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Climate change is rapidly altering hydrological processes and consequently the structure and functioning of Arctic ecosystems. Predicting how these alterations will shape biogeochemical responses in rivers remains a major challenge. We measured [C]arbon and [N]itrogen concentrations continuously from two Arctic watersheds capturing a wide range of flow conditions to assess understudied event‐scale C and N concentration‐discharge (C‐Q) behavior and post‐event recovery of stoichiometric conditions. The watersheds represent low‐gradient, tundra landscapes typical of the eastern Brooks Range on the North Slope of Alaska and are part of the Arctic Long‐Term Ecological Research sites: the Kuparuk River and Oksrukuyik Creek. In both watersheds, we deployed high‐frequency optical sensors to measure dissolved organic carbon (DOC), nitrate (), and total dissolved nitrogen (TDN) for five consecutive thaw seasons (2017–2021). Our analyses revealed a lag in DOC: stoichiometric recovery after a hydrologic perturbation: while DOC was consistently elevated after high flows, diluted during rainfall events and consequently, recovery in post‐event concentration was delayed. Conversely, the co‐enrichment of TDN at high flows, even in watersheds with relatively high N‐demand, represents a potential “leak” of hydrologically available organic N to downstream ecosystems. Our use of high‐frequency, long‐term optical sensors provides an improved method to estimate carbon and nutrient budgets and stoichiometric recovery behavior across event and seasonal timescales, enabling new insights and conceptualizations of a changing Arctic, such as assessing ecosystem disturbance and recovery across multiple timescales.

 

Understanding methane (CH₄) emission from thermokarst lakes is crucial for predicting the impacts of abrupt thaw on the permafrost carbon-climate feedback. However, observational evidence, especially from high-altitude permafrost regions, is still scarce. Here, by combining field surveys, radio- and stable-carbon isotopic analyses, and metagenomic sequencing, we present multiple characteristics of CH₄emissions from 120 thermokarst lakes in 30 clusters along a 1100 km transect on the Tibetan Plateau. We find that thermokarst lakes have high CH₄emissions during the ice-free period (13.4 ± 1.5 mmol m⁻²d⁻¹; mean ± standard error) across this alpine permafrost region. Ebullition constitutes 84% of CH₄emissions, which are fueled primarily by young carbon decomposition through the hydrogenotrophic pathway. The relative abundances of methanogenic genes correspond to the observed CH₄fluxes. Overall, multiple parameters obtained in this study provide benchmarks for better predicting the strength of permafrost carbon-climate feedback in high-altitude permafrost regions.

 

The Intergovernmental Panel on Climate Change concludes that climate change has already caused substantial damages at the current 1.2°C of global warming and that warming of 1.5°C would elevate risks of a wide-range of climate tipping points. For example, wet-bulb temperatures are already exceeding safe levels, and the melting of the Greenland and West Antartic ice sheets would lead to over ten metres of sea level rise, representing an existential threat to coastal cities, low-lying nation states, and human wellbeing worldwide. We call for a broad scientific discussion about a stricter and more ambitious climate target of 1.0°C by the end of this century. Comprehensive electrification and highly renewable energy systems offer a pathway to sub-1.5°C futures through rapid defossilisation and large-scale, electricity-based carbon dioxide removal. Independent scenarios show that restoring a stable and safe climate is attainable with coordinated policy and economic support.

 

Key Points We compared tools for describing streamflow timeseries, including streamflow metrics, wavelet, and Fourier analysis Each method indicated streamflow data are structured: variability at short timescales is negatively correlated with long timescales Globally, dams were less correlated with streamflow regime than catchment size and climate were 

Abstract Estimates of the permafrost-climate feedback vary in magnitude and sign, partly because permafrost carbon stability in warmer-than-present conditions is not well constrained. Here we use a Plio-Pleistocene lacustrine reconstruction of mean annual air temperature (MAAT) from the Tibetan Plateau, the largest alpine permafrost region on the Earth, to constrain past and future changes in permafrost carbon storage. Clumped isotope-temperatures (Δ 47 -T) indicate warmer MAAT (~1.2 °C) prior to 2.7 Ma, and support a permafrost-free environment on the northern Tibetan Plateau in a warmer-than-present climate. Δ 47 -T indicate ~8.1 °C cooling from 2.7 Ma, coincident with Northern Hemisphere glacial intensification. Combined with climate models and global permafrost distribution, these results indicate, under conditions similar to mid-Pliocene Warm period (3.3–3.0 Ma), ~60% of alpine permafrost containing ~85 petagrams of carbon may be vulnerable to thawing compared to ~20% of circumarctic permafrost. This estimate highlights ~25% of permafrost carbon and the permafrost-climate feedback could originate in alpine areas. 

Unsustainable agriculture practices are undermining the world's future ability to reliably produce food. Assistance programmes, such as those offered by the Natural Resource Conservation Service (NRCS) of the United States, can increase the uptake of sustainable practices, yet implementation of these alternatives in the US remains discouragingly limited. In this context, we used an interdisciplinary approach involving quantitative and qualitative data to assess the current efficacy of NRCS assistance programmes and identify areas for improvement. To do so, we first analyzed national reports of NRCS expenditures and acres treated over the last 15 years and then distributed an explorative survey to farmers and ranchers throughout Utah state. Our NRCS programme analysis suggested that historical increases in expenditures have been ineffective at increasing the number of acres treated. The survey responses indicated that both financial and non-financial factors were influential in farmer decisions. Farmers that assigned a high importance to sustainable practices were motivated by public perception and environmental stewardship while those that assigned a moderate importance were motivated by the potential return on investment. Overall, participants in NRCS programs reported more positive outcomes than expected by non-participants. We hope the findings from this study can guide future research and inform efforts to improve NRCS assistance programmes in Utah and other regions in the US and elsewhere. 

Abstract Nitrogen regulates multiple aspects of the permafrost climate feedback, including plant growth, organic matter decomposition, and the production of the potent greenhouse gas nitrous oxide. Despite its importance, current estimates of permafrost nitrogen are highly uncertain. Here, we compiled a dataset of >2000 samples to quantify nitrogen stocks in the Yedoma domain, a region with organic-rich permafrost that contains ~25% of all permafrost carbon. We estimate that the Yedoma domain contains 41.2 gigatons of nitrogen down to ~20 metre for the deepest unit, which increases the previous estimate for the entire permafrost zone by ~46%. Approximately 90% of this nitrogen (37 gigatons) is stored in permafrost and therefore currently immobile and frozen. Here, we show that of this amount, ¾ is stored >3 metre depth, but if partially mobilised by thaw, this large nitrogen pool could have continental-scale consequences for soil and aquatic biogeochemistry and global-scale consequences for the permafrost feedback.