Impacts of permafrost thaw on streamflow recession in a discontinuous permafrost watershed of northeastern China

Permafrost thaw due to climate change is altering terrestrial hydrological processes by increasing ground hydraulic conductivity and surface and subsurface hydrologic connectivity across the pan-Arctic. Understanding how runoff responds to changes in hydrologic processes and conditions induced by permafrost thaw is critical for water resources management in high-latitude and high-altitude regions. In this study, we analyzed streamflow recession characteristics for 1964-2016 for the Tahe watershed located at the southern margin of the permafrost region in Eurasia. Results reveal a link between streamflow recession and permafrost degradation as indicated by the statistical analyses of streamflow and the modeled ground warming and active layer thickening. The recession constant and the active layer temperatures at depths of 5, 40, 100, and 200 cm simulated by the backpropagation neural network model significantly increased during the study period from 1972 to 2020 due to intensified climate warming in northeastern China. The onset of seasonal active layer thaw was advanced by 10 days, and the modeled active layer thickness increased by 54 cm in this period. The average annual streamflow recession time increased by 11.5 days (+53 %) from the warming period (1972-1988) to the thawing period (1989-2016), with these periods determined from breakpoint analysis. These hydrologic changes arose from increased catchment storage and were correlated to increased active layer thickness and longer seasonal thawing periods. These results highlight that permafrost degradation can significantly extend the recession flow duration in a watershed underlain by discontinuous, sporadic, and isolated permafrost, and thereby alter flooding dynamics and water resources in the southern margin of the Eurasian permafrost region.

Living conditions and mental wellness in a changing climate and environment: focus on community voices and perceived environmental and adaptation factors in Greenland

BACKGROUND

Climate change is a major global challenge, especially for Indigenous communities. It can have extensive impacts on peoples' lives that may occur through the living environment, health and mental well-being, and which are requiring constant adaptation.

OBJECTIVES

The overall purpose of this research was to evaluate the impacts of climate change and permafrost thaw on mental wellness in Disko Bay, Greenland. It contained two parts: multidisciplinary fieldwork and a questionnaire survey. The aim of the fieldwork was to learn about life and living conditions and to understand what it is like to live in a community that faces impacts of climate change and permafrost thaw. For the questionnaire the aim was to find out which perceived environmental and adaptation factors relate to very good self-rated well-being, quality of life and satisfaction with life.

ANALYSIS

Fieldwork data was analyzed by following a thematic analysis, and questionnaire data statistically by cross-tabulation. First, the associations between perceived environmental and adaptation factors were studied either by the Pearson χ2 test or by Fisher's exact test. Second, binary logistic regression analysis was applied to examine more in depth the associations between perceived environmental/adaptation variables and self-rated very good well-being, satisfaction with life and quality of life. The binary logistic regression analysis was conducted in two phases: as univariate and multivariate analyses.

RESULTS

Nature and different activities in nature were found to be important to local people, and results suggest that they increase mental wellness, specifically well-being and satisfaction with life. Challenges associated with permafrost thaw, such as changes in the physical environment, infrastructure and impacts on culture were recognized in everyday life.

CONCLUSIONS

The results offer relevant information for further plans and actions in this field of research and at the policy level. Our study shows the importance of multidisciplinary research which includes the voice of local communities.

Watershed, climate, and stable isotope data (oxygen-18 and deuterium) for 50 boreal lakes in the oil sands region, northeastern Alberta, Canada, 2002-2017

Watershed data, climate and stable data collected over a 16-year period from a network of 50 lakes in northeastern Alberta, are provided to allow for broader incorporation into regional assessments of environmental impacts, particularly hydrologic and geochemical processes under changing climate and land use development. Oxygen-18 and deuterium analyses of water samples are provided from late summer surveys of 50 lakes with varying land cover and permafrost conditions. Six sub-groups of lakes are represented, including Stony Mountains, West Fort McMurray, Northeast Fort McMurray, Birch Mountains, Caribou Mountains and Shield. This dataset includes 1582 isotopic analyses made on 791 water samples and 3164 isotope mass balance model outputs, as well as 800 lake/watershed parameters, 5600 climate parameters, and 800 modelled values for isotopic composition of precipitation used in the computations. Model data are provided to facilitate evaluation of transferability of the model for other applications, and to permit more sophisticated spatial analysis and intercomparison with geochemical and biological datasets. Details and further discussion on the isotope mass balance approach are provided in “Regional trends in water balance and runoff to fifty boreal lakes: a 16-year isotope mass balance assessment including evaluation of hydrologic drivers” [1]. Overall, the data are expected to be useful, in comparison with local and regional datasets, for water resource management and planning, including design of monitoring networks and environmental impact assessments for oil sands projects.

