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Journal articleCharnley G, Green N, Malembaka E, et al., 2024,
Evaluating the risk of conflict on recent Ebola outbreaks in Guinea and the Democratic Republic of the Congo
, BMC Public Health, ISSN: 1471-2458 -
Journal articleMarschalek JW, Blard PH, Sarigulyan E, et al., 2024,
Byrd Ice Core Debris Constrains the Sediment Provenance Signature of Central West Antarctica
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276Provenance records from sediments deposited offshore of the West Antarctic Ice Sheet (WAIS) can help identify past major ice retreat, thus constraining ice-sheet models projecting future sea-level rise. Interpretations from such records are, however, hampered by the ice obscuring Antarctica's geology. Here, we explore central West Antarctica's subglacial geology using basal debris from within the Byrd ice core, drilled to the bed in 1968. Sand grain microtextures and a high kaolinite content (∼38–42%) reveal the debris consists predominantly of eroded sedimentary detritus, likely deposited initially in a warm, pre-Oligocene, subaerial environment. Detrital hornblende 40Ar/39Ar ages suggest proximal late Cenozoic subglacial volcanism. The debris has a distinct provenance signature, with: common Permian-Early Jurassic mineral grains; absent early Ross Orogeny grains; a high kaolinite content; and high 143Nd/144Nd and low 87Sr/86Sr ratios. Detecting this “fingerprint” in Antarctic sedimentary records could imply major WAIS retreat, revealing the WAIS's sensitivity to future warming.
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Journal articleReyes AV, Carlson AE, Clark J, et al., 2024,
Timing of Cordilleran-Laurentide ice-sheet separation: Implications for sea-level rise
, Quaternary Science Reviews, Vol: 328, ISSN: 0277-3791During the last deglaciation, collapse of the saddle between the North American Cordilleran and Laurentide ice sheets led to rapid ice-sheet mass loss and separation, with meltwater discharge contributing to deglacial sea-level rise. We directly date ice-sheet separation at the end of the saddle collapse using 64 10Be exposure ages along an ∼1200-km transect of the ice-sheet suture zone. Collapse began in the south by 15.4 ± 0.4 ka and ended by 13.8 ± 0.1 ka at ∼56°N. Ice-sheet model simulations consistent with the 10Be ages find that the saddle collapse contributed 6.2–7.2 m to global mean sea-level rise from ∼15.5 ka to ∼14.0 ka, or approximately one third of global mean sea-level rise over this period. We determine 3.1–3.6 m of the saddle collapse meltwater was released during Meltwater Pulse 1A ∼14.6-14.3 ka, constituting 20–40% of this meltwater pulse's volume. Because the separation of the Cordilleran and Laurentide ice sheets occurred over 1–2 millennia, the associated release of meltwater during the saddle collapse supplied a smaller contribution to the magnitude of Meltwater Pulse 1A than has been recently proposed.
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Journal articleLarge SJE, Nathwani CL, Wilkinson JJ, et al., 2024,
Tectonic and crustal processes drive multi-million year arc magma evolution leading up to porphyry copper deposit formation in central Chile
, Journal of Petrology, ISSN: 0022-3530<jats:title>Abstract</jats:title> <jats:p>Subduction zone magmatism is a major control of volcanism, the generation of modern continental crust and the formation of economically important porphyry Cu-(Mo-Au) deposits. Reading the magmatic record of individual arc segments, and constraining the rates of magmatic changes, are critical in order to fully understand and quantify the processes that drive magma evolution in subduction settings during arc growth. This study focuses on the San Francisco Batholith and the Rio Blanco-Los Bronces porphyry deposit cluster in central Chile, which provides an igneous rock record over ~13.5 Myr of arc evolution. We use whole-rock geochemistry, zircon geochronology and Hf-isotope geochemistry to track changes in the crustal magmatic system of this arc segment during crustal thickening and porphyry Cu deposit formation. By combining the analytical dataset with Monte Carlo fractional crystallisation and assimilation fractional crystallisation modelling, we test a model for significant crustal involvement during magma evolution. Systematic and continuous increases in Dy/Yb, La/Yb, V/Sc and Sr/Y in the magmas over time indicate a transition in the main fractionation assemblage from plagioclase-dominated to amphibole-dominated that reflects deeper crystallisation and/or a higher melt water content. Concomitant decreases in εHf and Th/La as well as increasing Ba/Th are best explained by assimilation of progressively deeper crustal lithologies from low (Chilenia) to high Ba/Th (Cuyania) basement terranes. Our study highlights that an increasingly hydrous magma and a deepening locus of crustal magma differentiation and assimilation, driven by crustal thickening contemporaneous with increased tectonic convergence and ingression of the aseismic Juan Fernandez ridge, can account for all investigated aspects of the multi-Myr magmatic evolution leading up to the formation of the Rio Blanco-Los Bronces porp
