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Mass loss from the West Antarctic Ice Sheet is dominated by glaciers draining into the Amundsen Sea Embayment (ASE). The majority of that mass loss is driven by decadal variations in submarine melt rates. However, periods of extremely high or low precipitation can compound or mitigate ocean-driven mass losses, yet the impact of anomalous precipitation on the mass balance of the ASE is poorly known. We present a 25-year (1996-2021) record of ASE input-output mass balance and evaluate how two periods of anomalous precipitation affected its sea level contribution. Since 1996, the ASE has lost 3331±424 Gt ice, contributing 9.2±1.2 mm to global sea level. Overall, surface mass balance changes contributed just 7.7 % to total mass loss; however, two anomalous precipitation events had a larger, albeit short-lived, impact on rates of mass change. During 2009-2013, persistently low snowfall, due to anomalously zonal circulation, led to an additional 51±4 Gt yr-1 mass loss in those years (contributing positively to the total loss of 195±4 Gt yr-1). Contrastingly, extreme precipitation in the winters of 2019 and 2020 decreased mass loss by 60±16 Gt yr-1 during those years (contributing negatively to the total loss of 107±15 Gt yr-1). These results demonstrate that extreme snowfall variability can have a substantial impact on the short-term sea level contribution from West Antarctica and show that mass changes do not necessarily scale with grounding line discharge anomalies.

Satellite-based earth observation sensors are increasingly able to monitor geophysical signals related to natural hazards, and many groups are working on rapid data acquisition, processing, and dissemination to data users with a wide range of expertise and goals. A particular challenge in the meaningful dissemination of Interferometric Synthetic Aperture Radar (InSAR) data to non-expert users is its unique differential data structure and sometimes low signal to noise ratio. In this study, we evaluate the online dissemination of ground deformation measurements from InSAR through Twitter, alongside the provision of open access InSAR data from the Centre for Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET) Looking Into Continents from Space with Synthetic Aperture Radar (LiCSAR) processing system. Our aim is to evaluate (1) who interacts with disseminated InSAR data, (2) how the data are used and (3) to discuss strategies for meaningful communication and dissemination of open InSAR data. We found that InSAR Twitter activity was primarily associated with natural hazard response, specifically following earthquakes and volcanic activity, where InSAR measurements of ground deformation were disseminated, often using wrapped and unwrapped interferograms. For earthquake events, Sentinel-1 data were acquired, processed, and tweeted within 4.7±2.8 days (shortest was one day). Open access Sentinel-1 data dominated the InSAR tweets and were applied to volcanic and earthquake events in the most engaged with (retweeted) content. Open access InSAR data provided by LiCSAR was widely accessed, including automatically processed and tweeted interferograms and interactive event pages revealing ground deformation following earthquake events. The further work required to integrate dissemination of InSAR data into longer-term disaster risk reduction strategies is highly specific, both to hazard-type, international community of practice, and local political setting and civil protection mandates. Notably, communication of uncertainties and processing methodologies are still lacking. We conclude by outlining the future direction of COMET LiCSAR products to maximise their useability.

Ice shelves play a crucial role in controlling rates of ice discharge across Antarctica’s grounding lines. Mass loss from ice shelves, predominately due to basal melting and calving, can reduce the buttressing force provided by ice shelves, leading to increased grounded ice discharge. Despite the importance of ice shelves, existing estimates of calving and freshwater fluxes from ice shelves have utilised disparate datasets valid for inconsistent time periods or have relied on simplifying assumptions, resulting in a limited account of the health of many ice shelves and little indication of processes driving ice shelf mass imbalance.Here, we quantify calving and basal melt fluxes at annual temporal resolution during 2010 to 2019. Our annual measurements account for annual variations in ice velocity and basal melt rate for 183 ice shelves, and annual variations calving front position for 34 major ice shelves (accounting for ~90% of the ice shelf area). On average during the study period, a calving flux of 1283±109 Gt yr-1 is roughly equal to a melt flux of 1247±149 Gt yr-1. Inter-annual variations in the fluxes of both basal meltwater and calving mean that the melt contribution to ice shelf mass loss varies between 35% and 62%, with the lowest contributions in years with large calving events. These large (>100 Gt) calving events are rare (8 events during 2010-2019), yet account for 35% of the total ice shelf calving flux, highlighting the importance of large calving events for ice shelf mass balance over short time scales. Eighty percent of ice shelves, including many in East Antarctica, are melting at or faster than their balance rates, indicating that ocean-driven erosion of ice shelf grounding lines is widespread around Antarctica. Furthermore, we find a significant and strong positive correlation (R=0.68) between basal melt flux and grounding line discharge, implying that ocean-driven melt may pace grounded ice loss from Antarctica.

