Large stocks of soil organic carbon (SOC) have accumulated in the Northern Hemisphere permafrost region, but their current amounts and future fate remain uncertain. By analyzing dataset combining >2700 soil profiles with environmental variables in a geospatial framework, we generated spatially explicit estimates of permafrost-region SOC stocks, quantified spatial heterogeneity, and identified key environmental predictors. We estimated that Pg C are stored in the top 3 m of permafrost region soils. The greatest uncertainties occurred in circumpolar toe-slope positions and in flat areas of the Tibetan region. We found that soil wetness index and elevation are the dominant topographic controllers and surface air temperature (circumpolar region) and precipitation (Tibetan region) are significant climatic controllers of SOC stocks. Our results provide first high-resolution geospatial assessment of permafrost region SOC stocks and their relationships with environmental factors, which are crucial for modeling the response of permafrost affected soils to changing climate.

All global circulation models based on Intergovernmental Panel on Climate Change (IPCC) scenarios project profound changes, but there is no consensus on how to map their environmental consequences. Our multivariate representation of environmental space combines stable topographic and edaphic attributes with dynamic climatic attributes. We divide that environmental space into 500 unique domains and map their current locations and their projected locations in 2100 under contrasting emissions scenarios. The environmental domains found across half the study area today disappear under the higher emissions scenario, but persist somewhere in it under the lower emissions scenario. Locations affected least and those affected most under each scenario are mapped. This provides an explicit framework for designing conservation networks to include both areas at least risk (potential refugia) and areas at greatest risk, where novel communities may form and where sentinel ecosystems can be monitored for signs of stress.

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As the effects of anthropogenic climate change become more severe, several approaches for deliberate climate intervention to reduce or stabilize Earth’s surface temperature have been proposed. Solar radiation modification (SRM) is one potential approach to partially counteract anthropogenic warming by reflecting a small proportion of the incoming solar radiation to increase Earth’s albedo. While climate science research has focused on the predicted climate effects of SRM, almost no studies have investigated the impacts that SRM would have on ecological systems. The impacts and risks posed by SRM would vary by implementation scenario, anthropogenic climate effects, geographic region, and by ecosystem, community, population, and organism. Complex interactions among Earth’s climate system and living systems would further affect SRM impacts and risks. We focus here on stratospheric aerosol intervention (SAI), a well-studied and relatively feasible SRM scheme that is likely to have a large impact on Earth’s surface temperature. We outline current gaps in knowledge about both helpful and harmful predicted effects of SAI on ecological systems. Desired ecological outcomes might also inform development of future SAI implementation scenarios. In addition to filling these knowledge gaps, increased collaboration between ecologists and climate scientists would identify a common set of SAI research goals and improve the communication about potential SAI impacts and risks with the public. Without this collaboration, forecasts of SAI impacts will overlook potential effects on biodiversity and ecosystem services for humanity.

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The present investigation aims to optimize the process parameters of Direct Current (DC) and Radio Frequency (RF) glow discharge treatment through air in terms of discharge power and time of exposure for the surface modification of high-density polyethylene (HDPE) sheet, for attaining best adhesive joint of the polymer to mild steel. In order to estimate the extent of surface modification, the surface energies of the polymer surfaces exposed to glow discharge have been determined by measuring contact angles using two standard test liquids of known surface energies. It is observed that at a given power level of DC glow discharge, surface energy and its polar component increase with increasing exposure time, attaining a maximum and then decreasing. In the case of RF glow discharge, surface energy and its polar component increase with increasing exposure time and then saturate. Surface modification by DC glow discharge increases the surface energy of HDPE relatively more at a lower power compared to that observed for RF glow discharge. The dispersion component of surface energy remains almost unaffected. The surfaces have also been studied by electron spectroscopy for chemical analysis (ESCA) and energy-dispersive spectra (EDS). A significant oxygen peak is observed for surface-modified polymer as detected by ESCA and EDS. Lap shear tensile test of an adhesive (Araldite AY 105) joint of HDPE with mild steel has been carried out in optimizing the parameters of DC and RF glow discharge for maximum joint strength. When HDPE is exposed to DC glow discharge, improvement of adhesive joint strength of HDPE to mild steel is found to be by a factor more than 7. On the other hand, when HDPE is exposed to RF glow discharge, results in improvement of adhesive joint strength of HDPE to mild steel by a factor nearer to 7 are found. Thus, DC glow discharge is more capable for increasing wetting and adhesion characteristics of the polymer.

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