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Effective selection of climate predictors is a fundamental aspect of climate modeling research. Predictor Screening (PS) plays a crucial role in identifying regional climate drivers, reducing noise, expediting convergence, and minimizing time consumption, ultimately leading to the development of robust models. This review delves into the complex landscape of PS techniques within the context of Numerical Climate Modeling (NCM), with a specific focus on their applicability across various Köppen climate classifications and PS model structures. The analysis revealed substantial variations in the performance of PS methods, shedding light on their ability to capture –and prioritize predictors related to precipitation and temperature within distinct climate contexts. Furthermore, the provided methods have been categorized into two subsections: Feature Selection (FS) and Feature Extraction (FE), with FS encompassing filter, wrapper, embedded, and ensemble/hybrid techniques, and FE covering Linear Feature Extraction (LFE), Time-Domain Analysis (TDA), deep learning, and clustering methods. The initial compilation of papers, acquired through a keyword search on Scopus, consisted of 3650 documents. Following a meticulous evaluation process, 206 papers were identified as fitting for inclusion in the literature review, covering the time frame from 1974 to November 3, 2023. In conclusion, the results provide a detailed understanding of the strengths and limitations of each approach, establishing a hierarchy of effectiveness contingent upon the specific climate context. Additionally, insights into promising avenues for future research in this field are offered. This review follows the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) standard as its foundation. [ABSTRACT FROM AUTHOR]

Desertification in karst is an effect of climate change and not sustainable anthropogenic activities, the combination of which, however, causes the gradual loss of karst natural resources, such as soil, vegetation, and groundwater. A considerable percentage of global karst areas is found in drylands, characterized by negative water balance and scarce presence of soils. High fragility of the karst environment, and its vulnerability to land degradation and pollution because of the peculiar anisotropic setting, environmental dynamics, and of the direct connection between the surface and the subsurface, are at the origin of the severe problems deriving from desertification processes in karst. In addition to natural drivers, such as geology and topography, karst desertification is generally due to four main factors, mostly or partly related to human activity: deforestation, improper land use, groundwater overexploitation, and climate changes. Through the analysis of a collection of studies conducted in several karst territories around the world, the present paper aims to provide an overview of the processes leading to desertification risks in karst areas. Emphasizing the need to preserve these fragile environments, characterized by peculiar features and precious freshwater resources, this review summarizes the main situations at the global scale of rocky desertification in karst, at the same time providing indications for developing innovative and multi-disciplinary approaches addressed toward mitigation of the risk related to desertification in karst. [ABSTRACT FROM AUTHOR]

