Substituting alternative materials and energy sources with forest biomass can cause significant environmental consequences, such as alteration in the released emissions which can be described by displacement factors (DFs). Until now, DFs of wood-based materials have included greenhouse gas (GHG) emissions and have been associated with lower fossil and process-based emissions than non-wood counterparts. In addition to GHGs, aerosols released in combustion processes, for example, alter radiative forcing in the atmosphere and consequently have an influence on climate. In this study, the objective was to quantify the changes in the most important aerosol emission components for cases when wood-based materials and energy were used to replace the production of high-density polyethylene (HDPE) plastic, common fossil-based construction materials (concrete, steel and brick), non-wood textile materials and energy produced by fossil fuels and peat. For this reason, we expanded the DF calculations to include aerosol emissions of total suspended particles (TSP), respirable particulate matter (PM10), fine particles (PM2.5), black carbon (BC), nitrogen oxides (NOx), sulphur dioxide (SO2) and non-methane volatile organic compounds (NMVOCs) based on the embodied energies of materials and energy sources. The DFs for cardboard implied a decrease in BC, SO2 and NMVOC emissions but an increase in the other emission components. DFs for sawn wood mainly indicated higher emissions of both particles and gaseous emissions compared to non-wood counterparts. DFs for wood-based textiles demonstrated increased particle emissions and reduced gaseous emissions. DFs for energy biomass mainly implied an increase in emissions, especially if biomass was combusted in small-scale appliances. Our main conclusion highlights the critical need to thoroughly assess how using forest biomass affects aerosol emissions. This improved understanding of the aerosol emissions of the forestry sector is crucial for a comprehensive evaluation of the climate and health implications associated with forest biomass use.

Light-absorbing organic carbon (i.e., brown carbon, BrC) significantly contributes to light absorption and radiative forcing in the atmospheric particles. However, the secondary formation of BrC and optical properties of secondary BrC are poorly understood. In this study, we analyzed and evaluated the light absorption and environmental effects of BrC and secondary BrC from July 1st to 31st, 2022 (summer) and January 20th to February 20th, 2023 (winter) in Chongqing. BrC and secondary BrC light absorption were estimated via a seven- wavelength aethalometer and the statistical approach. The average values of secondary BrC light absorption (Abs(BrC,sec,lambda)) accounted for 46.2-56.5% of Abs(BrC). Abs(BrC,370) and Abs(BrC,sec,370) were significantly higher during winter (26.2 +/- 13.2 and 9.1 +/- 5.2 Mm(-1) respectively) than that during summer (7.2 +/- 4.1 and 5.2 +/- 3.5 Mm(-1) respectively) (p < 0.001), suggesting secondary formation played an essential role in BrC. A diurnal cycle of Abs(BrC,sec,370) was explained by the photobleaching of light-absorbing chromophores under the oxidizing conditions in the daytime, and the formation of chromophores via aqueous reactions with NH(4)(+ )and NO(x )after sunset during winter. PSCF analysis showed that transport of anthropogenic emissions from the northeastern and southeastern areas of Chongqing was the important source of the secondary BrC in PP during winter. During winter, the average values of SFEBrC and SFEBrC,sec were 31.9 and 27.4 W g(-1) lower than that during summer (64.7 and 44.5 W g(-1)), respectively. In contrast, J[NO2] values of SFEBrC and SFEBrC,sec decreased by 23.3% and 8.7% during winter higher than that during summer (19.9% and 5.6%), indicating that BrC and secondary BrC cause substantial radiative effects and atmospheric photochemistry. Overall, this study is helpful in understanding the characterization and secondary formation of BrC and accurately evaluating the environmental effects of BrC in Chongqing.