The 2019/2020 Australian wildfires emitted large quantities of atmospheric pollutant gases and aerosols. Using state-of-the-art near-real-time satellite measurements of tropospheric composition, we present an analysis of several emitted trace gases and their long-range transport, and compare to the previous (2018/2019) fire season. Observations of carbon monoxide (CO) show that fire emissions were so intense that the distinct Australian fire plume managed to circumnavigate the Southern Hemisphere (SH) within a few weeks, with eastward propagation over the South Pacific, South America, the South Atlantic, Africa, and the Indian Ocean. Elevated atmospheric methane levels were also detected in January 2020 fire plumes over the Pacific, defined using CO as a plume tracer, even though sampling was restricted spatially by aerosols and clouds. Observations also show significant enhancements of methanol (CH3OH) from the fires, where CH3OH:CO enhancement ratios increased within the aged plume downwind over the South Pacific indicating secondary in-plume CH3OH formation.

Funder: U.K. China Research and Innovation Partnership Fund, Funder: National Centre for Atmospheric Science (NCAS); Id: http://dx.doi.org/10.13039/501100000662, Reconstructions of volcanic aerosol radiative forcing are required to understand past climate variability. Currently, reconstructions of pre‐20th century volcanic forcing are derived from sulfate concentrations measured in polar ice cores, mainly using a relationship between the average ice‐sheet sulfate deposition and stratospheric sulfate aerosol burden based on a single explosive eruption—the 1991 eruption of Mt. Pinatubo. Here we estimate volcanic radiative forcings and associated uncertainty ranges from ice‐core sulfate records of eight of the largest bipolar deposition signals in the last 2,500 years using statistical emulation of a perturbed parameter ensemble of aerosol‐climate model simulations of explosive eruptions. Extensive sampling of different combinations of eruption source parameters using the emulators reveals that a very wide range of eruptions in different seasons with different sulfur dioxide emissions, eruption latitudes, and emission altitudes produce ice‐sheet sulfate deposition consistent with ice‐core records. Consequently, we find a large range in the volcanic forcing that can be directly attributed to the unknown eruption source parameters. We estimate that the uncertainty in volcanic forcing caused by many plausible eruption realizations leads to uncertainties in the global mean surface cooling of around 1°C for the largest unidentified historical eruptions. Our emulators are available online (https://cemac.github.io/volcanic-forcing-deposition) where eruption realizations for given ice‐sheet sulfate depositions can be explored.

The Australian 2019/2020 bushfires were unprecedented in their extent and intensity, causing a catastrophic loss of habitat, human and animal life across eastern‐Australia. We use a regional air quality model to assess the impact of the bushfires on particulate matter with a diameter less than 2.5 μm (PM2.5) concentrations and the associated health impact from short‐term population exposure to bushfire PM2.5. The mean population Air Quality Index (AQI) exposure between September and February in the fires and no fires simulations indicates an additional ∼437,000 people were exposed to “Poor” or worse AQI levels due to the fires. The AQ impact was concentrated in the cities of Sydney, Newcastle‐Maitland, Canberra‐Queanbeyan and Melbourne. Between October and February 171 (95% CI: 66–291) deaths were brought forward due to short‐term exposure to bushfire PM2.5. The health burden was largest in New South Wales (NSW) (109 (95% CI: 41–176) deaths brought forward), Queensland (15 (95% CI: 5–24)), and Victoria (35 (95% CI: 13–56)). This represents 38%, 13% and 30% of the total deaths brought forward by short‐term exposure to all PM2.5. At a city‐level 65 (95% CI: 24–105), 23 (95% CI: 9–38) and 9 (95% CI: 4–14) deaths were brought forward from short‐term exposure to bushfire PM2.5, accounting for 36%, 20%, and 64% of the total deaths brought forward from all PM2.5. Thus, the bushfires caused substantial AQ and health impacts across eastern‐Australia. Climate change is projected to increase bushfire risk, therefore future fire management policies should consider this., Key Points The fires led to widespread exposure to “Poor” or worse Air Quality Index levels across eastern‐AustraliaThe highest all‐cause, all‐age mortality from short‐term exposure to bushfire particulate matter with a diameter less than 2.5 μm (PM2.5) was seen in the states of New South Wales, Queensland, and VictoriaAll‐cause, all‐age mortality from short‐term exposure to bushfire PM2.5 was highest in the cities of Sydney, Melbourne, and Canberra

