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Journal articleSaceanu MC, Paluszny A, Ivars DM, et al., 2024,
Thermo-mechanical modelling of spalling around the deposition boreholes in an underground nuclear waste repository during its thermal phase
, International Journal of Rock Mechanics and Mining Sciences, Vol: 183, ISSN: 1365-1609This paper presents a three-dimensional numerical analysis of multiple fracture growth leading to the development of excavation disturbed zones and spalling around deposition boreholes in a geological disposal facility. The development of fracture patterns is simulated with the Imperial College Geomechanics Toolkit, a finite-element based simulator that can model the simultaneous nucleation, growth, and coalescence of multiple fractures in quasi-brittle rock. In these simulations, fractures develop due to the stress concentrations around the borehole wall, caused by the local in situ stresses, and due to the thermal stresses caused by the radioactive decay of the waste. Fracture patterns, and the extent of the spalled zone, are computed after the borehole drilling, heating, and cooling stages, at the Forsmark repository site in Sweden. The effect of temperature on the nucleation and growth of spalling fractures, as well as on the reactivation of pre-existing fractures, is assessed qualitatively, by comparing fracture patterns, and quantitatively, in terms of the maximum spalling depth, width, and increase in the total fractured surface area. Overall, the simulations presented herein indicate that thermal spalling will increase the depths (away from the borehole) and angular widths of the spalled zone, but is not likely to lead to major increases in fracture aperture, and concomitant increases in hydraulic transmissivity and permeability of the spalled zone, above that which has already been caused by mechanical spalling.
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Journal articleHuybrechts I, Chimera B, Hanley-Cook GT, et al., 2024,
Food biodiversity and gastrointestinal cancer risk in nine European countries: analysis within a prospective cohort study
, European Journal of Cancer, Vol: 210, ISSN: 0959-8049BackgroundFood biodiversity in human diets has potential co-benefits for both public health and sustainable food systems. However, current evidence on the potential relationship between food biodiversity and cancer risk, and particularly gastrointestinal cancers typically related to diet, remains limited. This study evaluated how dietary species richness (DSR) was associated with gastrointestinal cancer risk in a pan-European population.MethodsAssociations between DSR and subsequent gastrointestinal cancer risk were examined among 450,111 adults enrolled in the European Prospective Investigation into Cancer and Nutrition cohort (EPIC, initiated in 1992), free of cancer at baseline. Usual dietary intakes were assessed at recruitment with country-specific dietary questionnaires. DSR of an individual’s yearly diet was calculated based on the absolute number of unique biological species in each food and drink item. Associations between DSR and cancer risk were assessed by multivariable Cox proportional hazards regression models.FindingsDuring a median follow-up time of 14.1 years (SD=3.9), 10,705 participants were diagnosed with gastrointestinal cancer. Hazard ratios (HRs) and 95 % confidence intervals (CIs) comparing overall gastrointestinal cancer risk in the highest versus lowest quintiles of DSR indicated inverse associations in multivariable-adjusted models [HR (95 % CI): 0.77 (0.69–0.87); P-value < 0·0001] (Table 2). Specifically, inverse associations were observed between DSR and oesophageal squamous cell carcinoma, proximal colon, colorectal, and liver cancer risk (p-trend<0.05 for all cancer types).InterpretationGreater food biodiversity in the diet may lower the risk of certain gastrointestinal cancers. Further research is needed to replicate these novel findings and to understand potential mechanisms.
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Journal articleLi J, Prentice IC, 2024,
Global patterns of plant functional traits and their relationships to climate
, Communications Biology, ISSN: 2399-3642 -
Journal articleCavan EL, Mackay N, Hill SL, et al., 2024,
Antarctic krill sequester similar amounts of carbon to key coastal blue carbon habitats
, Nature Communications, Vol: 15, ISSN: 2041-1723The carbon sequestration potential of open-ocean pelagic ecosystems is vastly under-reported compared to coastal vegetation ‘blue carbon’ systems. Here we show that just a single pelagic harvested species, Antarctic krill, sequesters a similar amount of carbon through its sinking faecal pellets as marshes, mangroves and seagrass. Due to their massive population biomass, fast-sinking faecal pellets and the modest depths that pellets need to reach to achieve sequestration (mean is 381 m), Antarctic krill faecal pellets sequester 20 MtC per productive season (spring to early Autumn). This is equates USD$ 4 − 46 billion depending on the price of carbon, with krill pellet carbon stored for at least 100 years and with some reaching as far as the North Pacific. Antarctic krill are being impacted by rapid polar climate change and an expanding fishery, thus krill populations and their habitat warrant protection to preserve this valuable carbon sink.