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Journal articleGriffiths A, Lambelet M, Crocket K, et al., 2024,
Neodymium isotope composition and rare earth element distribution of East Antarctic continental shelf and deep waters
, Chemical Geology, ISSN: 0009-2541 -
OtherMurray-Watson R, Gryspeerdt E, 2024,
Air mass history linked to the development of Arctic mixed-phase clouds
<jats:p>The development of clouds during marine cold-air outbreaks (MCAOs) represent a complex phenomenon, transitioning from stratocumulus decks near ice edges to cumuliform fields downwind. This change cloud morphology changes the radiative properties of the cloud, and therefore is of importance to the surface energy budget. Therefore, it is crucial to understand the factors which may drive transition to a broken cloud field. Previous in situ and modelling studies suggest the formation of ice may enhance precipitation and therefore accelerate break-up. However, little is known about the development of mixed-phase clouds in MCAOs.&#160;This study uses pseudo-Lagrangian trajectories and satellite data to analyze this mixed-phase cloud development. We observe a rapid transition from liquid to ice phases in MCAO clouds, contrasting with similar cloud formations outside MCAO conditions. These mixed-phase clouds initially form at temperatures below -20&#176;C near ice edges but can dominate even at -13&#176;C further into outbreaks. This temperature shift suggests a significant role for biological ice nucleating particles (INPs), which increase in prevalence as air masses age over marine environments. The study also notes the influence of the air mass's history over snow- and ice-covered surfaces, which may be low in INPs, on cloud evolution. This link helps explain seasonal variations in Arctic cloud development, both during and outside of MCAOs. Our findings emphasize the importance of understanding local marine aerosol sources and the broader INP distribution in the Arctic for accurate cloud phase modeling in the region.&#160;</jats:p>
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OtherHoward B, Awuni C, Berkhout F, et al., 2024,
Co-production could improve the science-policy-practice nexus in hydrology: lessons from co-producing knowledge on flood risk in Tamale, Ghana
<jats:p>Understanding of hydrological risk is increasing but much of it remains non-actionable. Consequently, interventions are seldom informed by the latest insights, limiting their effectiveness and resilience, especially in a non-stationary world. The co-production of knowledge in hydrology can result in more salient, useful, and usable outcomes that are used to directly inform decisions. Co-production is an interactive and complex process founded on relationships between science, society, practice, and policy. We are applying this approach to generate locally relevant understanding, evidence, and action on flood risk in Tamale, a city of ~500,000 people in northern Ghana. A team of citizens, practitioners, policy makers, and researchers from a range of disciplines are working together to understand the drivers and distribution of flood risk, as well as the effects of top-down and citizen-led adaptation. Knowledge is generated and validated in a series of stages and cycles and operationalized in different modes for different users. Whilst this is an ongoing process which continues to evolve, in this talk I will share lessons and experiences from the co-production approach in Tamale that may be translatable to other contexts. Co-production approaches represent tangible frameworks to improve the science-policy-practice nexus in hydrology and water resources management, and sharing good examples can expedite adoption.</jats:p>
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OtherPonsonby J, Teoh R, Stettler M, 2024,
Towards an improved treatment of (semi) volatile particle activation in contrail models
<jats:p>Contrails are estimated to account for the majority of the present-day warming by the aviation industry. Their formation relies on the availability of aerosol in the exhaust plume, upon which water vapour can condense and subsequently freeze to form contrail ice crystals Most modern aircraft operate in the soot-rich regime, releasing soot particles with a number emission index (EIn) of between 1014 and 1016 (kg-fuel)-1. Under these conditions, the number concentration of soot particles and contrail ice crystals scales linearly. For this reason, existing global contrail simulations typically assume that the number concentration of ice crystals and soot particles are equivalent. However, the use of alternative fuels such as sustainable aviation fuel (SAF) and liquid hydrogen, and the adoption of cleaner lean-burn combustors in the existing fleet are likely to drive the soot EIn into the soot-poor regime < 1013 (kg-fuel)-1. Here, (semi) volatile material and entrained ambient particles can compete with soot for plume supersaturation and the relationship between the number concentration of soot particles and contrail ice crystals is non-linear. These effects are not currently accounted for in existing contrail models used to simulate regional and global contrail climate forcing. &#160;In this work, we extend the parcel model proposed by K&#228;rcher et al. [1] to account for the activation of volatile particulate matter (vPM) in the soot-poor regime and integrate this into the contrail cirrus prediction model (CoCiP) [2]. We explore the relationship between the soot EIn and the apparent ice emissions index (AEI) in the soot-rich and soot-poor regimes, evaluating the model&#8217;s sensitivity to different aerosol properties, including particle hygroscopicity and characteristics of the particle size distribution. Preliminary results show a linear relationship between the soot EIn and AEI in the soot-rich regime, consistent with
