Communications Earth & Environment最新文献

The extinction of woody vegetation in Antarctica remains difficult to constrain due to its fragmented macrofossil record. Despite its long-standing polar position, Antarctica hosted extensive vegetation throughout the Paleogene. This changed near the Eocene-Oligocene Transition (ca. 34 Ma) as glaciation led to vegetation decline. Sparse evidence suggests tundra-like forests persisted until the Pliocene in East Antarctica, but the Neogene record from West Antarctica is largely restricted to palynoflora data. Here, we report early Miocene plant macrofossils from West Antarctica, consisting of Nothofagus leaves. U-Pb zircon geochronology confirms tundra-like vegetation existed in this region during the early Miocene (ca. 22-20 Ma), representing the youngest macrofossil record of West Antarctica. These findings suggest that Nothofagus either persisted through Antarctica's harsh Late Cenozoic Ice Age conditions or recolonised during intermittent warm periods. This substantially advances our understanding of West Antarctica's vegetation history and extends the known record of Nothofagus in Antarctic ecosystems.

Projecting future climate change is important for implementing the 2015 Paris Agreement, which aims to limit greenhouse gas emissions to a level that would keep the global average temperature increase to 2100 below 2 °C. The Intergovernmental Panel on Climate Change uses emissions scenarios for projecting climate change, but since 2017, an alternative fully statistical Bayesian probabilistic approach has been developed. Both approaches rely on an equation that expresses emissions as the product of population, Gross Domestic Product (GDP) per capita, and carbon intensity, namely carbon emissions per unit of GDP. Here, we use data on these quantities for 2015-2024 to probabilistically assess the changes in climate change prospects associated with post-Paris emissions. These show that carbon intensity declined (i.e., improved) substantially over that period, but that overall carbon emissions rose, due to the rapid rise in world GDP, which more than canceled out the progress made. We found that the projected temperature increase to 2100 declined only slightly, from 2.6° C to 2.4 °C. Meanwhile, the chance of staying below 2 °C remained low, at 17%. However, the chance of the most catastrophic climate change, above 3 °C, has gone down substantially, from 26% to 9%.

Altered fire regimes are a global challenge, increasingly exacerbated by climate change, which modifies fire weather and prolongs fire seasons. These changing conditions heighten the vulnerability of ecosystems and human populations to the impacts of wildfires on the environment, society, and the economy. The rapid pace of these changes exposes significant gaps in knowledge, tools, technology, and governance structures needed to adopt informed, holistic approaches to fire management that address both current and future challenges. Integrated Fire Management is an approach that combines fire prevention, response, and recovery while integrating ecological, socio-economic, and cultural factors into management strategies. However, Integrated Fire Management remains highly context-dependent, encompassing a wide array of fire management practices with varying degrees of ecological and societal integration. This review explores Integrated Fire Management as both an adaptation and mitigation strategy for altered fire regimes. It provides an overview of the progress and challenges associated with implementing Integrated Fire Management across different regions worldwide. The review also proposes five core objectives and outlines a roadmap of incremental steps for advancing Integrated Fire Management as a strategy to adapt to ongoing and future changes in fire regimes, thereby maximizing its potential to benefit both people and nature.

Giant magnetofossils are unusual, micron-sized biogenic magnetite particles found in sediments dating back at least 97 million years. Their distinctive morphologies are the product of biologically controlled mineralisation, yet the identity of their biomineralising organism, and the biological function they serve, remain a mystery. It is currently thought that the organism exploited magnetite's mechanical properties for protection. Here we explore an alternative hypothesis, that it exploited magnetite's magnetic properties for the purpose of magnetoreception. We present a three-dimensional magnetic vector tomography study of a giant magnetofossil and assess its magnetoreceptive potential. Our results reveal a single magnetic vortex that displays an optimised response to spatial variations in the intensity of Earth's magnetic field. This magnetic trait may have conferred an evolutionary advantage to mobile marine organisms, providing an upper age limit on the development of navigational magnetoreception and raising the possibility that earlier evidence of this sense may yet be preserved in the fossil record. More broadly, this work provides a blueprint for assessing the morphological and magnetic evidence for putative biogenic iron oxide particles, which are a key component in the search for early life on Earth and Mars.

Geochemical traces of past environments are preserved in the geological record. Although secondary processes often erase this information, fluid inclusions in hydrothermal minerals act as time capsules for reconstructing the evolution of Earth's atmosphere and oceans, including the Great Oxidation Event (GOE). Here, we summarize decades of insights from analyses of ancient fluids in hydrothermal minerals worldwide. These geochemical constraints illuminate the formation of the atmosphere, its evolution through volcanism, escape to space, and subduction. Reconstructions of past atmospheric noble gas and nitrogen compositions, along with ocean salinity, reveal major steps in our planet's evolution. They shed unique light on long-standing questions, including Earth's climate under a faint young Sun, the missing Xe paradox, the cause and timing of oxygenation, the emergence of continents, and the flourishing of life. A refined understanding of the physical mechanisms driving xenon isotopic evolution prior to the GOE may further constrain links between early solar activity and early environmental changes.