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Journal articleStocker B, Dong N, Perkowski EA, et al., 2024,
Empirical evidence and theoretical understanding ofecosystem carbon and nitrogen cycle interactions
, New Phytologist, ISSN: 0028-646X -
Journal articleJeong S, Ryu Y, Gentine P, et al., 2024,
Persistent global greening over the last four decades using novel long-term vegetation index data with enhanced temporal consistency
, Remote Sensing of Environment, Vol: 311, ISSN: 0034-4257Advanced Very High-Resolution Radiometer (AVHRR) satellite observations have provided the longest global daily records from 1980s, but the remaining temporal inconsistency in vegetation index datasets has hindered reliable assessment of vegetation greenness trends. To tackle this, we generated novel global long-term Normalized Difference Vegetation Index (NDVI) and Near-Infrared Reflectance of vegetation (NIRv) datasets derived from AVHRR and Moderate Resolution Imaging Spectroradiometer (MODIS). We addressed residual temporal inconsistency through three-step post processing including cross-sensor calibration among AVHRR sensors, orbital drifting correction for AVHRR sensors, and machine learning-based harmonization between AVHRR and MODIS. After applying each processing step, we confirmed the enhanced temporal consistency in terms of detrended anomaly, trend and interannual variability of NDVI and NIRv at calibration sites. Our refined NDVI and NIRv datasets showed a persistent global greening trend over the last four decades (NDVI: 0.0008 yr−1; NIRv: 0.0003 yr−1), contrasting with those without the three processing steps that showed rapid greening trends before 2000 (NDVI: 0.0017 yr−1; NIRv: 0.0008 yr−1) and weakened greening trends after 2000 (NDVI: 0.0004 yr−1; NIRv: 0.0001 yr−1). These findings highlight the importance of minimizing temporal inconsistency in long-term vegetation index datasets, which can support more reliable trend analysis in global vegetation response to climate changes.
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Journal articleFlo V, Joshi J, Sabot M, et al., 2024,
Incorporating photosynthetic acclimation improves stomatal optimisation models
, Plant, Cell and Environment, Vol: 47, Pages: 3478-3493, ISSN: 0140-7791Stomatal opening in plant leaves is regulated through a balance of carbon and water exchange under different environmental conditions. Accurate estimation of stomatal regulation is crucial for understanding how plants respond to changing environmental conditions, particularly under climate change. A new generation of optimality-based modelling schemes determines instantaneous stomatal responses from a balance of trade-offs between carbon gains and hydraulic costs, but most such schemes do not account for biochemical acclimation in response to drought. Here, we compare the performance of six instantaneous stomatal optimisation models with and without accounting for photosynthetic acclimation. Using experimental data from 37 plant species, we found that accounting for photosynthetic acclimation improves the prediction of carbon assimilation in a majority of the tested models. Photosynthetic acclimation contributed significantly to the reduction of photosynthesis under drought conditions in all tested models. Drought effects on photosynthesis could not accurately be explained by the hydraulic impairment functions embedded in the stomatal models alone, indicating that photosynthetic acclimation must be considered to improve estimates of carbon assimilation during drought.
