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OtherWilson Kemsley S, Nowack P, Ceppi P, 2024,
A systematic evaluation of high-cloud controlling factors
<jats:p>Clouds strongly modulate the top-of-the-atmosphere (TOA) energy budget. While most evidence indicates that changes in cloud-induced radiative anomalies at the TOA likely amplifies warming, the magnitude of this global cloud feedback remains highly uncertain. &#8220;Cloud Controlling Factor&#8221; (CCF) analysis is an approach that can be used to tackle this uncertainty, deriving relationships between large-scale meteorological drivers and cloud-radiative anomalies which can subsequently be used to constrain cloud feedback. However, the choice of meteorological controlling factors is crucial for a meaningful constraint, and while there is rich literature investigating ideal CCF setups for low-level clouds, there is a distinct lack of analogous research that explicitly targets high clouds.Here, we use ridge regression to systematically evaluate CCFs that specifically target high cloud formation and cessation using historical data. We evaluate the addition of five candidate CCFs to previously established core CCFs within large spatial domains to predict longwave high-cloud radiative anomalies: upper-tropospheric static stability (SUT), sub-cloud moist static energy, convective available potential energy, convective inhibition, and upper-tropospheric wind shear. We identify an optimal configuration including SUT, and show that the spatial distribution of the&#160; SUT &#160;ridge regression coefficients are congruent with the physical drivers of known high-cloud feedbacks. We further deduce that inclusion of SUT into observational constraint frameworks may reduce uncertainty associated with changes in anvil cloud amount as a function of climate change. These results highlight upper-tropospheric static stability as an important CCF for high clouds and longwave cloud feedback, which we begin to explore using modelled data under an abrupt quadrupling of CO2&#160;(abrupt-4xCO2).</jats:p>
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OtherKuhlbrodt T, Swaminathan R, Ceppi P, et al., 2024,
A glimpse into the future: The 2023 temperature extremes in the North Atlantic in the context of longer-term climate change
<jats:p>In the year 2023, we have seen extraordinary extrema in high sea-surface temperature (SST) in the North Atlantic which are outside the 4-sigma envelope of the 1982-2011 daily timeseries. Here we take a first look at the large-scale, longer-term drivers of these extrema. Earth&#8217;s net global energy imbalance (in the 12 months up to September 2023) amounts to +1.9 W/m2 as part of a remarkably large upward trend, ensuring continuous heating of the ocean. However, the regional radiation budget over the North Atlantic does not show signs of a significant step increase from less negative aerosol forcing since 2020 as was suggested elsewhere. While the temperature in the top 100 m of the global ocean has been rising in all basins since about 1980, specifically the Atlantic basin has continued to further heat up since 2016. Similarly, salinity in the top 100 m of the ocean has increased in recent years specifically in the Atlantic basin. Outside the North Atlantic, around 2015 a substantial negative trend for sea-ice extent in the Southern Ocean has begun, leading to record low sea-ice extent in 2023. We suggest analysing the 2023 temperature extremes in the North Atlantic in the context of these recent global-scale ocean changes. Analysing climate and Earth System model simulations of the future, we find that the extreme SST in the North Atlantic and the extreme in Southern Ocean sea-ice extent in 2023 lie at the fringe of the expected mean climate change for a global surface-air temperature warming level (GWL) of 1.5&#176;C, and closer to the average at a 3.0&#176;C GWL. Understanding the regional and global drivers of these extremes is indispensable for assessing frequency and impacts of similar events in the coming years.</jats:p>
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Journal articleRizos G, Lawson J, Mitchell S, et al., 2024,
Propagating variational model uncertainty for bioacoustic call label smoothing
, Patterns, Vol: 5, ISSN: 2666-3899Along with propagating the input toward making a prediction, Bayesian neural networks also propagate uncertainty. This has the potential to guide the training process by rejecting predictions of low confidence, and recent variational Bayesian methods can do so without Monte Carlo sampling of weights. Here, we apply sample-free methods for wildlife call detection on recordings made via passive acoustic monitoring equipment in the animals' natural habitats. We further propose uncertainty-aware label smoothing, where the smoothing probability is dependent on sample-free predictive uncertainty, in order to downweigh data samples that should contribute less to the loss value. We introduce a bioacoustic dataset recorded in Malaysian Borneo, containing overlapping calls from 30 species. On that dataset, our proposed method achieves an absolute percentage improvement of around 1.5 points on area under the receiver operating characteristic (AU-ROC), 13 points in F1, and 19.5 points in expected calibration error (ECE) compared to the point-estimate network baseline averaged across all target classes.