Char-EC and soot-EC in the atmosphere produced from different fuel combustion have distinct optical properties which lead to different radiative forcing. Pollutants transported into high-altitude environment could have a long-lasting radiative effect due to being free of deposition. In this study, the mass absorption cross- (MAC), the sources, transport pathways and the direct radiative effects (DREs) of soot-EC and char-EC were investigated at a peak of Mountain Hua (Mt. Hua) in China. The measurement results showed that soot-EC and char-EC account for 15.7 % and 84.3 % of EC, respectively. The mean MAC (lambda = 633 nm) of soot-EC (13.7 +/- 3.8 m(2)/g) was much higher than that of char-EC (5.4 +/- 2.5 m(2)/g), indicating a stronger light absorption ability for soot-EC. During the study period, 62.1 % char-EC was from anthracite chunk coal, 24.3 % of it from liquid fuel combustion. By contrast, 59.0 % soot-EC from liquid fuel combustion and 36.6 % of it from anthracite chunk coal. EC (both char-EC and soot-EC) produced from anthracite chunk coal reached the peak of the Mt. Hua primarily through the raising of the planetary boundary layer (PBL), while the EC produced from liquid fuel arrived the peak mainly by the regional transport above the PBL of the site. Although soot-EC has a stronger ability (2.8 times higher) to absorb the light compared with char-EC, its DRE (5.7 +/- 3.9 W m(-2)) was lower than that of char-EC (11.6 +/- 6.9 W m(-2)) due to the smaller mass quantity. Liquid fuel consumption contributed 3.5 +/- 2.9 W m(-2) DRE of soot-EC, while the combustion of anthracite chunk coal contributed 7.5 +/- 5.7 W m(-2) DRE of char-EC. This study highlights the differences in DREs of soot-EC and char-EC from fossil fuel combustion and the DRE mass efficiency of soot-EC and char-EC. The results emphasize the divergent climate warming effects caused by the combustion of different fossil fuels and imply that setting path to a green transition of energy use would benefit reducing the EC perturbation to the radiation balance of earth-atmosphere.

Groundwater (GW) is sensitive to climate change (CC), and the effects have become progressively more evident in recent years. Many studies have examined the effects of CC on GW quantity. Still, there is growing interest in assessing the qualitative impacts of CC, especially on GW temperature (GWT), and the consequences of these impacts. This study aimed to systematically review recently published papers on CC and GWT, determine the impacts of CC on GWT, and highlight the possible consequences. The Scopus and Web of Science databases were consulted, from which 144 papers were obtained. After an initial screening for duplicate papers, a second screening based on the titles and abstracts, and following an analysis of topic applicability to this subject after examining the full text, 44 studies were included in this review. The analysed scientific literature, published in 29 different journals, covered all five continents from 1995 to 2023. This review indicated that the subject of GWT variations due to CC is of global interest and has attracted significant attention, especially over the past two decades, with many studies adopting a multidisciplinary approach. A general increase in GWT was noted as a primary effect of CC (especially in urban areas); furthermore, the implications of this temperature increase for contaminants and GW-dependent ecosystems were analysed, and various applications for this increase (e.g. geothermal) were evaluated. This review highlights that GWT is vulnerable to CC and that the consequences can be serious and worthy of further investigation.

Tibetan Plateau (TP) is known as the water tower of Asia, and glaciers are solid reservoirs that can regulate the amount of water. Black carbon (BC), as one of the important factors accelerating glacier melting, is causing evident environmental effects in snow and ice. However, a systematical summary of the potential sources, analytical methods, distributions, and environmental effects of BC in snow and ice on the TP's glaciers is scarce. Therefore, this study drew upon existing research on snow and ice BC on glaciers of the TP to describe the detection methods and uncertainties associated with them to clarify the concentrations of BC in snow and ice and their climatic effects. The primary detection methods are the optical method, the thermal-optical method, the thermochemical method, and the single-particle soot photometer method. However, few studies have systematically compared the results of BC and this study found that concentrations of BC in different types of snow and ice varied by 1-3 orders of magnitude, which drastically affected the regional hydrologic process by potentially accelerating the ablation of glaciers by approximately 15% and reducing the duration of snow accumulation by 3-4 days. In general, results obtained from the various testing methods differ drastically, which limited the systematical discussion. Accordingly, a universal standard for the sampling and measurement should be considered in the future work, which will be beneficial to facilitate the comparison of the spatiotemporal features and to provide scientific data for the model-simulated climatic effects of BC.