Water erosion, a notorious major threat to food security and ecosystem sustainability, is strongly conditioned by spatial and temporal scale effects. This paper systematically reviews the scale issues in runoff and sediment delivery (SIRSD) as a research field by integrating the traditional review approach and bibliometric analysis. This review summarises SIRSD's roots and the scale effect on runoff and sediment delivery. Then, we provide quantitative insights into the SIRSD domain's development history, thematic structure, geographic distribution, international cooperation, and methodologies. Findings show that: i) SIRSD arises from the gap between the non-linearity of runoff and sediment delivery across scales and our ability to measure it. Point-based and short-term measurements cannot capture the non-linearities from the spatio-temporal heterogeneities and cross-scale interactions of factors or processes. ii) Previous literature provides evidence that the spatial scaling of specific runoff (r), soil erosion (SE), sediment yield (SSY), or sediment delivery ratio (SDR) with drainage area (A) or slope length (L) exhibits contrasting patterns due to distinct mechanisms. Infiltration-excess and saturation-excess processes account for inverse and positive r - A relations, respectively. Interrill-erosion and rill-erosion cause inverse and positive SE-L relations. Hillslope-erosion and channel/bank-erosion explain inverse and positive SSY-A relations. Downstream increasing deposition and additional sediment inputs drive inverse and positive SDR-A relations. These scaling relationships can be nonlinear or complex due to spatial heterogeneities in land use, vegetation, topography, climate, lithology, and soil characteristics. Hence, applying an empirical scaling equation developed from the region with distinct environmental contexts is not recommended. Furthermore, the existing scaling patterns or equations may require updating given global climate and land use change. iii) SIRSD is a complex and multidisciplinary issue investigated by scientists from 93 countries since 1928. International research has substantially facilitated the understanding of SIRSD; still, more collaboration should focus on less-developed countries with high soil and water loss risks and urgent conservation needs, such as those in Africa and South America under cropland expansion. iv) Scale mismatch and scale break have discredited large-scale erosion and sediment assessments. Incorporating gully and bank erosion into modelling, extending the scale range of the L factor, and expanding the sediment scaling scope from watershed to slope may make a difference. Therefore, more research with nested design incorporating multiple scales is necessary for cross-scale analysis and scalable modelling. Addressing global climate change requires improving real-time urban flood forecasting and integrating downscaled climate models with hydrology, erosion, and sediment transport models. • A bibliometric review of the global SIRSD research for the first time. • SIRSD is rooted in the gap between natural nonlinearity and our measuring ability. • Scaling of specific runoff, erosion, sediment yield, and SDR has diverse patterns. • Scale mismatch and scale break discredit large-scale modelling and assessments. [ABSTRACT FROM AUTHOR]

Radon can pose a serious risk on human health. At present, radon has been considered as the second leading cause of lung cancer after smoking. The potential risk of radon exposure in cold regions of Northern Hemisphere is increasing due to climate-induced permafrost degradation. In this paper, we took permafrost regions in the Northern Hemisphere as our study area. We performed an extensive literature review on the Web of Science (WoS), China National Knowledge Infrastructure (CNKI), and Google Scholar (GS). We divided these selected literatures into three groups: Group uranium, Group radon and Group permafrost and tried to reveal the impacts of distribution of uranium deposits/u-rich rocks and permafrost/permafrost degradation on radon concentration/migration in permafrost regions. Based our research, it is evident that uranium deposits or U-rich rocks provides an abundant source of U (Ra) for soils and groundwaters in permafrost regions, resulting in abnormally high concentrations of radioactive elements in soils and groundwaters. As a natural barrier, permafrost soils could screen the radon gas from migrating into underground dwellings and work-space in cold regions. However, permafrost degradation has been extensively observed and this trend is projected to continue under a warming climate. Permafrost degradation and ground ice melting, water exchange, gas emissions and thaw settlement have enhanced the ability of radon migration into dwellings and work space, which substantially endangers human health if long exposed. Our synthesis results also underline that the related research of radon migration and relation in permafrost regions are grossly inadequate and urgently needed. Research priorities include the mechanisms of radon migration in freezing, frozen, thawing and thawed soils/rocks, responses of release of radon sequestered in permafrost soils and radon migration in groundwater systems, among many others, to permafrost degradation. [ABSTRACT FROM AUTHOR]

