Communications Earth & Environment最新文献

Despite their relative rarity, atmospheric rivers are key contributors to the surface mass balance of Antarctica. However, the future role of atmospheric rivers in modulating Antarctic sea-level contributions is a major area of uncertainty. Here, we leverage high-resolution climate simulations to show that Antarctic atmospheric rivers are highly sensitive to future increases in atmospheric moisture, leading to a doubling of atmospheric river frequencies and 2.5 × increase in precipitation from 2066-2100 under present-day thresholds for atmospheric river detection. However, future precipitation impacts are critically dependent on the detection threshold: accounting for moisture increases in the threshold produces smaller, regional changes in atmospheric river frequency, primarily resulting from an eastward shift in the polar jet maximum wind speeds. Our results underscore the importance of using large ensembles to quantify Antarctic atmospheric river responses to variability in projected moisture, which may not be captured when using only a few ensemble members.

The weathering and erosion of emerged land profoundly influences the Earth system, including the composition of the atmosphere and the type of nutrients delivered to the oceans. The emergence of land allowed for the formation of lakes and continental shelves, important habitats for the origin and evolution of life. Recent studies indicate a difference in silicon isotopes between Archean granitoids and their modern counterparts, which is explained by the incorporation of seawater-derived silica in the melting sources of the former. We show that this signature changed rapidly around 3.6 billion years ago, and that this shift is likely linked to an increase in the dissolved silicon flux from terrestrial weathering. Modeling suggests that the amount of oceanic silicon derived from terrigenous sources increased from near zero to around 32 ± 15% between 3.8 and 3.6 billion years ago. This indicates that, from this point onward, continental weathering feedbacks were established, and mass flux from land became an important source in the chemical budget of seawater, changes that likely exerted positive effects on the evolution of life.

Current frameworks for evaluating biogeochemical climate change feedbacks in Earth System Models lack an explicit consideration of nitrogen cycling in the land and ocean spheres despite its vital role in limiting primary productivity. As coupled carbon-nitrogen cycling becomes the norm, a better understanding of the role of nitrogen cycling is needed. Here we develop a new framework for quantifying carbon-nitrogen feedbacks in Earth System Models and show that rising nitrogen deposition acts as a negative feedback over both land and ocean, enhancing carbon dioxide (CO₂) fertilisation in a model ensemble. However, increased CO₂ uptake due to rising nitrogen deposition is small relative to the large reduction in CO₂ uptake when coupled carbon-nitrogen cycling is implemented in Earth System Models. Altogether, rising nitrogen deposition leads to only a minor increase in CO₂ uptake but also enhances nitrous oxide (N₂O) emissions over land and ocean, contributing only marginally to mitigating climate change.

The Western Antarctic Peninsula is undergoing rapid environmental change. Regional warming is causing increased glacial meltwater discharge, but the ecological impact of this meltwater over large spatiotemporal scales is not well understood. Here, we leverage 20 years of remote sensing data, reanalysis products, and field observations to assess the effects of sea surface glacial meltwater on phytoplankton biomass and highlight its importance as a key environmental driver for this region's productive ecosystem. We find a strong correlation between meltwater and phytoplankton chlorophyll-a across multiple time scales and datasets. We attribute this relationship to nutrient fertilization by glacial meltwater, with potential additional contribution from surface ocean stabilization associated with sea-ice presence. While high phytoplankton biomass typically follows prolonged winter sea-ice seasons and depends on the interplay between light and nutrient limitation, our results indicate that the positive effects of increased glacial meltwater on phytoplankton communities likely mitigate the negative impact of sea-ice loss in this region in recent years. Our findings underscore the critical need to consider glacial meltwater as a key ecological driver in polar coastal ecosystems.

Clay surfaces have been invoked as crucial components in the origin of life processes due to their ability to concentrate organics and abiotically catalyse (bio)polymer production. Still, the importance of the mutual nature of organo-clay interactions and the effects of off-world organics in this interplay is a largely unexplored realm. We demonstrate a previously unrecognised phenomenon that occurs upon the transient interaction of montmorillonite clay with the meteorite-common, non-proteinogenic γ-aminobutyric acid. Attenuated total reflectance Fourier transform infrared spectroscopy and X-ray diffraction show that an irreversible structural change is induced by the off-world species. A distinct partial clay exfoliation is correlated with the formation of nanoscale cavities in the mid-layers of the original structure, observable using transmission electron microscopy. This work demonstrates that an exogenous amino acid can alter clay and introduce 3D confined nano-environments, which may facilitate compartmentalisation in prebiotic times. Our findings also highlight new sustainable nanocomposite synthesis routes applicable in environmental/materials sciences.