The Antarctic Ice sheet is a key component of the Earth system, impacting on global sea level, ocean circulation and atmospheric processes. Meltwater is generated at the ice sheet base primarily by geothermal heating and friction associated with ice flow, and this feeds a vast network of lakes and rivers creating a unique hydrological environment. Subglacial lakes play a fundamental role in the Antarctic ice sheet hydrological system because outbursts from ‘active’ lakes can trigger, (i) change in ice speed, (ii) a burst of freshwater input into the ocean which generates buoyant meltwater plumes, and (iii) evolution of glacial landforms and sub-glacial habitats. Despite the key role that sub-glacial hydrology plays on the ice sheet environment, there are limited observations of repeat sub-glacial lake activity resulting in poor knowledge of the timing and frequency of these events. Even rarer are examples of interconnected lake activity, where the draining of one lake triggers filling of another. Observations of this nature help us better characterise these events and the impact they may have on Antarctica’s hydrological budget, and will advance our knowledge of the physical mechanism responsible for triggering this activity. In this study we analyse 9-years of CryoSat-2 radar altimetry data, to investigate a newly identified sub-glacial network in the Amery basin, East Antarctica. CryoSat-2 data was processed in ‘swath mode’, increasing the density of elevation measurements across the study area. The plane fit method was employed in 500 m by 500 m grid cells, to measure surface elevation change at relatively high spatial resolution. We identified a network of 10 active subglacial lakes in the Amery basin. 7 of these lakes, located below Lambert Glacier, show interconnected hydrological behaviour, with filling and drainage events throughout the study period. We observed ice surface height change of up to 6 meters on multiple lakes, and these observations were validated by independently acquired TanDEM-X DEM differencing. This case study is an important decade long record of hydrological activity beneath the Antarctic Ice Sheet which demonstrates the importance of high resolution swath mode measurements. In the future the Lambert lake network will be used to better understand the filling and draining life cycle of sub-glacial hydrological activity under the Antarctic Ice Sheet.

The June 2018 Saddleworth Moor fires were some of the largest UK wildfires on record and lasted for approximately three weeks. They emitted large quantities of smoke, trace gases and aerosols which were transported downwind over the highly populated regions of Manchester and Liverpool. Surface observations of PM2.5 indicate that concentrations were 4–5.5 times higher than the recent seasonal average. State-of-the-art satellite measurements of total column carbon monoxide (TCCO) from the TROPOMI instrument on the Sentinel 5—Precursor (S5P) platform, coupled with measurements from a flight of the UK BAe-146–301 research aircraft, are used to quantify the substantial enhancement in emitted trace gases. The aircraft measured plume enhancements with near-fire CO and PM2.5 concentrations >1500 ppbv and >125 μg m−3 (compared to ∼100 ppbv and ∼5 μg m−3 background concentrations). Downwind fire-plume ozone (O3) values were larger than the near-fire location, indicating O3 production with distance from source. The near-fire O3:CO ratio was (ΔO3/ΔCO) 0.001 ppbv/ppbv, increasing downwind to 0.060–0.105 ppbv/ppbv, suggestive of O3 production enhancement downwind of the fires. Emission rates of CO and CO2 ranged between 1.07 (0.07–4.69) kg s−1 and 13.7 (1.73–50.1) kg s−1, respectively, similar to values expected from a medium sized power station.

