelty resides in the comparative approach spanning different disciplines, environmental and societal contexts, and the transdisciplinary synthesis considering various risk perceptions.

Marine net primary production supports critical ecosystem services and the carbon cycle. However, the lack of consensus in the direction and magnitude of projected change in net primary production from models undermines efforts to assess climate impacts on marine ecosystems with confidence. Here we use contemporary remote sensing net primary production trends (1998-2023) from six remote sensing algorithms to discriminate amongst fifteen divergent model projections. A model ranking scheme, based on the similarity of linear responses of net primary production to changes in sea surface temperature, chlorophyll-a and the mixed layer, finds that future declines in net primary production are more likely than presently predicted. Even the best ranking models still underestimate the sensitivity of declines in net primary production to ocean warming, suggesting shortcomings remain. Reproducing this greater temperature sensitivity may lead to even larger declines in future net primary production than presently considered for impact assessment.

Permafrost is a considerable carbon reservoir harboring up to 1700 petagrams of carbon accumulated over millennia, which can be mobilized as permafrost thaws under global warming. Recent studies have highlighted that a fraction of this carbon can be transformed to atmospheric volatile organic compounds, which can affect the atmospheric oxidizing capacity and contribute to the formation of secondary organic aerosols. In this study, active layer soils from the seasonally unfrozen layer above the permafrost were collected from two distinct locations of the Greenlandic permafrost and incubated to explore their roles in the soil-atmosphere exchange of volatile organic compounds. Results show that these soils can actively function as sinks of these compounds, despite their different physiochemical properties. Upper active layer possessed relatively higher uptake capacities; factors including soil moisture, organic matter, and microbial biomass carbon were identified as the main factors correlating with the uptake rates. Additionally, uptake coefficients for several compounds were calculated for their potential use in future model development. Correlation analysis and the varying coefficients indicate that the sink was likely biotic. The development of a deeper active layer under climate change may enhance the sink capacity and reduce the net emissions of volatile organic compounds from permafrost thaw.

Climate warming has improved conditions for boreal forest growth, yet the region's fate as a carbon sink of aboveground biomass remains uncertain. Forest height is a powerful predictor of aboveground forest biomass, and access to spatially detailed height-age relationships could improve the understanding of carbon dynamics in this ecosystem. The capacity of land to grow trees, defined in forestry as site index, was estimated by analyzing recent measurements of canopy height against a chronosequence of forest stand age derived from the historical satellite record. Forest-height estimates were then subtracted from the predicted site index to estimate height-age growth potential across the region. Russia, which comprised 73% of the forest change domain, had strong departures from model expectation of 2.4-4.8 ± 3.8 m for the 75th and 90th percentiles. Combining satellite observations revealed a large young forest growth sink if allowed to recover from disturbance.

Climate change has negatively impacted grassland productivity in Africa. Climate-smart technologies such as forage grass, legume, and herb mixtures could enhance grassland productivity and resilience, offering a sustainable solution for African pasture-based livestock systems.

Understanding the behavior of large earthquakes over multiple seismic cycles is limited by short time spans of observations compared to recurrence intervals. Most of large instrumentally-recorded earthquakes have occurred on faults lacking well-documented histories of past events. The 2023 M_w 7.8-7.7 Kahramanmaraş earthquake doublet is exceptional as it ruptured multiple segments of the East Anatolian Fault (EAF) system, where historical records of devastating earthquakes span over two millennia. Here, we use historical earthquake records, measurements of interseismic deformation, and published slip models of the 2023 events to evaluate the recurrence patterns of large earthquakes. We compare slip deficit that accrued on each fault segment since the respective penultimate events to the average coseismic slip of the 2023 doublet. We find that the coseismic slip equaled to or exceeded the accumulated slip deficit, suggesting that the slip-predictable recurrence model applies as a lower bound on strain release during the Kahramanmaraş earthquakes.