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New integrations of U Pb zircon data from Caledonian intrusions in the Southern Uplands of Scotland
Get PDFThe Laurentian margin in Britain and Ireland experienced the Caledonian-Acadian orogenies resulting from Palaeozoic closure of the Iapetus Ocean and accretion of Baltica and peri-Gondwanan terranes. However, the age and significance of magmatism remain contested, without a geologically consistent geodynamic reconstruction. We have interrogated the Usingle bondPb zircon record of intrusive complexes within the Southern Uplands-Down-Longford accretionary complex, focused on the Southern Uplands in Scotland. New texturally constrained laser ablation data are presented from the Carsphairn, Black Stockarton Moor, Bengairn, and Cheviot complexes. In these locations, most zircons contain poorly zoned cores with 206Pb/238U ages no older than ∼ 424 Ma, chemically comparable with younger magmatic overgrowths. Magmatic overgrowth ages confirm emplacement of Carsphairn at ∼ 414–411 Ma, Black Stockarton Moor and Bengairn at ∼ 410–408 Ma, and Cheviot at ∼ 400 Ma. Across the accretionary complex, the onset of zircon growth from ∼ 424 Ma appears to mark slab roll-back processes. Zircon cores may represent stalling and crystallisation of magmas in the deep crust, whilst emplacement into the shallow crust after ∼ 415 Ma accompanies the onset of regional transtension. We do not feel there is sufficient evidence to directly attribute magmatism to slab breakoff, despite this process being popularly championed in Scottish and Irish geology. We discuss the latest geodynamic interpretations of magmatism during the Caledonian-Acadian events, including events to the south of the Iapetus suture, and argue that complete zircon histories have a role to play in reconstruction of ancient orogens
Global surface temperatures
Get PDFThe Sixth Assessment Report of the Intergovernmental Panel on Climate Change stated that ”it is unequivocal that human influence has warmed the atmosphere, ocean and land”. One key piece of evidence for this is the global average of the instrumental record of surface temperature. A change in surface temperature of 1.5˚C relative to a reference “pre-industrial” period is the measure internationally agreed to mark the transition to a climate where dangerous impacts become common. This chapter will discuss the observational evidence that ensures a reliable record of the changing temperature, some of the challenges that have been overcome, and some that remain in improving that record and more fully understanding its uncertainty
Spatio-temporal changes in interannual sea level along the world coastlines
Get PDFTo investigate how coastal sea level evolves at interannual time scales from one region to another, we perform an Empirical Orthogonal Function (EOF) decomposition of coastal sea level time series derived from reprocessed coastal altimetry data over a 20-year long time span (2002−2021), at 1132 virtual coastal stations homogeneously distributed along the world coastlines. This analysis is first performed globally and then over selected coastal regions. Consistent with previous studies, the results show the dominant influence of internal climate modes, in particular ENSO (El Niño Southern Oscillation), on the interannual coastal sea level variability. But our study also reports novel findings in coastal sea level: (1) a regime shift between 2008 and 2012, with increased sea level rate after that date in many coastal regions, and (2) a 6-year cycle, notably along the northeast and northwest coasts of America (north of 40°N) and along the Indian coast of Indonesia. Additional EOF analyses are done using both gridded altimetry sea level data from the Copernicus Climate Change Service and an ensemble mean of four ocean reanalyses, in three successive coastal bands: 0-50 km, 50-100 km and 100-500 km from land. They confirm the strong influence of internal climate modes at the coast but also show that results in the cross-shore direction towards the open ocean are similar to those at the coast. This study based on three different datasets shows that the strong influence of internal climate modes on sea level interannual variability in the world coastal zones is not limited to the open ocean but also dominates sea level changes very close to the coast. It also shows evidence of a regime shift in the rate of change of coastal sea level between 2008 and 2012 and the presence of a 6-year oscillation in coastal sea level, possibly linked to the recent discovery of a 6-year cycle in the whole climate system
Wind‐Driven Iron Supply by Ekman Buoyancy Flux Enhances Phytoplankton Bloom in the Antarctic Circumpolar Current
Get PDFThe Southern Ocean today is a globally relevant sink for atmospheric carbon dioxide (CO2),
where the biological uptake of carbon through primary productivity is largely controlled by widespread iron