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Journal articleDo Prado AH, Mair D, Garefalakis P, et al., 2024,
Check dam impact on sediment loads: example of the Guerbe River in the Swiss Alps - a catchment scale experiment
, Hydrology and Earth System Sciences, Vol: 28, Pages: 1173-1190, ISSN: 1027-5606The construction of check dams is a common practice around the world where the aim is to reduce the damage by flooding events through mountain streams. However, quantifying the effectiveness of such engineering structures has remained very challenging and requires well-selected case studies, since the outcome of such an evaluation depends on site-specific geometric, geologic and climatic conditions. Conventionally, the check dams' effectiveness has been estimated using information about how the bedload sediment flux in the stream changes after the check dams are constructed. A permanent lowering of the bedload flux not only points to a success in reducing the probability of sediment transport occurrence but also implies that the sediment input through the system is likely to decrease. Here, we applied a method for data acquisition and two different equations (Meyer-Peter-Müller and Recking approach) to estimate and compare the sediment transport in a mountain stream in Switzerland under engineered and non-engineered conditions. Whereas the first equation is derived from a classical approach that is based on flume experiment data with a slope of less than 0.02mm-1, the second equation (Recking) has been derived based on a bedload field dataset comprising active mountain streams under steeper conditions. We selected the Guerbe (Gürbe) River situated in the Swiss Alps as a case study, which has been engineered since the end of the 19th century. This has resulted in more than 110 check dams along a ca. 5ĝ€¯km reach where sediment has continuously been supplied from adjacent hillslopes, primarily by landsliding. We measured the riverbed grain size, topographic gradients and river widths within selected segments along this reach. Additionally, a gauging station downstream of the reach engineered with check dams yielded information to calibrate the hydroclimatic situation for the study reach, thus offering ideal conditions for our catchment-scale experi
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Journal articleWang W, Gulliver J, Beevers S, et al., 2024,
Short-term nitrogen dioxide exposure and emergency hospital admissions for asthma in children: a case-crossover analysis in England
, Journal of Asthma and Allergy, ISSN: 1178-6965 -
Journal articleRasheed S, Warder SC, Plancherel Y, et al., 2024,
Nearshore tsunami amplitudes across the Maldives archipelago due to worst-case seismic scenarios in the Indian Ocean
, Natural Hazards and Earth System Sciences, Vol: 24, Pages: 737-755, ISSN: 1561-8633The Maldives face the threat of tsunamis from a multitude of sources. However, the limited availability of critical data, such as bathymetry (a recurrent problem for many island nations), has meant that the impact of these threats has not been studied at an island scale. Conducting studies of tsunami propagation at the island scale but across multiple atolls is also a challenging task due to the large domain and high resolution required for modelling. Here we use a high-resolution bathymetry dataset of the Maldives archipelago, as well as corresponding high numerical model resolution, to carry out a scenario-based tsunami hazard assessment for the entire Maldives archipelago to investigate the potential impact of plausible far-field tsunamis across the Indian Ocean at the nearshore island scales across the atolls. The results indicate that the bathymetry of the atolls, which are characterized by very steep boundaries offshore, is extremely efficient in absorbing and redirecting incoming tsunami waves. Results also highlight the importance that local effects have in modulating tsunami amplitude nearshore, including the location of the atoll in question, the location of a given island within the atoll, and the distance of that island to the reef, as well as a variety of other factors. We also find that the refraction and diffraction of tsunami waves within individual atolls contribute to the maximum tsunami amplitude patterns observed across the islands in the atolls. The findings from this study contribute to a better understanding of tsunamis across complex atoll systems and will help decision and policy makers in the Maldives assess the potential impact of tsunamis across individual islands. An online tool is provided which presents users with a simple interface, allowing the wider community to browse the simulation results presented here and assess the potential impact of tsunamis at the local scale.
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ReportJennings N, Paterson P, Whitmarsh L, et al., 2024,
What do the UK public think about the co-benefits that climate action can bring?
This slide deck summarises findings from a nationally representative sample (on the basis of age, gender and ethnicity) of 1,021 people who were asked to share their opinions about the co-benefits of climate action. People were surveyed via the online survey platform Prolific on Monday 12th February 2024. The headline findings and recommendations are followed by a case study focused on homes that are more affordable to heat. The insights in this slide deck build on findings from a Grantham report published in October 2023, How do UK citizens perceive the co-benefits of climate action? which included survey and focus groups with members of the UK public.