Shifts of methanogenic communities in response to permafrost thaw results in rising methane emissions and soil property changes

Permafrost thaw can bring negative consequences in terms of ecosystems, resulting in permafrost collapse, waterlogging, thermokarst lake development, and species composition changes. Little is known about how permafrost thaw influences microbial community shifts and their activities. Here, we show that the dominant archaeal community shifts from Methanomicrobiales to Methanosarcinales in response to the permafrost thaw, and the increase in methane emission is found to be associated with the methanogenic archaea, which rapidly bloom with nearly tenfold increase in total number. The mcrA gene clone libraries analyses indicate that Methanocellales/Rice Cluster I was predominant both in the original permafrost and in the thawed permafrost. However, only species belonging to Methanosarcinales showed higher transcriptional activities in the thawed permafrost, indicating a shift of methanogens from hydrogenotrophic to partly acetoclastic methane-generating metabolic processes. In addition, data also show the soil texture and features change as a result of microbial reproduction and activity induced by this permafrost thaw. Those data indicate that microbial ecology under warming permafrost has potential impacts on ecosystem and methane emissions.

Biogeochemistry of "pristine" freshwater stream and lake systems in the western Canadian Arctic

Climate change poses a substantial threat to the stability of the Arctic terrestrial carbon (C) pool as warmer air temperatures thaw permafrost and deepen the seasonally-thawed active layer of soils and sediments. Enhanced water flow through this layer may accelerate the transport of C and major cations and anions to streams and lakes. These act as important conduits and reactors for dissolved C within the terrestrial C cycle. It is important for studies to consider these processes in small headwater catchments, which have been identified as hotspots of rapid mineralisation of C sourced from ancient permafrost thaw. In order to better understand the role of inland waters in terrestrial C cycling we characterised the biogeochemistry of the freshwater systems in a c. 14 km² study area in the western Canadian Arctic. Sampling took place during the snow-free seasons of 2013 and 2014 for major inorganic solutes, dissolved organic and inorganic C (DOC and DIC, respectively), carbon dioxide (CO₂) and methane (CH₄) concentrations from three water type groups: lakes, polygonal pools and streams. These groups displayed differing biogeochemical signatures, indicative of contrasting biogeochemical controls. However, none of the groups showed strong signals of enhanced permafrost thaw during the study seasons. The mean annual air temperature in the region has increased by more than 2.5 °C since 1970, and continued warming will likely affect the aquatic biogeochemistry. This study provides important baseline data for comparison with future studies in a warming Arctic.

Effects of permafrost thaw on carbon emissions under aerobic and anaerobic environments in the Great Hing'an Mountains, China

The carbon (C) pool of permafrost peatland is very important for the global C cycle. Little is known about how permafrost thaw could influence C emissions in the Great Hing'an Mountains of China. Through aerobic and anaerobic incubation experiments, we studied the effects of permafrost thaw on CH4 and CO2 emissions. The rates of CH4 and CO2 emissions were measured at -10, 0 and 10°C. Although there were still C emissions below 0°C, rates of CH4 and CO2 emissions significantly increased with permafrost thaw under aerobic and anaerobic conditions. The C release under aerobic conditions was greater than under anaerobic conditions, suggesting that permafrost thaw and resulting soil environment change should be important influences on C emissions. However, CH4 stored in permafrost soils could affect accurate estimation of CH4 emissions from microbial degradation. Calculated Q10 values in the permafrost soils were significantly higher than values in active-layer soils under aerobic conditions. Our results highlight that permafrost soils have greater potential decomposability than soils of the active layer, and such carbon decomposition would be more responsive to the aerobic environment.