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Journal articleLi L, Collier J, Henstock T, et al., 2024,
Downward continued ocean bottom seismometer data show continued hydrothermal evolution of mature oceanic upper crust
, Geology, Vol: 52, Pages: 717-722, ISSN: 0091-7613Heat flow measurements indicate hydrothermal activity in oceanic crust continues at least for 65 m.y. after formation. Hydrothermal activity progressively fills cracks and pores with alteration products, which is expected to lead to a trend of increasing seismic velocities with age. Compilations of seismic-P-wave velocity models inverted from ocean bottom seismometer (OBS) data have failed to detect such an aging trend beyond crustal ages of ca. 10 Ma. However, in these models, the velocities of the uppermost crust, where fluid flow would be most concentrated, are poorly resolved. This is because as the oceanic crust matures, the first crustal arrivals on OBS records (which best resolve upper crustal velocities using tomographic inversion), become hidden in the coda of the water wave. This may lead to the masking of any aging trend in the seismic velocities. For the first time, we show how including downward continuation (DC) in the analysis of OBS data collected across 65 Ma seafloor significantly improves measurements of the P-wave velocities of the upper crust. Our new analysis reveals a highly heterogeneous upper crust, with ridge-parallel P-wave velocity variations of 25%, implying local porosity values that are up to double that of global averages. Our new results, combined with other most recent advanced seismic analyses, reveal that seismic velocities indeed evolve with age up to at least 70 Ma, confirming that hydrothermal activity continues in mature oceanic crust.
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Journal articleBoran I, Pettorelli N, Köberle AC, et al., 2024,
Making Global Climate Action work for nature and people: Priorities for Race to Zero and Race to Resilience
, Environmental Science and Policy, Vol: 159, ISSN: 1462-9011There is increasing recognition in science and policy that the current nature and climate change crises are highly intertwined, and that these need to be jointly addressed. Within the United Nations Framework Convention on Climate Change (UNFCCC), the Race to Zero (R2Z) and the Race to Resilience (R2R) campaigns foster climate action by cities, regions, businesses, investors, and civil society organizations for mitigation and adaptation. The campaigns are part of UNFCCC-backed institutional arrangements linking intergovernmental climate governance with actions beyond national commitments to support the implementation of the Paris Agreement, also referred to as the Global Climate Action Agenda (GCAA). Both mobilization campaigns highlight and promote the contribution of nature to climate mitigation, adaptation, and resilience. Yet, the integration of nature in climate ambition is more complex than indicated in the calls to action. We here identify key areas of concern in the alignment of climate and biodiversity goals, discussing the biophysical and socio-ecological considerations relative to (i) practices for enhancing land-based and marine sinks to limit warming; (ii) the unpredictability of biodiversity dynamics under climate change; (iii) the spatial scale at which actions can be implemented; and (iv) the types of metrics that can be used for tracking progress. We provide recommendations for the two mobilization campaigns to integrate in their criteria and metrics frameworks to support effective and equitable actions that deliver for climate, but also for nature and people. We then make a call to action for transdisciplinary knowledge production and dissemination that strengthens science-policy interactions.
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Journal articleDechant B, Kattge J, Pavlick R, et al., 2024,
Intercomparison of global foliar trait maps reveals fundamental differences and limitations of upscaling approaches
, Remote Sensing of Environment, Vol: 311, ISSN: 0034-4257Foliar traits such as specific leaf area (SLA), leaf nitrogen (N), and phosphorus (P) concentrations play important roles in plant economic strategies and ecosystem functioning. Various global maps of these foliar traits have been generated using statistical upscaling approaches based on in-situ trait observations. Here, we intercompare such global upscaled foliar trait maps at 0.5° spatial resolution (six maps for SLA, five for N, three for P), categorize the upscaling approaches used to generate them, and evaluate the maps with trait estimates from a global database of vegetation plots (sPlotOpen). We disentangled the contributions from different plant functional types (PFTs) to the upscaled maps and quantified the impacts of using different plot-level trait metrics on the evaluation with sPlotOpen: community weighted mean (CWM) and top-of-canopy weighted mean (TWM). We found that the global foliar trait maps of SLA and N differ drastically and fall into two groups that are almost uncorrelated (for P only maps from one group were available). The primary factor explaining the differences between these groups is the use of PFT information combined with remote sensing-derived land cover products in one group while the other group mostly relied on environmental predictors alone. The maps that used PFT and corresponding land cover information exhibit considerable similarities in spatial patterns that are strongly driven by land cover. The maps not using PFTs show a lower level of similarity and tend to be strongly driven by individual environmental variables. Upscaled maps of both groups were moderately correlated to sPlotOpen data aggregated to the grid-cell level (R = 0.2–0.6) when processing sPlotOpen in a way that is consistent with the respective trait upscaling approaches, including the plot-level trait metric (CWM or TWM) and the scaling to the grid cells with or without accounting for fractional land cover. The impact of using TWM or CWM was relevant
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