The extreme geochemical enrichment of post-collisional potassium-rich lava in the Alpine-Himalayan orogenic belt has led researchers to hypothesize that enrichment is inherited from a metasomatized mantle source potentially incorporating crustal components. However, direct verification of metasomatic processes remains challenging due to the scarcity of mantle rocks preserving metasomatism records. Here, we report two groups of mantle xenolith entrained in Tibetan ultrapotassic lavas. Integrated petrographic observations, whole-rock geochemistry, and in-situ microanalysis reveal that subcontinental lithospheric mantle exhibits extreme enrichment in both isotopes and incompatible elements. Textural evidence of vein networks and melt pockets in xenoliths indicate the coexistence of carbonate and silicate metasomatic regimes. Considering subduction-collision background, we propose that the recycling of Indian continental materials during collision substantially contributes to the metasomatic enrichment of the Tibetan subcontinental lithospheric mantle.

Climate change is resulting in more extreme fire weather during major heatwaves. Across temperate Europe, shrub landscapes dominate the area burned, with the moisture content of fuels during these events determining the threat posed. Current controls on the moisture content of temperate fuel constituents and their response to future extreme heatwaves are not known. We took field measurements of live and dead heather (Calluna vulgaris) and organic soil moisture content across the UK over 3 years, including an intensive sampling campaign during the July 2022 heatwave. Here, we show that the fuel moisture content of live fuel is associated significantly with phenological variables, dead fuel only with weather variables, whilst organic-rich ground fuels are more associated with landscape variables. However, during the record 2022 heatwave there was a harmonisation in fuel moisture controls across different fuel constituents, with those controls being driven by weather alone. This caused synchronised extreme dryness outside of current seasonal norms across all fuel constituents at the same time and place. Future intense summer heatwaves can therefore be expected to align the most severe conditions for fire ignition, spread and impact in traditionally non-fire prone regions, producing humid temperate landscapes susceptible to extreme wildfire events.

Lead has been central to technological development for centuries; however, its release into the environment and subsequent human exposure pose significant public health risks. The review presented here critically assesses the contemporary environmental lead risk as global lead production and use are rapidly increasing, largely driven by the rising demand for electrification. We show that environmental lead exposure persists today due to legacy contamination, ongoing coal usage, and insufficient protection of workforces during production, use, and recycling of lead-acid batteries and other lead-containing products, particularly in low- and middle- income countries. We estimate that contemporary childhood lead exposure alone leads to an annual global economic loss exceeding $3.4 trillion (2021 US dollars adjusted for purchasing power parity), with pronounced disparities between high- and low- and middle- income countries. To prevent a large-scale resurgence in lead exposure, we identify four critical areas for urgent policy intervention.

The Nile Basin, a freshwater resource for over 300 million people, faces unprecedented hydrological risks under climate change and transboundary water disputes. Yet, basin-wide projections of extreme streamflow events remain limited by fragmented modeling and insufficient integration of climate uncertainty. Here, we assess future flood risk in downstream countries using a calibrated, climate-driven Soil and Water Assessment Tool model, forced by bias-corrected CMIP6 models under the SSP2-4.5 and SSP5-8.5 scenarios, marking the first application of its kind targeting the Nile Basin downstream regions. Our results indicate a 63% (SSP2-4.5) and 85% (SSP5-8.5) increase in 100-year peak discharges in the 21st century, with extreme floods occurring nearly every decade under high-emission scenarios. Our climate-driven hydrologic modeling, risk analysis, and climate projections emphasize the need for coordinated planning, provide actionable risk information, and a framework for regional cooperation and preparedness to mitigate future flood risks and address water security challenges in the Nile Basin.

Marine calcifiers support ecosystem services, including shell fisheries and coral reefs. Constraining the saturation state of the calcification media of these organisms is essential to understand the response of biomineralisation to environmental change. Here we synthesise aragonite over variable pH, saturation state, temperature, and in the presence of simple biomolecules. We show that the lithium/magnesium distribution coefficient, relating aragonite and precipitation fluid compositions, is significantly affected by precipitation rate but not by temperature or pH. Precipitation rate reflects saturation state and temperature, so lithium/magnesium of biogenic aragonite can be used to calculate mineral precipitation rate and, if the precipitation temperature is known, to reconstruct calcification medium saturation state. Applying the distribution coefficients to a published calcifier dataset indicates that calcification media saturation state is ca. 9 to 13 at 18-30 °C and ca. 6 to 10 at 10-18 °C. Coral calcification media saturation state varies between ocean sites, species, and reef zones.