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Journal articleMartin Frias A, Shapiro ML, Engberg Z, et al., 2024,
Feasibility of contrail avoidance in a commercial flight planning system: an operational analysis
, Environmental Research: Infrastructure and Sustainability, Vol: 4Aircraft condensation trails, also known as contrails, contribute a substantial portion of aviation’s overall climate footprint. Contrail impacts can be reduced through smart flight planning that avoids contrail-forming regions of the atmosphere. While previous studies have explored the operational impacts of contrail avoidance in simulated environments, this paper aims to characterize the feasibility and cost of contrail avoidance precisely within a commercial flight planning system. This study leverages the commercial Flightkeys 5D algorithm, developed by Flightkeys GmbH, with a prototypical contrail forecast model based on the Contrail Cirrus Prediction (CoCiP) model to simulate contrail avoidance on 49 411 flights during the first two weeks of June 2023, and 35 429 flights during the first two weeks of January 2024. The utilization of a commercial flight planning system enables high-accuracy estimates of additional cost and fuel investments by operators to achieve estimated reductions in contrail-energy forcing and overall flight global warming potential. The results show that navigational contrail avoidance will require minimal additional cost (0.08%) and fuel (0.11%) investments to achieve notable reductions in contrail climate forcing (−73.0%). This simulation provides evidence that contrail mitigation entails very low operational risks, even regarding fuel. This study aims to serve as an incentive for operators and air traffic controllers to initiate contrail mitigation testing as soon as possible and begin reducing aviation’s non- CO 2 emissions.
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Journal articleLiu X, Lara R, Dufresne M, et al., 2024,
Variability of ambient air ammonia in urban Europe (Finland, France, Italy, Spain, and the UK).
, Environ Int, Vol: 185This study addressed the scarcity of NH3 measurements in urban Europe and the diverse monitoring protocols, hindering direct data comparison. Sixty-nine datasets from Finland, France, Italy, Spain, and the UK across various site types, including industrial (IND, 8), traffic (TR, 12), urban (UB, 22), suburban (SUB, 12), and regional background (RB, 15), are analyzed to this study. Among these, 26 sites provided 5, or more, years of data for time series analysis. Despite varied protocols, necessitating future harmonization, the average NH3 concentration across sites reached 8.0 ± 8.9 μg/m3. Excluding farming/agricultural hotspots (FAHs), IND and TR sites had the highest concentrations (4.7 ± 3.2 and 4.5 ± 1.0 μg/m3), followed by UB, SUB, and RB sites (3.3 ± 1.5, 2.7 ± 1.3, and 1.0 ± 0.3 μg/m3, respectively) indicating that industrial, traffic, and other urban sources were primary contributors to NH3 outside FAH regions. When referring exclusively to the FAHs, concentrations ranged from 10.0 ± 2.3 to 15.6 ± 17.2 μg/m3, with the highest concentrations being reached in RB sites close to the farming and agricultural sources, and that, on average for FAHs there is a decreasing NH3 concentration gradient towards the city. Time trends showed that over half of the sites (18/26) observed statistically significant trends. Approximately 50 % of UB and TR sites showed a decreasing trend, while 30 % an increasing one. Meta-analysis revealed a small insignificant decreasing trend for non-FAH RB sites. In FAHs, there was a significant upward trend at a rate of 3.51[0.45,6.57]%/yr. Seasonal patterns of NH3 concentrations varied, with urban areas experiencing fluctuations influenced by surrounding emissions, particularly in FAHs. Diel variation showed differing patterns at urban monitoring sites, all with high
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Journal articleFuertes E, Jarvis D, Lam H, et al., 2024,
Phl p 5 levels more strongly associated than grass pollen counts with allergic respiratory health
, Journal of Allergy and Clinical Immunology, Vol: 153, Pages: 844-851, ISSN: 0091-6749Background:Studies have linked daily pollen counts to respiratory allergic health outcomes but few have considered allergen levels.Objective:This study assessed associations of grass pollen counts and allergen levels (Phl p 5) with 1) respiratory allergic health symptoms in a panel of 93 adults with moderate-severe allergic rhinitis and 2) daily asthma hospital admissions in London, UK.Methods:Daily symptom and medication scores were collected from adult participants in an allergy clinical trial. Daily counts of asthma hospital admissions in the London general population were obtained from Hospital Episode Statistics data. Daily grass pollen counts were measured using a volumetric air sampler, and novel Phl p 5 levels, using a Chemvol high-volume cascade impactor and ELISA analyses (May-August). Associations between the two pollen variables and daily health scores (dichotomized based on within-person 75th percentiles) were assessed using generalized estimating equation logistic models, and with asthma hospital admissions using Poisson regression models.Results:Daily pollen counts and Phl p 5 levels were each positively associated with reporting a high combined symptom and medication health score in separate models. However, in mutually adjusted models including terms for both pollen counts and Phl p 5 levels, associations remained for Phl p 5 levels (odds ratio [95% confidence intervals]: 1.18 [1.12, 1.24]) but were heavily attenuated for pollen counts (1.00 [0.93, 1.07]). Similar trends were not observed for asthma hospital admissions in London.Conclusion:Grass allergen (Phl p 5) levels are more consistently associated with allergic respiratory symptoms than grass pollen counts.
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