The article presents a complete analysis of the various international security policies that are being adopted by China, with respect to the two middle-powers, namely Australia and South Korea. The various policies that are adopted by these countries towards China are also analyzed.

The intracellular amino and carboxy termini of P2X receptors have been shown to contribute to the regulation of ATP evoked currents. In this study we produced, and expressed in Xenopus oocytes, individual alanine point mutants of positively charged amino acids (eight lysine, seven arginine and one histidine) in the intracellular domains of the human P2X1 receptor. The majority of these mutations had no effect on the amplitude, time-course or rectification of ATP evoked currents. In contrast the mutant K367A was expressed at normal levels at the cell surface however ATP evoked currents were reduced by >99% and desensitised more rapidly demonstrating a role of K367 in channel regulation. This is similar to that previously described for T18A mutant channels. Co-expression of T18A and K367A mutant P2X1 receptors produced larger ATP evoked responses than either mutant alone and suggests that these amino and carboxy terminal regions interact to regulate channel function.

Bacillus megaterium flavocytochrome P450 BM3 (BM3) is a high activity fatty acid hydroxylase, formed by the fusion of soluble cytochrome P450 and cytochrome P450 reductase modules. Short chain (C6, C8) alkynes were shown to be substrates for BM3, with productive outcomes (i.e. alkyne hydroxylation) dependent on position of the carbon-carbon triple bond in the molecule. Wild-type P450 BM3 catalyses ω-3 hydroxylation of both 1-hexyne and 1-octyne, but is suicidally inactivated in NADPH-dependent turnover with non-terminal alkynes. A F87G mutant of P450 BM3 also undergoes turnover-dependent heme destruction with the terminal alkynes, pointing to a key role for Phe87 in controlling regioselectivity of alkyne oxidation. The terminal alkynes access the BM3 heme active site led by the acetylene functional group, since hydroxylated products are not observed near the opposite end of the molecules. For both 1-hexyne and 1-octyne, the predominant enantiomeric product formed (up to ∼90%) is the (S)-(-)-1-alkyn-3-ol form. Wild-type P450 BM3 is shown to be an effective oxidase catalyst of terminal alkynes, with strict regioselectivity of oxidation and potential biotechnological applications. The absence of measurable octanoic or hexanoic acid products from oxidation of the relevant 1-alkynes is also consistent with previous studies suggesting that removal of the phenyl group in the F87G mutant does not lead to significant levels of ω-oxidation of alkyl chain substrates.

Balancing cost and performance in packaging is critical. This article outlines techniques to assist in this whilst delivering added value and product differentiation. The techniques include a rigorous statistical process capable of delivering cost reduction and improved quality and a computer modelling process that can save time when validating new packaging options.

After working in southern Africa for two months I still feel overwhelmed by the daily emotional and medical demands generated by the AIDS epidemic. I do not know whether my experience reflects that of other doctors, but perhaps an anecdotal report will convey the personal and professional impact of a disease better than a statistical presentation. Considerations of HIV affect almost every decision of my working day—the male and female wards are continually filled with young, wasted adults with persistent coughs and other manifestations of tuberculosis, generalised lymphadenopathy, Kaposi's sarcoma, pyogenic infection, and neural and ocular manifestations of HIV infection. The main reason for admission is to exclude or identify treatable infections, especially pulmonary tuberculosis. The pressure on beds demands early discharge for terminal and untreatable cases despite a hopelessly overstretched home support network. The horror at the magnitude of the problem is compounded by the inadequacy you feel when confronted by another patient deteriorating with a swinging temperature without the resources to investigate or treat the opportunistic infections associated with HIV. Every extra month of health salvaged from this disease is a success for the family and community as these are all parents and bread winners in a society where a hospital stay at planting or harvest time guarantees a malnourished family later in the year. Those deaths that do occur in hospital are most commonly caused by uncontrolled tuberculosis or …