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Recognition of loss & damage from wildfires is key for climate justice [Comment]
Get PDFWildfires are becoming one of the defining climate-related crises of the twenty-first century. We argue that their inclusion in the Loss & Damage framework of the United Nations Framework Convention on Climate Change is essential to support prevention, recovery and justice for the most affected communities
Solar Wind and Geomagnetic Conditions That Lead to the Largest Relativistic Electron Fluxes in GPS Orbit
Get PDFRelativistic electrons are an important space weather hazard, being a major source of radiation
damage to satellites and posing a risk to humans in space. We use approximately 20 years of data from the
US Global Positioning System (GPS) satellite NS41 to determine the characteristics of the geomagnetic
storms that lead to the largest relativistic electron fluxes in GPS orbit. The largest coronal mass ejection
(CME)‐driven events are associated with the solar wind having negative excursions of the IMF Bz with
minimum values of ∼−14 nT two hours prior to zero epoch, defined as the time of the minimum in the Dst
index, and strong Dst minima, reaching ∼−130 nT at zero epoch. In contrast, events driven by high speed
solar wind streams (HSSs) are associated with smaller negative excursions of IMF Bz with minimum values
of ∼−4 nT one to two hours prior to zero epoch and moderate Dst minima, reaching ∼−60 nT at zero
epoch. Compared with HSS‐driven events, peak E = 2.0 MeV fluxes associated with CME‐driven events
are larger by factors of 1.3 at L = 4.5 and 2.4 at L = 6.5. Both the CME‐ and HSS‐driven events are
associated with enhancements in the solar wind number density and pressure prior to zero epoch. Following
zero epoch the solar wind number density and pressure become low and substorm activity is enhanced for
several days
Chapter 11 - Southern Annular Mode
No full textThe Southern Annular Mode (SAM) is an important pattern of Southern Hemisphere circulation variability: it accounts for between 15 and 30 or more percent of the total variability of the Southern Hemisphere extratropical circulation on daily to annual time scales and significantly modulates weather variability across the middle and higher latitudes. It is an expression of feedback between the mean westerly flow over the Southern Ocean and its associated storm track. The discovery in the late 1990s of a trend in SAM behavior led to the realization that stratospheric ozone depletion and greenhouse gas increase both influence SAM behavior, and will do through coming decades. This chapter surveys the mechanism of the SAM, the history of our understanding of the SAM, its impacts upon surface climate, and the outlook for the SAM’s future
Refined climatologies of future precipitation over High Mountain Asia using probabilistic ensemble learning
Get PDFHigh Mountain Asia (HMA) holds the highest concentration of frozen water outside the polar regions, serving as a crucial water source for more than 1.9 billion people. Precipitation represents the largest source of uncertainty for future hydrological modelling in this area. In this study, we propose a probabilistic machine learning framework to combine monthly precipitation from 13 regional climate models developed under the Coordinated Regional Downscaling Experiment (CORDEX) over HMA via a mixture of experts (MoE). This approach accounts for seasonal and spatial biases within the models, enabling the prediction of more faithful precipitation distributions. The MoE is trained and validated against gridded historical precipitation data, yielding 32% improvement over an equally-weighted average and 254% improvement over choosing any single ensemble member. This approach is then used to generate precipitation projections for the near future (2036–2065) and far future (2066–2095) under RCP4.5 and RCP8.5 scenarios. Compared to previous estimates, the MoE projects wetter summers but drier winters over the western Himalayas and Karakoram and wetter winters over the Tibetan Plateau, Hengduan Shan, and South East Tibet
One Biosecurity is essential to implement One Health
Get PDFAlthough One Health and biosecurity both aim to protect the health of people, animals, and ecosystems from biological hazards, the two fields remain heavily siloed across distinct policy and research domains. One Health has yet to fully integrate environmental perspectives, especially biological invasions, into its workplan, whereas biosecurity lacks an effective inclusion of the social and health sciences, further hindering collaboration. One Biosecurity offers a vital interdisciplinary framework that bridges human, animal, plant, and ecosystem health sectors, fostering a stronger connection between biosecurity and One Health. This comprehensive approach spans the entire biosecurity continuum, from pre-border intelligence scans to border inspections and post-border incursion management, enabling more effective responses to the threats posed by biological invasions. By unifying these efforts, One Biosecurity will engage a broader group of multilateral organizations, bring together diverse stakeholders, and implement balanced strategies that better safeguard human health, agriculture production systems, and the natural environment
OneSTOP: OneBiosecurity systems and technology for people, places and pathways [Grant proposal]
Get PDFThe overarching objective of OneSTOP is to pioneer an innovative and joined-up approach to biosecurity for terrestrial invasive alien species, strengthening the interconnections between animal, plant, human and environmental health. OneSTOP aims to harness current technologies and citizen science, while overcoming challenges posed by dispersed and fragmentary processes, policies, and knowledge, to deliver methods for identification, early detection and surveillance of invasive alien species. OneSTOP aims to achieve transformative results to minimise the introduction, establishment and spread of invasive alien species by integrating cutting-edge detection methods, underpinned by prioritisation and robust models, alongside stakeholder engagement to inform harmonised policies and facilitate knowledge exchange. The outcomes will be relevant for invasive alien species policy, noting the importance of enhancing collaboration and coordination across local, national, and regional scales, recognising that geographic boundaries do not confine the impact of these species. By adopting a holistic and interconnected approach, OneSTOP seeks to establish a strategy to achieve rapid and transformative progress in detecting, eradicating and controlling invasive alien animals and plants, ultimately contributing to a more secure and resilient environment. Throughout, OneSTOP is based upon the strategic actions recommended for integrated governance of biological invasions in the recently published IPBES Thematic assessment report on invasive alien species and their control (IPBES 2023)