(Fe) limitation. We analyze observations from a submesoscale‐resolving cross‐section of the Antarctic
Circumpolar Current (ACC) obtained around one thousand kilometers downstream of South Georgia in
the Atlantic sector during austral spring 2022. Vertically integrated chlorophyll peaked in a strong
(∼250 mgChl‐a m− 2
) phytoplankton bloom within the central portion of the jet associated with the Southern
ACC Front. We infer that winds drove a northward Ekman transport of dense water across the front and that this
destabilized the water column, leading to an Ekman Buoyancy Flux (EBF) and enhanced vertical mixing
(∼ 1 × 10− 2 m2 s
− 1
) across the base of the mixed layer. Using in situ measurements of dissolved iron, we
estimate a net flux to the bloom of up to 3 μmolFe m− 2
d‒1 from a subsurface pool. This large flux can supply the
same amount of Fe per unit area in one day as that supplied to the upstream Georgia Basin bloom through deep
wintertime entrainment in 1 year. We calculate the bloom's daily Fe demand from in situ 55Fe uptake
measurements by phytoplankton and find it to be of a similar order of magnitude as the EBF‐driven supply. We
conclude that the bloom's strength and compact latitudinal extent are explained by EBF. Thus, EBF represents a
previously understudied mechanism, which contributes to bloom patchiness and modulates biologically
mediated CO2 drawdown in the iron‐limited Southern Ocean
Structural controls on pressure communication across the Bunter Sandstone Formation, UK Southern North Sea
Get PDFThe utilization of extensive saline aquifers for CO 2 storage will require careful consideration of the potential pressure responses. The displacement of formation waters results in far-reaching pressure footprints that extend beyond the storage sites. Where multiple storage projects share a connected saline aquifer, the available pressure budgets for neighbouring projects may be negatively impacted. Structures such as faults and salt walls can potentially divide an aquifer into smaller hydraulic units.
The extent of hydraulic units in the Bunter Sandstone Formation (BSF) within the UK Southern North Sea (UKSNS) was investigated by structural interpretation of seismic data. A new classification scheme was developed to characterize the major structural features affecting the BSF and their likely impact on boundary conditions. The resultant boundary condition map indicates where structures are expected to inhibit pressure communication through displacement/dislocation of the BSF aquifer. The results were validated by pressure data, which confirmed the existence of variable pressure regimes across the BSF.
Understanding these boundary conditions is essential to support the strategic deployment of CO 2 storage in the UKSNS and to maximize storage capacity. The methodology can also be applied to other regions where extensive saline aquifers are considered for CO 2 storage
Detecting and mapping invasive species across riparian corridors via object detection approaches in UAV imagery: an example of Impatiens glandulifera
Get PDFRiparian zones in the United Kingdom have high species diversity but are prone to anthropogenic changes and alien plant invasions, like Impatiens glandulifera . However, identification can be challenging due to poor accessibility or visibility via tree canopies. UAVs provide a means to access previously inaccessible areas and capture imagery of the area. In this study, a method is introduced to identify the flowers of invasive species ( Impatiens glandulifera ) and map their locations using a computer vision framework and oblique image capture methods. The process includes thresholding images, image masking, blurring, ellipsoid shape search, noise reduction, and contour extraction. Locations are determined using camera parameters, EXIF data, and the average flower size, then converted into vector format for GIS software. This method is wrapped into a single executable program named the semi‐automatic thresholding tool (SATT). A validation set of 312 UAV images from the River Elwy, North Wales, showed high precision (79%–96%) and mean average precision (mAP) scores of 73%–86%. This demonstrates that the SATT consistently and correctly identifies Impatiens glandulifera flowers from UAV imagery, making it effective for identifying hotspots and targeting management techniques along riparian corridors. The tool has been wrapped into a single‐file executable program with a graphical user interface, enabling nonexperts to use the tool without the need of any software installation. Overall, the tool obtains consistent detection levels of abundance/or flower density across the study site. The tool also does not require an extensive amount of training data, and the intuitive design of the software enables nonexperts to utilize the tool and modify parameter values to adapt it to their needs
Spatiotemporal faunal connectivity across global seafloors