Soil erosion is part of the erosion-sedimentation cycle and a type of land degradation that can be caused by poor land management. This is expected to be exacerbated by climate change. The rainfall erosivity factor (R) of the Universal Soil Loss Equation (USLE) family of soil erosion models is one of the most important parameters being studied because it is heavily influenced by climate change. The determination of the R factor necessitates high-frequency precipitation data, which are unavailable for a significant portion of the globe. For decades, researchers in data-sparse regions have estimated the R factor using empirical equations that required only monthly or annual rainfall data. Unfortunately, many of these equations are outdated and susceptible to misuse. This study presents an empirical R equation based on the Modified Fournier Index (MFI) that has caused probably one of the most widespread and unnoticed errors in soil erosion research for at least 33 years. Our exhaustive literature search and analysis uncovered 125 papers with 28 incorrect R equation formulations. We discovered that the earliest incorrect publication dates back to 1989, and most of the studies were conducted in Asia (China and India). The 125 published papers have similar citation characteristics (three citations per year per paper) as other papers in the field of soil erosion modelling, and many of the 125 papers were published in well-known scientific journals. Together, they have been cited over 3300 times by international researchers. In addition, the number of incorrect papers has increased dramatically over the past few years (2015–2021), indicating that the equation is spreading more frequently than the general publication trend. Since using an incorrect R equation can result in a significant bias in estimating the R factor and, consequently, soil erosion, the incorrect use could significantly bias numerous studies. The inaccuracy also hinders global efforts like the "Global Applications of Soil Erosion Modelling Tracker (GASEMT)" to synthesize soil erosion studies worldwide to shed light on the global problem of soil erosion and to promote environmental education. Consequently, the primary objective of this paper is to contribute to the recognition of the use of incorrect R equations, thereby reducing or even preventing their further spread and thus limiting the number of studies publishing biased results. [ABSTRACT FROM AUTHOR]

This paper discusses the potential response of fluvial processes and landforms to the projected permafrost degradation and related hydrological change. Fluvial system structure is presented in the first section of the paper along with permafrost controls over its functioning, which vary across fluvial system compartments. The distinction is drawn between primarily fluvial landforms that are expected to adjust to future hydrology with less permafrost constraints, and primarily cryogenic landforms evolving in line with permafrost disturbances. The influence of permafrost on fluvial action varies across compartments: on hillslopes, permafrost mostly controls the occurrence of surface runoff, in river valleys and channels, sediment erodibility, while thermal interaction is essential for growing thermo-erosional gullies. Observed and projected changes in permafrost and hydrology are outlined, and their relevance for cryo-fluvial evolution of fluvial systems is reviewed. Based on these projections, future changes in fluvial action in each compartment are discussed. On hillslopes, where permafrost exerts important controls on hillslope hydrology, fluvial activity of overland flow is expected to decrease following the active layer deepening and decreased overland flow duration. In erosional networks, controlled by thermal interaction between runoff and permafrost terrain, higher water temperature is expected to increase the occurrence and rates of thermo-erosional gully development. In river valleys and channels, where permafrost controls the erodibility of bed and bank material, the expected fluvial feedbacks vary across scales and stream orders, and include changes in seasonality of channel deformations, increased retreat rates in lower river banks and decreased, in higher banks, along with floodplain subsidence, and minor potential for complete destabilization of existing channel patterns. Future collateral effects of fluvial change include alterations of terrestrial biogeochemical cycles and societal impact that must be accounted for in climate change adaptation and mitigation strategies. [ABSTRACT FROM AUTHOR]

Known as the "third pole" and "water tower of Asia", the Tibetan Plateau (TP) is the home to the largest number of glaciers in the mid-latitudes and one of the most sensitive areas to global climate change due to its special geographical location and powerful thermodynamic effects. In recent years, the TP has been affected by exogenous pollutants and the concentrations of some pollutants have shown an increasing trend, especially light-absorbing aerosols (LAAs), when ice core records, ground- and aircraft-based field campaigns and satellite technology enabled synthesized monitoring. The enhanced warming of the vast majority of regions in TP, together with Arctic warming, and snow/ice decline, represents credible evidence of anthropogenic climate change. This paper provides a comprehensive review of studies on the sources, characteristics and climate impacts of LAAs over the TP. Adjacent to the two major emission sources of LAAs in East Asia and South Asia, the unique geographical location and climatic characteristics of the TP make it possible for TP LAAs to cause atmospheric warming and accelerated glacier melting, affecting the hydrological cycle in South Asia, East Asia and even the Northern Hemisphere, thus causing a series of serious environmental and social problems. LAAs, such as black carbon and dust, can strongly absorb solar radiation and and have significantly influence on climate change. Moreover, light-absorbing impurities (LAIs) on snow/ice can reduce the snow/ice albedo and further accelerate the snow/ice melting. Both LAAs and LAIs over the TP can induce thermodynamic feedback processes, cause significant warming of the TP and then lead to a strengthening of the early monsoon and affect the subsequent evolution of the monsoon. Many mechanisms have been proposed forth regarding how TP LAAs modulate the phase, intensity, and amplitude of the Asian climate system. A wide range of theoretical, observational, and modeling findings on TP LAAs and their climate impacts are synthesized, in which dust aerosols from drylands and black carbon from biomass burning are considered leading components. By coupling an integrated approach with state-of-the-art modeling, high temporal and fine spatial resolution remote sensing observations with increasing sampling over the TP will provide further insights into TP aerosols. • Light-absorbing aerosols warm the Tibetan Plateau, further influence climate system • The external input of light-absorbing aerosols over the Tibetan Plateau is dominant • Climate effects of light-absorbing aerosols or impurities in snow is divergent [ABSTRACT FROM AUTHOR]