Seasonal vertical migration of large lipid-rich copepods is often described as a mass descent of animals when primary production ceases, with important implications for mesopelagic food webs and global carbon sequestration. This view ignores the existence of surface-resident individuals, but here we show that non-migrants can form a substantial part of the populations of polar migrant species. In the Central Arctic Ocean, the biomass-dominant Calanus hyperboreus was evenly distributed throughout the water column from November 2019 to March 2020, with ~20% of subadults and adult females remaining in the upper 200 m and ~41% migrating to 1000-2000 m. These vertical positions aligned with differences in the copepods' cholesterol content, which can enhance the tissue density at higher temperatures. Gonad development and the vertical distribution of their offspring indicate that both non-migrant and migrant females contribute to the population recruitment. We reinterpret copepod seasonal migration as a bet-hedging strategy that balances nutritional benefits near the surface with survival benefits at depth, and thereby contributes to the species' resilience under climatic change.

Planktonic foraminifera are key contributors to the oceanic carbon cycle. In pelagic environments, carbonate production by planktonic biomineralizers regulates ocean-atmosphere carbon dioxide exchange and exports surface carbon to the deep ocean. Here we compare shell traits of three planktonic foraminifera species from the central Atlantic with a suite of environmental parameters to discern the factors underlying their variations. Our analysis revealed that calcification in foraminifera is associated with seawater density and depends on species habitat depth, whereas foraminifera bulk shell densities may serve as a seawater density proxy, regardless of species. We observe that their shell weights increased with habitat depth, enabling the living cells to adjust their overall density to match that of the surrounding liquid. This suggests that calcification in nonmotile organisms has a buoyancy regulatory function and will respond to the anthropogenically driven reductions in ocean density (oceanic rarefication), with potential consequences for the carbon cycle.

Fundamental ecological questions about the distribution of ocean life remain unanswered, hindering both the effective management of the ocean, and our comprehension of life on this planet. The benthic and pelagic realms are subject to different methods of study, and to understand where to best focus effort, a thorough understanding of existing information is required, allowing identification of critical knowledge gaps. Open-access data repositories provide a valuable means to identify such gaps; however, these repositories are subject to challenges in separating benthic from pelagic data. Here we demonstrate an automated data pipeline for extracting and separating benthic from pelagic data in open-access repositories. By stratifying data against essential ocean variables in a critical gap analysis, we show that large spatial and taxonomic biases exist in both the benthic and pelagic global datasets, favouring depths shallower than ~100 m, the northern hemisphere, and vertebrate species. The newly compiled, cleaned, and classified dataset is used to identify areas of chronic under sampling and high-priority regions for exploration. We argue that coordinated strategic prioritisation of sampling is needed to support modelling and prediction, enabling us to better manage our oceans and comprehend life on Earth.

With climate change-induced sea ice decline in the Arctic Ocean, nitrogen is expected to become an increasingly important determinant of primary productivity. Nitrogen fixation is the conversion of molecular nitrogen to bioavailable ammonium by microorganisms called diazotrophs. Here, we report nitrogen fixation rates, diazotroph composition, and expression under different stages of declining sea ice in the Central Arctic Ocean (multiyear ice, five stations) and the Eurasian Arctic (marginal ice zone, seven stations). Nitrogen fixation in the Central Arctic Ocean was positively correlated with primary production, ranging from 0.4 ± 0.1 to 2.5 ± 0.87 nmol N L^-1 d^-1. Along two transects across the marginal ice zone, nitrogen fixation varied between days and ice regime from below detection up to 5.3 ± 3.65 nmol N L^-1 d^-1 associated with an ice-edge phytoplankton bloom. We show nitrogen fixation in sea ice-covered waters of the Arctic Ocean and provide insight into present and active non-cyanobacterial diazotrophs in the region.

Wildfires are becoming one of the defining climate-related crises of the twenty-first century. We argue that their inclusion in the Loss & Damage framework of the United Nations Framework Convention on Climate Change is essential to support prevention, recovery and justice for the most affected communities.