The Tibetan Plateau, referred as the last pure land on the earth, is frequently exposure to heavy air pollution during springtime. Here, we find South Asia biomass burning is crucial to cause the heavy springtime air pollution over the Tibetan Plateau, which explain the most (more than 60%) of aerosol components in the region, although its contribution to gaseous pollutants is not significant. South Asian biomass burning mainly affects primary PM2.5 components black carbon (65.3%) and organic carbon (79.5%) over the Tibetan Plateau, but has little influence (less than 5%) on second aerosol components (sulfate, nitrate, and ammonium). The transboundary transmissions of aerosols were regulated by a combination of large-scale westerly winds and regional mountain-valley winds in springtime. In addition to worsen air quality, aerosols from South Asian biomass burning lead to surface temperature decrease of 0.06 degrees C, and precipitation reduction of 3.9 mm over the Tibetan Plateau during springtime. These climate changes will threat the fragile ecosystem over the Tibetan Plateau, such as plant growth and flowering during springtime. Overall, our findings demonstrate a necessary and urgency to reduce biomass burning emissions over South Asia to protect the Tibetan Plateau environment.

The impact of aerosols, especially the absorbing aerosols, in the Himalayan region is important for climate. We closely examine ground-based high-quality observations of aerosol characteristics including radiative forcing from several locations in the Indo-Gangetic Plain (IGP), the Himalayan foothills and the Tibetan Plateau, relatively poorly studied regions with several sensitive ecosystems of global importance, as well as highly vulnerable large populations. This paper presents a state-of-the-art treatment of the warming that arises from these particles, using a combination of new measurements and modeling techniques. This is a first-time analysis of its kind, including ground-based observations, satellite data, and model simulations, which reveals that the aerosol radiative forcing efficiency (ARFE) in the atmosphere is clearly high over the IGP and the Himalayan foothills (80-135 Wm(-2) per unit aerosol optical depth (AOD)), with values being greater at higher elevations. AOD is >0.30 and single scattering albedo (SSA) is similar to 0.90 throughout the year over this region. The mean ARFE is 2-4 times higher here than over other polluted sites in South and East Asia, owing to higher AOD and aerosol absorption (i.e., lower SSA). Further, the observed annual mean aerosol induced atmospheric heating rates (0.5-0.8 Kelvin/day), which are significantly higher than previously reported values for the region, imply that the aerosols alone could account for >50 % of the total warming (aerosols + greenhouse gases) of the lower atmosphere and surface over this region. We demonstrate that the current state-of-the-art models used in climate assessments significantly underestimate aerosol-induced heating, efficiency and warming over the Hindu Kush - Himalaya - Tibetan Plateau (HKHTP) region, indicating a need for a more realistic representation of aerosol properties, especially of black carbon and other aerosols. The significant, regionally coherent aerosol induced warming that we observe in the high altitudes of the region, is a significant factor contributing to increasingair temperature, observed accelerated retreat of the glaciers, and changes in the hydrological cycle and precipitation patterns over this region. Thus, aerosols are heating up the Himalayan climate, and will remain a key factor driving climate change over the region.

