Communications Earth & Environment最新文献

The surface and interior ocean are connected through physical processes that act in three dimensions and on subseasonal timescales. Numerical models and observations both highlight the importance of these eddying dynamics on shaping the biogeochemical and biological variability in the upper mesopelagic ocean. The resulting subsurface tracer variance outside of the photic zone has implications for ocean ventilation timescales as well as biogeochemical function and microbial community composition. Subsurface patchiness is best described using water mass frameworks that account for the dynamic processes that drive the transport of biogeochemical tracers between the photic zone and the mesopelagic. Investments in co-located and coincident measurements of physical and biological properties in the subsurface ocean will contribute to the growing understanding of mesopelagic biogeochemistry in the next decade.

Instability at volcanic edifices poses significant hazards, yet the processes driving rock weakening, particularly on steep, eroding flanks, remain poorly understood due to limited accessibility. Hydrothermal alteration is a key factor in weakening volcanic rocks, contributing to edifice destabilization and flank instability. La Fossa cone (Vulcano, Italy) provides an ideal setting for this study, with accessible hydrothermal alteration at the crater rim and similar alteration along inaccessible flanks that have a recent history of mass wasting. Here, we developed an integrated methodology combining drone photogrammetry with in situ Schmidt hammer testing to derive an empirical alteration-to-strength relationship for the crater rim and applied this knowledge to alteration sites on inaccessible flanks. An alteration map was generated using a Principal Component Analysis (PCA) to aid our classifications. This map was used to transpose over 1000 Schmidt hammer measurements (R-values ranging from 10.5 to 82), creating a thematic strength-alteration map. Results indicate a ~50% reduction in relative rock strength correlating with areas of degassing and hydrothermal activity, which coincides with past mass-wasting events. This integrated approach offers a transferable workflow for assessing volcanic slope instability, with direct applications to hazard monitoring and early warning systems.

In 2023, the United Nations High Commissioner for Refugees reported over 110 million displaced individuals globally, many in regions facing extreme weather and violence. Here we examine how these crises interact to shape household mobility in Bangladesh. Using data linking local conflict events, natural hazards, and household characteristics from 2011 to 2018, we apply machine learning models to capture complex, non-linear relationships between these risks. We find that combining conflict and hazard information improves predictions of household mobility. While exposure to violence or disasters increases mobility, households with remittances are more likely to move, whereas those with loans often remain. Interactions, such as between one-sided violence and landslides, further amplify movement, highlighting the importance of understanding how multiple stressors jointly influence household decisions.

Little is known about the structure of tropical forests despite its critical role in the provisioning of ecosystem services. Here we assess the vertical structure of forests in the Brazilian Amazon with a large-scale airborne LiDAR dataset. We show that fire has greater impact in the lowest forest strata, differently from selective logging and windthrow. We also find that secondary forests quickly recover or even exceed reference areas at the 1-10 m height stratum but that full recovery for the 20-30 m height stratum has not been achieved even after 35 years. Our modeling results suggest that proximity to roads, elevation, precipitation, soil pH, and proportion of sand in the soil are the most important predictors of forest structure. Finally, we identify 5 forest structural types (FSTs) and use them to visualize the spatial distribution of forest structure. This study provides important information for forest monitoring, management, and conservation.

Changes in atmospheric carbon dioxide concentrations, climate, and land management influence the abundance and distribution of C₃ and C₄ plants, yet their impact on the global carbon cycle remains uncertain. Here, we use a parsimonious model of C₃ and C₄ plant distribution, based on optimality principles, combined with a simplified representation of the global carbon cycle, to assess how shifts in plant abundances driven by carbon dioxide and climate affect global gross primary production, land carbon isotope discrimination, and the isotopic composition of atmospheric carbon dioxide. We estimate that the proportion of C₄ plants in total biomass declined from about 16% to 12% between 1982 and 2016, despite an increase in the abundance of C₄ crops. This decline reflects the reduced competitive advantage of C₄ photosynthesis in a carbon dioxide-enriched atmosphere. As a result, global gross primary production rose by approximately 16.5 ± 1.8 petagrams of carbon, and land carbon isotope discrimination increased by 0.017 ± 0.001‰ per year. Accounting for changes in C₃ and C₄ abundances reduces the difference between observed and modeled trends in atmospheric carbon isotope composition, but does not fully explain the observed decrease, pointing to additional, unaccounted drivers.

