Aviation emissions contribute to climate change and local air pollution, with important contributions from non-CO2 emissions. These exhibit diverse impacts on atmospheric chemistry and radiative forcing (RF), varying with location, altitude, and time. Assessments of local mitigation strategies with global emission metrics may overlook this variability, but detailed studies of aviation emissions in areas smaller than continents are scarce. Integrating the AviTeam emission model and OsloCTM3, we quantify CO2, NOx, BC, OC, and SOx emissions, tropospheric concentration changes, RF, region-specific metrics, and assess alternative fuels for Norwegian domestic aviation. Mitigation potentials fora fuel switch to LH2 differ by up to 3.1 x 108 kgCO2-equivalents (GWP20) when using region-specific compared to global metrics. These differences result from a lower, region- specific contribution of non-CO2 emissions, particularly related to NOx. This study underscores the importance of accounting for non-CO2 variability in regional assessments, whether through region-specific metrics or advanced atmospheric modelling techniques.

Landslides induced by freeze-thaw processes on grasslands are one of the major geohazards, and their scale and frequency are increasing as the global warms. Freeze-thaw induced landslides degrade surface vegetation and soil properties, reduce biodiversity, intensify landscape fragmentation, and lead to losses in economy, human and animal lives. Despite substantial progress in research on landslides, there has been little study focused on how ground freeze-thaw events affect landslides. By critically analyzing previous studies, this paper proposes a conceptual framework for the forms and types, development, dominant factors, monitoring techniques, and impact mechanisms of freeze-thaw induced landslides. Landslides are controlled by soil characteristics and topographic slope, which are major intrinsic determinants. Increased rainfall, rising temperatures, and thickening active layer due to climate change are all direct drivers of freeze-thaw induced landslides. Vegetation conditions, animal behavior interference, and wind erosion all affect the occurrence and development process of landslides by modifying vegetation cover, soil physical and chemical properties, and structure. Currently, landslide monitoring techniques have evolved rapidly with improved efficiency and accuracy, but with only few applications for freeze-thaw induced landslides. There are a variety of prediction models for landslides, but few consider freeze-thaw effects and lack field validation. The new perspective on the occurring types and dominant factors enhances theoretical understanding of the formation mechanisms, which helps further monitor and analysis of freeze-thaw induced landslides. Future studies should concentrate on the coupling mechanism of multiple factors and the development of an accurate prediction system, which will greatly benefit the understanding and early detection of freeze-thaw induced landslides.

Research on mountain ecosystem services (MES) under the influence of climate change and human activities has gradually become the focus of academic attention in recent years. Here, this study analyzes the research hotspots and frontiers of this field based on metrics including main research forces, core journals and papers, research hotspots and topics by using the methods of bibliometrics and text mining. The results revealed the following: (1) the number of papers is increasing rapidly in recent years. From 2015 to 2019, 929 papers were published, with an average of 185 papers per year. But the average cited times of those papers is declining, dropped from 6.01 in 2016 to 4.2 in 2019. The USA, UK, and China rank the top three of the number of papers. Univ Maryland, Univ Oxford and Univ Wisconsin have the greatest influence, with an average of more than 77 citations per paper; (2) The most cited journals are PNAS, WETLANDS, ECOLOGY, AND SOCIETY, which are cited 191.54, 53.91, and 40.00 respectively. Most papers were published in OA journals including SUSTAINABILITY, WATER, Forests since 2017. Ten core papers undertaking knowledge transfer in this field have been identified; (3) analysis of the keywords found a new trend of integration of natural science and humanities. In two development stages of 2000-2014 and 2015-2019, the research hotspots mainly focused on mountain water resources, forest resources, land resources and the impact of climate change and human activities, and there are obvious differences and characteristics in different stages. The hotspot worthy of attention in the near future is the assessment of mountain ecosystem services capacity and value. This is the first comprehensive visualization and analysis of the research hotspots and trends of mountain ecosystem services.

The knowledge graph based on research papers can accurately identify and present the latest developments in scientific and technological (S&T) innovation and is of great significance for supporting strategic decision-making relating to S&T innovation in undeveloped areas. Based on the international research papers produced in Gansu Province during the 13th Five-Year Plan period (2016-2020), five metrics, including the number and characteristics of papers, co-authors, main publications and their fields, major supporting institutions, and main research areas, are established herein. The results indicate that: (i) the total of 29,951 papers were published, which is about 2.89 times that in 2010-2015; (ii) Gansu Province collaborated with 149 countries/regions globally; (iii) the top 5 journals in terms of the number of papers were Medicine, Scientific Reports, RSC Advances, Science of the Total Environment, and Physical Reviews D; (iv) the funding sources were mainly from the national level; and (5) the top 5 research areas were chemistry, engineering, physics, material science, environmental science, and ecology, which accounted for 64.7% of all papers. Finally, the present study puts forward some recommendations for the decision-making process in the strategic layout of S&T innovation in Gansu Province.