Ecosystem metabolism and nitrogen budget of a glacial fjord in the Arctic (Kongsfjorden)
Get PDFFjords in the Arctic are changing rapidly due to multiple factors including increasing air temperatures, the influx of Atlantic Water (Atlantification), sea-ice loss, retreat of tidewater glaciers, increased freshwater discharges, pollution and tourism. Understanding how these changes affect ecosystem processes and functions and, thus, services to society is critical. Net Ecosystem Metabolism (NEM) offers a holistic measure of ecosystem functioning and services, reflecting the balance between autotrophic and heterotrophic processes and the sink/source role of an ecosystem for nutrients and carbon. Using a 10-year dataset we quantify the main nutrient sources and sinks in Kongsfjorden (Svalbard) and estimate NEM using a method based on mixing diagrams combined with an ocean circulation model. We show that Kongsfjorden is a nutrient and carbon sink primarily supported by nutrient inputs from the adjacent shelf sea with terrestrial run-off playing a secondary role. Given the ongoing changes in the Arctic, driven by global warming and its associated effects, we recommend monitoring NEM as an integrated measure of the state of coastal ecosystems, considering the disproportionately large role of coastal regions in the global carbon budget
West Antarctic ice retreat and paleoceanography in the Amundsen Sea in the warm early Pliocene
Get PDFMass loss from polar ice sheets is poorly constrained in estimates of future global sea-level rise. Today, the marine-based West Antarctic Ice Sheet is losing mass at an accelerating rate, most notably in the Thwaites and Pine Island glacier drainage basins. Early Pliocene surface temperatures were about 4 °C warmer than preindustrial and maximum sea level stood ~20 m above present. Using data from a sediment archive on the Amundsen Sea continental rise, we investigate the impact of prolonged Pliocene ocean warmth on the ice-sheet−ocean system. We show that, in contrast to today, during peak ocean warming ~4.6 − 4.5 Ma, terrigenous muds accumulated rapidly under a weak bottom current regime after spill-over of dense shelf water with high suspended load down to the rise. From sediment provenance data we infer major retreat of the Thwaites Glacier system at ~4.4 Ma several hundreds of km inland from its present grounding line position, highlighting the potential for major Earth System changes under prolonged future warming
Brief communication: Reduced bandwidth improves the depth limit of the radar coherence method for detecting ice crystal fabric asymmetry
Get PDFIce crystal orientation fabric strongly affects the viscous deformation of glacier ice. A popular technique to investigate ice fabric is radar polarimetry, often analysed using the coherence method. However, in fast-flowing areas with strong anisotropy, this method provides information of shallow areas below the surface only. This study proposes reducing radar bandwidth to enhance the depth limit for fabric asymmetry detection. Using data from two ice streams, we demonstrate that reduced bandwidth significantly increases the depth limit, depending on the centre frequency. This approach aims to improve the understanding of the spatial distribution of fabric, crucial for ice dynamics in fast-flowing regions
Impact of intertidal habitats on hydrodynamics in tidally energetic, well-mixed estuaries
No full textEstuarine intertidal habitats, which strongly affect the functioning of estuarine ecosystems, have rapidly diminished worldwide due to human activities and climate change. However, the mechanisms by which intertidal habitats modulate estuarine hydrodynamics remain poorly understood. A three-dimensional semi-analytical model is developed to systematically investigate the interactions between intertidal and channel waters in tidally dominated, well-mixed estuaries. By considering simplified bathymetry, geometry, and forcing conditions, the model dynamically couples intertidal and channel water motions using a perturbation method that allows for an explicit dissection of different controlling physical processes. Our findings reveal that intertidal habitats amplify semi-diurnal tidal motions, causing significantly enhanced residual and quarter-diurnal tidal currents due to advection (AC). The strengthened AC shifts the pattern and magnitude of the total residual circulation. Lateral water exchange between intertidal and channel regions generates a new residual and quarter-diurnal tidal contribution (TF), which dampens quarter-diurnal tidal currents in the deep channel. The TF and enhanced AC due to intertidal habitats increase ebb-dominance in the deep channel. Our sensitivity analysis shows that halving the intertidal width halves the water exchange and the above-mentioned intertidal effects on the residual and tidal currents, and the upper-estuary habitats induce broader changes in the channel hydrodynamics than lower-estuary habitats. We also found that increasing estuary length/convergence strongly affects the intertidal effects. These findings highlight the importance of understanding interactions between intertidal and channel waters to evaluate the risks of intertidal habitat loss for estuarine functioning and the potential benefits of intertidal habitat restoration/creation in mitigating estuarine hazards
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