No full textOur knowledge of biogeographic patterns and processes in the deep sea has been limited by the lack of integrated datasets that cover its vast extent1. Here we analyse a new global dataset of genomic DNA sequences, spanning an entire taxonomic class of benthic invertebrates (Ophiuroidea), to obtain a broad understanding of phylogenetic divergence and biotic movement across all oceans, from coastal margins down to the abyssal plains. We show that regional faunas on the continental shelf are phylogenetically divergent, particularly at temperate and tropical latitudes. By contrast, assemblages in the deep sea are much more connected. Many temperate deep-sea lineages have achieved distribution ranges across the planet, including over the Quaternary period. A close relationship exists between deep-sea faunas of the northern Atlantic and, on the opposite side of the globe, southern Australia. Bathymetric interchange is not only reliant on vertical migration through isothermal polar waters but also occurs across the thermal depth gradients of tropical regions. The connected nature of deep-sea life should be an important consideration in marine conservation assessment
Where do we want the glaciological community to be in 2073? EDI challenges and visions from the 2023 Karthaus Summer School
Get PDFDespite the increased awareness and action towards Equality, Diversity, and Inclusion (EDI), the glaciological community still experiences and perpetuates examples of exclusionary and discriminatory behavior. We here discuss the challenges and visions from a group predominantly composed of early-career researchers from the 2023 edition of the Karthaus Summer School on Ice Sheets and Glaciers in the Climate System. This paper presents the results of an EDI-focused workshop that the 36 students and 12 lecturers who attended the summer school actively participated in. We identify common threads from participant responses and distill them into collective visions for the future of the glaciological research community, built on actionable steps toward change. In this paper, we address the following questions that guided the workshop: What do we see as current EDI challenges in the glaciology research community and which improvements would we like to see in the next fifty years? Contributions have been sorted into three main challenges we want and need to face: making glaciology (1) more accessible, (2) more equitable, and (3) more responsible
The genome sequence of the tortix moth, Archips podanus (Scopoli, 1763)
Get PDFWe present a genome assembly from a male specimen of Archips podanus (Tortix moth; Arthropoda; Insecta; Lepidoptera; Tortricidae). The genome sequence has a total length of 549.00 megabases. Most of the assembly (99.72%) is scaffolded into 30 chromosomal pseudomolecules, including the Z sex chromosome. The mitochondrial genome has also been assembled, with a length of 15.45 kilobases
What is a drought-to-flood transition? Pitfalls and recommendations for defining consecutive hydrological extreme events
Get PDFResearch into rapid transitions between hydrological drought and flood is growing in popularity, in part due to media-reported catastrophic impacts from recent events. Droughts and floods are typically studied as events that are independent from one another. Thus, a clear definition and assessment of the methods used to define consecutive drought-to-flood transition events does not yet exist. Here, we use a series of eight catchments that have experienced real-world impacts from drought-to-flood transitions as case studies. We assess the suitability of and differences between event selection methods applied to observational data. We demonstrate that different threshold level methods can alter the characteristics of selected events. The number and timing of transitions differs substantially between threshold level approaches in highly seasonal regimes as opposed to those with a weaker seasonality. The time period used to define the maximum interval between drought and flood also influences whether transitions are detected. We show that the probability of a transition occurring within a set time window could vary substantially between different methodologies and catchments. We also show that previously applied methodologies would likely fail to detect transition events that have been broadly impactful in the historical record. For the eight case study events taken from media, governmental and scientific reports, only three of the transitions were successfully detected. We qualitatively assessed the streamflow time series of the case study catchments, and outline a number of potential pitfalls in the event detection process. Finally, we make recommendations regarding methodological choices in the context of potential impacts of interest, and outline some priorities for future methodological development and research
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