Remote sensing, as a crucial method to obtain information on water environmental processes, has become a major source of data, particularly of water environment and water resources, which are sensitive to global climate change. The bibliometric analysis provided here shows the research characteristics and developments of remote sensing-based observations of water environmental processes under a changing climate from 2000 to 2018. Visualized knowledge mapping is introduced to investigate the development status, scientific collaboration, involved disciplines, research hotspots and emerging trends of this field. The breadth and depth of remote sensing application in water environmental process studies have improved significantly as the number of related publications rose at an average annual growth rate of 15.97% in the 21st century. The United States and China were the leading contributors with the largest number of publications and all of the top 15 most active institutions. In addition, this field is a highly interdisciplinary field that covers a wide range of interests, from water resources to environmental science, geology, engineering, ecology, and agriculture. The application of remote sensing technology has significantly promoted the estimation of evapotranspiration and soil moisture, thereby offering a more complete perspective to the understanding of the water cycle. Additionally, climate change and its complex interactions with water environmental processes, including the occurrence of drought events, are of great significance and require special attention.

High-latitude regions are experiencing rapid and extensive changes in ecosystem composition and function as the result of increases in average air temperature. Increasing air temperatures have led to widespread thawing and degradation of permafrost which in turn has affected ecosystems, socioeconomics, and the carbon cycle of high latitudes. Here we overcome complex interactions among surface and subsurface conditions to map near-surface permafrost through decision and regression tree approaches that statistically and spatially extend field observations using remotely sensed imagery, climatic data, and thematic maps of a wide range of surface and subsurface biophysical characteristics. The data fusion approach generated medium-resolution (30-m pixels) maps of near-surface (within 1 m) permafrost, active-layer thickness, and associated uncertainty estimates throughout mainland Alaska. Our calibrated models (overall test accuracy of similar to 85%) were used to quantify changes in permafrost distribution under varying future climate scenarios assuming no other changes in biophysical factors. Models indicate that near-surface permafrost underlies 38% of mainland Alaska and that near-surface permafrost will disappear on 16 to 24% of the landscape by the end of the 21st Century. Simulations suggest that near-surface permafrost degradation is more probable in central regions of Alaska than more northerly regions. Taken together, these results have obvious implications for potential remobilization of frozen soil carbon pools under warmer temperatures. Additionally, warmer and drier conditions may increase fire activity and severity, which may exacerbate rates of permafrost thaw and carbon remobilization relative to climate alone. The mapping of permafrost distribution across Alaska is important for land-use planning, environmental assessments, and a wide-array of geophysical studies. (C) 2015 Elsevier Inc. All rights reserved.

Environmental impact studies of forest bioenergy systems usually account for CO2 emissions and removals and identify the so-called carbon debt of bioenergy through comparison with a reference system. This approach is based on a simple sum of fluxes and does not consider any direct physical impact or climate system response. Other recent applications go one step further and elaborate impulse response functions (IRFs) and subsequent metrics for biogenic CO2 emissions that are compatible with the life-cycle assessment (LCA) methodology. However, a thorough discussion about the role of the different metrics in the interpretation of the climate impacts of forest bioenergy systems is still missing. In this work, we assess a single LCA dataset of selected bioenergy systems using different emission metrics based on cumulative CO2 emissions, radiative forcing and global surface temperature. We consider both absolute and normalized metrics for single pulses and sustained emissions. The key challenges are the choice of end point (emissions, concentration, radiative forcing, change in temperature, etc), the type of measure (instantaneous or time-integrated) and the treatment of time. Bioenergy systems usually perform better than fossil counterparts if assessed with instantaneous metrics, including global surface temperature change, and in some cases can give a net global cooling effect in the short term. The analysis of sustained, or continuous emissions, also shows that impacts from bioenergy systems are generally reversible, while those from fossil fuels are permanent. As shown in this study, the metric choice can have a large influence on the results. The dominant role traditionally assigned to cumulative metrics in LCA studies and climate impact accounting schemes should therefore be reconsidered, because such metrics can fail to capture important time dependences unique to the biomass system under analysis (to which instantaneous metrics are well suited).

The development of potential metrics for comparing black carbon (BC) to carbon dioxide has been requested within legislation in the United States and has been discussed at the United Nations Framework Convention on Climate Change Conference of the Parties in Poznan: therefore, it is important to further investigate the advantages and drawbacks to using such a metric. For context, we summarize the various proposed CO2 equivalent metrics and the rationales for developing them. We use BC marginal abatement curves to examine the implications of using 100-year global warming potentials to include BC in greenhouse gas (GHG) trading regimes. This idealized study demonstrates the impacts on emissions of CO2, and radiative forcing over time. Finally, we address the drawbacks of trading poorly quantified short-lived emissions with GHGs despite different physical interactions with the climate system. While the case for reducing BC for both health and climate benefits is compelling, there are reasons for limiting the use of BC metrics to illustrative analyses, such as identifying which BC mitigation actions would provide the greatest climate benefits, rather than using these metrics for trading with GHGs. Indeed, market-based mechanisms in general may not be appropriate for BC regulation at this time.