Coral tissue depth reflects organismal health and is influenced by environmental stressors. Reconstructing its past variability on inter- and intra-annual timescales, however, is not yet possible. Here we reconstructed seasonal tissue depth by measuring spatial offsets between growth cycles in corallite porosity and theca geochemistry (Lithium/Magnesium and Barium/Calcium ratios) of a single Siderastrea siderea core collected in Barbados. We show spatial offsets and thus tissue depth vary systematically over multiyear timescales, with decreasing values associated with thermal stress that impact extension rate and calcification in subsequent growth cycles. Large environmental disturbances such as the 2021 volcanic eruption of La Soufrière (St. Vincent) also impact tissue depth, in this case likely due to the release of bioactive metals upon ash deposition. This study investigates the robustness of the offset signal within a single colony and with further validation across multiple colonies could help reconstruct regional to global environmental and ecological stressors.

Marine Protected Areas (MPAs) are important tools in marine conservation. However, MPAs have unforeseen consequences, including complex adverse outcomes for human coastal communities through impacts such as dispossession of people to resource access. Here we searched the literature for evidence of MPA effects across the Sustainable Development Goals (SDGs), collected information on these effects and the forms of evidence used to document these effects. Our analysis indicated that MPAs can have both positive and negative effects across each of the 17 SDGs, and that many papers rely on secondary data over primary data to assess those effects. For SDGs 1 (End Poverty), 2 (No Hunger), and 5 (Gender Equality) we found that papers highlighting benefits of MPAs were usually more reliant on secondary information than papers emphasizing adverse impacts. Given the importance of local contexts, MPAs are better used as precision interventions rather than broad policy tools for achieving large-scale marine sustainability.

The outbreak of Highly Pathogenic Avian Influenza H5N1 in U.S. dairy cattle poses substantial risks to public health, economic sustainability of farming, and global food systems. Using a Computable General Equilibrium model, we simulate its short- to medium-term impacts on Gross Domestic Product and other macro-economic outcomes for the US and its main trading partners. We simulate impacts under the current situation and realistic and reasonable worst-case scenarios. We estimate domestic economic losses ranging between 0.06% and 0.9% of US GDP, with losses to the dairy sector ranging between 3.4% and 20.6%. Trading partners increase dairy production to compensate for the loss. Current government subsidies are about 1.2% (95% HDI: 1% to 1.4%) of output losses, and likely insufficient to incentivise farmers to step up surveillance and biosecurity for mitigating the possible emergence of H5N1 strains with pandemic potential into human populations.

Human-induced warming is amplified in the Arctic, but its causes and consequences are not precisely known. Here, we review scientific advances facilitated by the Polar Amplification Model Intercomparison Project. Surface heat flux changes and feedbacks triggered by sea-ice loss are critical to explain the magnitude and seasonality of Arctic amplification. Tropospheric responses to Arctic sea-ice loss that are robust across models and separable from internal variability have been revealed, including local warming and moistening, equatorward shifts of the jet stream and storm track in the North Atlantic, and fewer and milder cold extremes over North America. Whilst generally small compared to simulated internal variability, the response to Arctic sea-ice loss comprises a non-negligible contribution to projected climate change. For example, Arctic sea-ice loss is essential to explain projected North Atlantic jet trends and their uncertainty. Model diversity in the simulated responses has provided pathways to observationally constrain the real-world response.

Campi Flegrei last erupted in 1538 and periods of increased seismicity, gas emission and ground deformation occurred in the 50's, 70's 80's and are ongoing since 2005. The eventual culmination of the unrest in an eruption, would directly impact on 2 million people living in the region, making it of critical concern for scientists, authorities and the public. Here, we use existing data, thermal modelling and calculations of the physical properties of magma, to provide plausible future scenarios, under the assumption that magma injection at 4-5 km depth is responsible for the unrest episodes recorded since 1950. Our calculations suggest that a critically pressurised reservoir containing potentially eruptible magma is present today at ~ 4 km depth. However, a major impediment to eruption is the reservoir volume, which would need 2-3 decades to grow to the size of the one that fed the last eruption of Campi Flegrei in 1538.