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Expanding the Yukon tree ring blue intensity network to assess divergence effects and enhance climate reconstructions
Get PDFFunding: This work was supported by a PhD Scholarship from the Carnegie Trust for the Universities of Scotland and the ERC Advanced Grant ‘Monostar’ [AdG 8822727]. NSF OPP 2124885. Collaborative Research: Tracking Divergent Warming and Tree Growth at Arctic Treeline. NSF Arctic Social Science grant 2112314, Collaborative Research: Understanding the Impacts of Extreme Events on the Peoples of the Arctic.The Divergence Problem (DP) – classically defined as a breakdown in the relationship between tree growth and temperature in recent decades – poses a major challenge to developing robust tree-ring based climate reconstructions. This is particularly relevant in northwestern North America (NWNA), a climatically sensitive yet underrepresented region in dendroclimatological networks. To address this gap and the implications of the DP, we developed a network of 34 white spruce sites across southern and central Yukon, using latewood Blue Intensity (LWBI) as a high-resolution proxy for maximum summer temperatures. Sites span a broad elevational range, allowing assessment of how proximity to local treeline influences climate sensitivity. LWBI chronologies from sites within 100 m of upper treeline exhibit the strongest (r2 = 0.46) and most temporally stable relationship with June-August (JJA) temperatures. In contrast, lower elevation chronologies display weaker coherence and declining sensitivity in the recent period that is consistent with the DP. Ring width chronologies express poor correlations and temporal stability and are not recommended for temperature reconstructions in this region. Despite near-treeline LWBI sites presenting the best option for optimising reconstructions, there is slight evidence of a non-linear relationship between LWBI and JJA temperatures, leading to the underrepresentation of extreme warm summer temperatures. The results herein offer a strategy for minimising the DP and enhancing the reliability of temperature reconstructions in NWNA through targeted site selection. However, in a warming world, a progressive weakening in temperature limitation – even at optimal sites – will likely lead to a degradation in calibration accuracy in future reconstructions.Peer reviewe
Correction: Square array designs for unreplicated test treatments with replicated controls
Get PDFThese are mistakes which occurred in the type-setting process.Non peer reviewe
When the shadow of death fell upon us : Covid-19, the UK Government, and my mother
Get PDFOn Thursday 12 February 2021, my mother died of Covid-19. The focus of this article are the days leading up to and after her death. Whilst deeply personal, it is intensely political. The article critiques the actions and inactions of the United Kingdom (UK) government’s handling of the pandemic. It is written in light of the Sue Gray Report (2022) and initial evidence from the ongoing UK Covid-19 Inquiry. In today’s ‘post-pandemic’ world, where there has been no public mourning or grieving, people are just expected to carry their grief and loss through time and space. Away from the officialdom and the Covid-19 death statistics, this article tells the real life-story of the complex interplay between politics, faith, illness, death, and grief. I adopt an auto/biographical approach to provide an intimate insight into how my mother and the family prepared for and understood her death. I explore how my mother’s faith enabled her to come to terms with her own mortality by, in part, ensuring that everything continued as she wanted it to. The article also discusses the challenges of completing ‘symbolic enactments’ that are integral to memorialisation, which were prohibited during the pandemic.Peer reviewe
The date and context of the Astronomer's 'Life of Louis the Pious'
Get PDFThe Astronomer's Life of the emperor Louis the Pious (814–40) is a canonical source for scholars of Frankish history. It sits at the centre of recent debates about the nature and tone of Carolingian political discourse, and about the crisis of the empire in the 830s. Yet the date and precise context of the text's composition have hardly ever been debated. The consensus position, codified in Ernst Tremp's definitive 1995 edition, is that it was written very shortly after the death of its subject, during the succession war fought between his sons. In this article I argue that this reading is not as secure as is usually assumed, and that a later dating may be preferable. I propose a new interpretation of the text as a product of Charles the Bald's reign and argue that this context reinvigorates the Life's value as a source for ninth-century history.Peer reviewe
Effect of numerical resolution on synthetic observables of simulated coronal loops
Get PDFFunding: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 101097844). The authors gratefully acknowledge the computational resources provided by the Cobra supercomputer system of the Max Planck Computing and Data Facility (MPCDF) in Garching, Germany. The research leading to these results has received funding from the UK Science and Technology Facilities Council (consolidated grant ST/W001195/1). Ineke De Moortel received funding from the Research Council of Norway through its Centres of Excellence scheme, project number 262622. CHIANTI is a collaborative project involving George Mason University, the University of Michigan (USA), University of Cambridge (UK) and NASA Goddard Space Flight Center (USA).Increasingly realistic simulations of the corona are used to predict synthetic observables for instruments onboard both existing and upcoming heliophysics space missions. Synthetic observables play an important role in constraining coronal heating theories. Choosing the spatial resolution of numerical simulations involves a trade-off between accuracy and computational cost. Since the numerical resolution affects not only the scale of structures that can be resolved, but also thermodynamic quantities such as the average coronal density, it is important to quantify the effect on synthesized observables. Using 3D radiative magnetohydrodynamic simulations of coronal loops at three different grid spacings, from 60 km down to 12 km, we find that changes in numerical resolution lead to differences in thermodynamic quantities and stratification as well as dynamic behaviour. Higher grid resolution results in a more complex and dynamic atmosphere. The resolution affects the emission intensity as well as the velocity distribution, thereby affecting synthetic spectra derived from the simulation. The distribution of synthetic coronal loop strand sizes changes as more fine-scale structure is resolved. A number of parameters, however, seem to start to saturate from our chosen medium grid resolution on. Our study shows that while choosing a sufficiently high resolution matters when comparing forward-modelled observables with data from current and future space missions, for most purposes not much is gained by further increasing the resolution beyond a grid spacing of 24 km, which seems to be adequate for reproducing bulk loop properties and forward-modelled emission, representing a good trade-off between accuracy and computational resource.Peer reviewe