Seasonal snow cover has an important impact on the difference between soil- and air temperature because of the insulation effect, and is therefore a key parameter in ecosystem models. However, it is still uncertain how specific variations in soil moisture, vegetation composition, and surface air warming, combined with snow dynamics such as compaction affect the difference between soil- and air temperature. Here, we present an analysis of 8 years (2012-2020) of snow dynamics in an Arctic ecosystem manipulation experiment (using snow fences) on Disko Island, West Greenland. We explore the snow insulation effect under different treatments (mesic tundra heath as a dry site and fen area as a wet site, snow addition from snow fences, warming using open top chambers, and shrub removal) on a plot-level scale. The snow fences significantly changed the inter-annual variation in snow depths and -phenology. The maximum annual mean snow depths were 90 cm on the control side and 122 cm on the snow addition side during all study years. Annual mean snow cover duration across 8 years was 234 days on the control side and 239 days on the snow addition side. The difference between soil- and air temperature was significantly higher on the snow addition side than on the control side of the snow fences. Based on a linear mixed-effects model, we conclude that the snow depth was the decisive factor affecting the difference between soil- and air temperature in the snow cover season (p < 0.0001). The change rate of the difference between soil- and air temperature, as a function of snow depth, was slower during the period before maximum snow depth than during the period between the day with maximum snow depth until snow ending day. During the snow-free season, the effects of the open top chambers were stronger than the effects of the shrub removal, and the combination of both contributed to the highest soil temperature in the dry site, but the warming effect of open top chambers was limited and shrub removal warmed soil temperature in the wet site. The warming effects of open top chambers and shrub removal were weakened on the snow addition side, which indicates a lagged effect of snow on soil temperature. This study quantifies important dynamics in soil-air temperature offsets linked to both snow and ecosystem changes mimicking climate change and provides a reference for future surface process simulations.

Environmental Impact Assessment (EIA) became mandatory in Pakistan in 1983 with the passage of the Pakistan Environmental Protection Ordinance. The Sustainable Development Goals were incorporated into Pakistan's national development strategy, making it the first country in history to do so. The study is based on evaluating the mitigation strategies and environmental impact assessment at the Gulpur Hydropower Project (HPP), Kotli, AJK, which uses the Poonch River's water resources to generate power and has a design capacity of 100 MW using the EIA documentation of Gulpur HPP. In addition to making additional observations and reviewing the literature, the study looked at Mira Power Limited's EIA reports. The possible effects, as well as the Government's and MPL's mitigating actions, were examined by the authors. EIA procedures at the Gulpur HPP considered several laws, including the Pakistan Environmental Protection Agency, AJK Wildlife Ordinance of 2013, the Land Acquisition Act of 1894, and Laws Regulating Flow Releases for Hydropower Projects. Projects using hydropower in delicate areas carry a high risk. Given the thorough analysis of the hazards in this instance, it is evident that the EIA had a significant impact on the project's design. The authors concluded that there are no negative environmental effects of the construction of hydropower projects in the concerned area and that all potential effects and compensation were handled legally and efficiently. The study suggested that all hydropower projects in Pakistan undertake environmental impact assessments. Evaluating the mitigation strategies and environmental impact assessment at the Gulpur Hydropower Project.EIA procedures at the Gulpur HPP considered several laws, including the Pakistan Environmental Protection Agency.The development of hydropower projects in the affected area had no negative environmental effects, and any potential effects or compensation were handled lawfully and effectively.

Arctic river discharge is one of the important factors affecting sea-ice melting of Arctic shelf seas. However, such effects have not been given much attention. In this study, the changes in discharge of the Ob, Yenisei, and Lena Rivers and the sea ice of the Kara and Laptev Seas during 1979-2019 were analyzed. Substantial increases in discharge and heat from the discharge and decreases in sea ice concentration (SIC) were detected. The effects of changes in discharge and riverine heat on sea ice changes were investigated. The results showed that the influence of the discharge, accumulated discharge, heat, and accumulated heat on SIC mainly occurred at the beginning and final stages of sea-ice melting. Discharge accelerated the melting of sea ice by increasing the absorption of solar radiation as the impurities contained in the discharge washed to the sea ice surface during the initial and late stages of sea-ice melting. Changes in cumulative riverine heat from May to September greatly contributed to the SIC changes in the Kara and Laptev Seas at the seasonal scale. The SIC reduced by 1% when the cumulative riverine heat increased by 213.2 x 10(6) MJ, 181.5 x 10(6) MJ, and 154.6 x 10(6) MJ in the Lena, Yenisei, and Ob Rivers, respectively, from May to September. However, even in the plume coverage areas in the Kara and Laptev Seas, discharge changes from the three rivers had a limited contribution to the reduction in SIC at annual scales. This work is helpful for understanding the changes in Arctic sea ice.