Mt. Everest (Qomolangma or Sagarmatha), the highest mount on Earth and located in the central Himalayas between China and Nepal, is characterized by highly concentrated glaciers and diverse landscapes, and is considered to be one of the most sensitive area to climate change. In this paper, we comprehensively synthesized the climate and environmental changes in the Mt. Everest region, including changes in air temperature, precipitation, glaciers and glacial lakes, atmospheric environment, river and lake water quality, and vegetation phenology. Historical temperature reconstruction from ice cores and tree rings revealed the distinct features of 20th century warming in the Mt. Everest region. Meteorological observations further proved that the Mt. Everest region has been experiencing significant warming (approximately 0.33 °C/decade) but relatively stable precipitation during 1961−2018 AD. Projected results (during 2006−2099 AD) under different representative concentration pathway scenarios showed a general warming trend in the region, with larger warming occurring in winter than in summer. Meanwhile, the precipitation projections varied spatially with no significant trends over the region. Intensive glacier shrinkage was characterized by decreasing glacier areas, while glacier-fed river runoff increased. Glacial lakes expanded with increasing glacial lake areas and numbers. These findings indicated a clear regional hydrological response to climate warming. Owing to the remote location of Mt. Everest, the present atmospheric environment remained relatively clean; however, long-range transport of atmospheric pollutants from South Asia and West Asia may have substantially influenced the Mt. Everest region, resulting in increasing concentrations of pollutants since the Industrial Revolution. Anthropogenic activities have been shown to influence river and lake water quality in this remote region, especially in the downstream. The end of the vegetation growing season advanced in the northern slope and did not change in southern slope region of the Mt. Everest, and there was no significant change in start date of the growing season in the region. This review will enhance our understanding of climate and environmental changes in the Mt. Everest region under global warming. • Climate and environmental changes were synthesized in the Mt. Everest region. • Glaciers have retreated significantly, posing impacts to river runoff and glacial lakes. • Transboundary transport of atmospheric pollutants influenced the region. • TThere was no significant change in start date of the growing season. [ABSTRACT FROM AUTHOR]

The Early 20th Century Warming (ETCW) in the northern high latitudes was comparable in magnitude to the present-day warming yet occurred at a time when the growth in atmospheric greenhouse gases was rising significantly less than in the last 40 years. The causes of ETCW remain a matter of debate. The key issue is to assess the contribution of internal variability and external natural and human impacts to this climate anomaly. This paper provides an overview of plausible mechanisms related to the early warming period that involve different factors of internal climate variability and external forcing. Based on the vast variety of related studies, it is difficult to attribute ETCW in the Arctic to any of major internal variability mechanisms or external forcings alone. Most likely it was caused by a combined effect of long-term natural climate variations in the North Atlantic and North Pacific with a contribution of the natural radiative forcing related to the reduced volcanic activity and variations of solar activity as well as growing greenhouse gases concentration in the atmosphere due to anthropogenic emissions. [ABSTRACT FROM AUTHOR]