Stratospheric dayside-to-nightside circulation drives the 3D ozone distribution on synchronously rotating rocky exoplanets
Get PDFFunding: MB, PIP, and LD are part of the CHAMELEON MC ITN EJD which received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 860470. PIP acknowledges funding from the STFC consolidator grant no. ST/V000594/1. LD acknowledges support from the KU Leuven IDN grant IDN/19/028 and from the FWO research grant G086217N. MC acknowledges the funding and support provided by the Edinburgh Earth, Ecology, and Environmental Doctoral Training Partnership and the Natural Environment Research Council (grant no. NE/S007407/1). NJM was supported by a UKRI Future Leaders Fellowship (grant no. MR/T040866/1), a Science and Technology Facilities Council consolidated grant (ST/R000395/1), and the Leverhulme Trust through a research project grant (RPG-2020-82).Determining the habitability and interpreting future atmospheric observations of exoplanets requires understanding the atmospheric dynamics and chemistry from a 3D perspective. Previous studies have shown significant spatial variability in the ozone layer of synchronously rotating M-dwarf planets, assuming an Earth-like initial atmospheric composition. We simulate Proxima Centauri b in an 11.2-d orbit around its M-type host star using a 3D coupled climate-chemistry model to understand the spatial variability of ozone and identify the mechanism responsible for it. We document a previously unreported connection between the ozone production regions on the photochemically active dayside hemisphere and the nightside devoid of stellar radiation and thus photochemistry. We find that stratospheric dayside-to-nightside overturning circulation can advect ozone-rich air to the nightside. On the nightside, ozone-rich air subsides at the locations of two quasi-stationary Rossby gyres, resulting in an exchange between the stratosphere and troposphere and the accumulation of ozone at the gyre locations. The mechanism drives the ozone distribution for both the present atmospheric level (PAL) and a 0.01 PAL O2 atmosphere. We identify the hemispheric contrast in radiative heating and cooling as the main driver of the stratospheric dayside-to-nightside circulation. An age-of-air experiment shows that the mechanism also impacts other tracer species in the atmosphere (gaseous and non-gaseous phase) as long as chemical lifetimes exceed dynamical lifetimes. These findings, applicable to exoplanets in similar orbital configurations, illustrate the 3D nature of planetary atmospheres and the spatial and temporal variability that we can expect to impact spectroscopic observations of exoplanet atmospheres.Peer reviewe
Amplifying immersive climate learning
Get PDFClimate change poses an existential threat to our heritage and the way we live, yet its impacts are still often perceived as distant, which in turn acts as a barrier to achieving the behavioural and societal changes required to solve this emergency. This paper summarises impacts of climate change, psychological barriers to effective action, and how experiential climate learning can help overcome these challenges. Surveys of community perceptions of threats to cultural and natural heritage in Scotland’s Western Isles, and the increasing engagement of heritage practitioners with this emergency point to the power of heritage as a positive actor in the climate crisis. A strategy for using virtual reality to extend experiential climate learning is proposed and evaluated through the creation and deployment of a climate heritage exhibit. The exhibit enables climate impacts and potential climate futures for the Western Isles to be experienced. The workflow used is then applied to global landscapes experiencing climate change. This demonstrates the way that virtual reality can represent the diversity of landscapes impacted by this crisis and enable immersive climate learning experiences
A protocol for the ERICA-ARREST feasibility study of Emergency Resuscitative Endovascular Balloon Occlusion of the Aorta in Out-of-Hospital Cardiac Arrest
Get PDFFunding: The research costs of the study are part-funded by the Rosetrees Trust, with reimbursement of excess treatment costs from the Department of Health & Social Care and study support costs from the East of England Clinical Research Network (National Institute of Health Research). Donations towards development and set-up of the study were also received from the Dowager Countess Elanor Peel Trust (DCEPT), The Charles Wolfson Charitable Trust, The Thriplow Charitable Trust, and The Helen Roll Charity.Background Fewer than one in ten out-of-hospital cardiac arrest (OHCA) patients survive to hospital discharge in the UK. For prehospital teams to improve outcomes in patients who remain in refractory OHCA despite advanced life support (ALS); novel strategies that increase the likelihood of return of spontaneous circulation, whilst preserving cerebral circulation, should be investigated. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) has been shown to improve coronary and cerebral perfusion during cardiopulmonary resuscitation. Early, prehospital initiation of REBOA may improve outcomes in patients who do not respond to standard ALS. However, there are significant clinical, technical, and logistical challenges with rapidly delivering prehospital REBOA in OHCA; and the feasibility of delivering this intervention in the UK urban–rural setting has not been evaluated. Methods The Emergency Resuscitative Endovascular Balloon Occlusion of the Aorta in Out-of-Hospital Cardiac Arrest (ERICA-ARREST) study is a prospective, single-arm, interventional feasibility study. The trial will enrol 20 adult patients with non-traumatic OHCA. The primary objective is to assess the feasibility of performing Zone I (supra-coeliac) aortic occlusion in patients who remain in OHCA despite standard ALS in the UK prehospital setting. The trial’s secondary objectives are to describe the hemodynamic and physiological responses to aortic occlusion; to report key time intervals; and to document adverse events when performing REBOA in this context. Discussion Using compressed geography, and targeted dispatch, alongside a well-established femoral arterial access programme, the ERICA-ARREST study will assess the feasibility of deploying REBOA in OHCA in a mixed UK urban and rural setting.Peer reviewe
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