Global Environmental Change Advances最新文献

In recent years, synthetic fuels have been identified as a potential measure for decarbonization of hard-to-abate sectors. Due to the high production costs associated with solar and wind power-based hydrogen production and carbon capture, previous research has indicated that the role of synthetic fuels may be restricted to specific sectors such as aviation. However, the high compatibility of these fuels with fossil fuel-based end-use technologies could support decarbonization while mitigating the risks associated with end-use technology transition, which has yet to be addressed in the literature. This study aims to quantify the role of synthetic fuels in the rapid end-use technology transition using an energy system model. To achieve this aim, we evaluated three indicators: the shares of electricity and hydrogen in final energy consumption, stranded investment, and the number of international energy transport vessels. The results suggest that synthetic fuel use can moderate the rapid transition to electricity and hydrogen utilization technologies, enabling decarbonization while avoiding the premature retirement of existing fossil fuel-based technologies. We conclude that the benefits of retaining fossil fuel-based end-use technologies must be weighed against the losses incurred due to the irrationality of using synthetic fuels over cheaper options.

Bird biodiversity in the United States is declining at alarming rates. Despite concerns about the link between climate change and the decline in bird biodiversity, there is limited understanding of the heterogeneous effects of climate change across species and regions and the extent to which these effects persist over time. Using a long-term dataset of the North American bird population from 1980 to 2015, we find statistically significant and robust evidence that an unconditional one-standard-deviation increase in the days above 25 °C (currently 7.8 days in a year but projected to exceed 28 days by the century’s end) decreases bird abundance and species richness by 2.5% and 1.7%, respectively; these effects are more pronounced for specialist birds (4.9% and 2.9%), long-distance migrant specialist species (5.2% and 3.2%), and bird populations in the drier areas, such as the West (7.0% and 2.5%). Additionally, we find no evidence of a diminishing impact of high temperatures on bird biodiversity over this period. Projecting forward to the end of this century, our models suggest that, depending on the extent of warming, the abundance and species richness of specialist birds could decline by 7%-16% and 4%-9%, respectively, relative to current levels. Though less pronounced, a statistically significant decline of 1–3% is also projected for generalist bird populations.

Potential changes in wildland fire regimes due to anthropogenic climate change can be projected using data from climate models, but directly applying these meteorological variables to long-term planning and adaptive management activities may be difficult for decision makers. Analog mapping, in contrast, creates more intuitive assessments of changing fire regimes that also recognize the complex, multivariate, and multi-scalar nature of ecosystems. Here, we use data from 20 downscaled climate models under two climate forcing scenarios, Representative Concentration Pathways (RCP 4.5 and 8.5), to identify and map future climate-fire analogs for 655 protected areas in the conterminous U.S. based on annual temperature, cumulative precipitation amount and seasonality, and fire regime potentials derived from a simple process-based fire frequency model. Patterns of analogs were heavily influenced by gradients in latitude and topography, with longer time frames (end-of-century conditions) and the more extreme climate forcing scenario resulting in greater analog distances and more ensemble entropy (i.e., less consensus among climate models regarding the closest analog for a given management unit). Finer scale analyses for three protected areas (Yellowstone and Great Smoky Mountains National Parks, White Mountain National Forest) illustrate how climate-fire analog mapping can improve insight into the types of ecosystem responses that might occur under similar management conditions. Federally protected areas such as national parks, forests, and wildlife refuges have long served as reference sites for the study of fire regimes, a role that is likely to continue because many of these units are managed to allow at least some ecosystem processes to operate independently. The results suggest that analog mapping approaches are well-suited as part of qualitative assessments within climate- and fire-aware adaptive management processes. The use of analogs to depict relatable, real-world depictions of possible ecosystem changes in a given place, can help managers make more strategic choices about when and where to resist, accept, or direct climate change-driven ecological change.

Human activities have significantly impacted natural habitats and wildlife worldwide, particularly emphasizing repercussions for freshwater habitats and associated species. These negative impacts on freshwater fish are well known, but for mammal species that regularly use and dependend on freshwater systems, there is an incomplete understanding. Here, we assessed the status of freshwater and semi-aquatic mammal species inhabiting and dependent on freshwater ecosystems (hereafter referred to as freshwater mammals) and evaluated the impact of human activities on species richness both globally and by biogeographical regions. We used structural equation modeling and simultaneous autoregressive models to assess the direct and indirect effects of seven anthropogenic-related variables on overall freshwater mammal richness. Specifically, we examined the effects of anthropogenic disturbance on the richness of threatened and non-threatened species, as well as species with decreasing and stable/increasing populations. Forty-three percent of all freshwater mammal species are classified as globally threatened by the IUCN Red List, with 50% experiencing population declines. Furthermore, 48% are affected by domestic or international trade, while 75% face threats from geographically expanding human activities. Aridity, pesticide pollution, human footprint, and croplands had the strongest negative effects on freshwater mammal richness. In contrast, the coverage of freshwater habitats (FWs), Indigenous Peoples' lands (IPLs), and protected areas (PAs) helped to sustain freshwater mammal species globally, with an even stronger positive effect at individual biogeographical regions. We conclude that FWs, IPLs, and PAs play a critical role in the conservation of freshwater mammal species, helping safeguard these species from extinction, however, freshwater ecosystems are seldom the focal point of conservation management strategies. The ongoing adverse anthropogenic impacts on these natural habitats present a potentially catastrophic and irreversible threat to global freshwater environments and the species, including humans, reliant upon them. We strongly advocate for the implementation of more robust national and international policy frameworks that endorse alternative and sustainable livelihoods. Such frameworks can play a crucial role in alleviating anthropogenic pressures, thereby aiding in the mitigation of the extinction risk faced by these vital ecosystems and the world's freshwater mammal species.