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OtherPrasow-Émond M, Plancherel Y, Mason PJ, et al., 2024,
Impacts of Climate Change on Small Island Nations: A Data Science Framework using Remote Sensing and Observational Time Series
<jats:p>Small Island Developing States (SIDS) comprise a group of 58 nations identified by the United Nations as facing unique sustainability challenges. These challenges include high exposure to climate change and a lack of data and limited resources. The effects of climate change are already observed in SIDS, notably an increase in the magnitude and frequency of natural disasters, biodiversity loss, ocean acidification, coral bleaching, sea-level rise, and coastal erosion. The coastal zone is considered to be the main economic, environmental, and cultural resource of SIDS, making them particularly vulnerable to the adverse effects of climate change. This project focuses on quantifying&#160;and disentangling coastal changes, including erosion, accretion and coastline stability. Existing literature lacks a comprehensive understanding of the patterns of coastal changes, as well as the main anthropogenic and environmental drivers involved. We&#160;address this research gap by quantifying the challenges that SIDS encounter, with a particular emphasis on coastal changes.The approach is data-driven, relying on observational time series extracted from remote sensing (e.g., Sentinel-2, Planet Scope, Landsat missions), in situ measurements (e.g., tide gauge data), and open-access databases. We have developed a robust method based on image segmentation to extract the island's shape over time, enabling us to illustrate the island's dynamics and obtain reliable time series of the coastline position.&#160;The main drivers of coastal changes are then identified and quantified using time series analysis methods, including causal inference and discovery methods, for SIDS worldwide. We place a specific focus on the Maldives (Indian Ocean) due to its low elevation and high human activity. Additionally, the methodology expands to investigate a spectrum of issues, including the impacts of human activities (e.g., land reclamation, sand mining, shoreline ar
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OtherHorner G, Gryspeerdt E, 2024,
How does the lifetime of cirrus detrained from deep convection impact the cloud radiative effect of the tropics?
<jats:p>Large cirrus outflows detrained from deep convection play a vital role in modulating the radiative balance of the Earth&#8217;s atmosphere. The total cloud radiative effect (CRE) in the tropics is close to zero due to a cancellation between a large shortwave (SW) cooling from optically thick clouds and a longwave (LW) warming from high-altitude thin cirrus that spread over much of the tropics. Any small percentage changes to the LW or SW components of these large detrained cirrus in a future climate could, therefore, have significant impacts on the overall CRE in the tropics.A crucial question is how the lifetime of these detrained cirrus impacts the total cloud radiative effects in the tropics. Characterising the detrained cirrus outflows, how they evolve over time, and how they might change in a future climate is vital in order to understand their role in the climate system and to constrain past and future climate change.Building on the &#8216;Time Since Convection&#8217; product used in Horner &amp; Gryspeerdt (2023), this work investigates how the initial conditions of deep convection influence the radiative evolution and lifetime of the detrained cirrus. If we extend the lifetime of detrained cirrus, how does this change their total radiative effect and the radiative balance in the tropics? To answer this question, data from the DARDAR, ISCCP, and CERES products are used to build a composite picture of the radiative and microphysical properties of the clouds, which are investigated under varying initial conditions.It is found that the initial conditions of the convection, in particular whether the convection occurs over land or ocean, play an important role in determining the lifetime and total CRE of the detrained cirrus clouds, due to the strong diurnal contrasts in convection over ocean and land. Furthermore, it is found that artificially extending the lifetime of the detrained cirrus increases the total CRE of h
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