Brief communication: A submarine wall protecting the Amundsen Sea intensifies melting of neighboring ice shelves

Disintegration of ice shelves in the Amundsen Sea, in front of the West Antarctic Ice Sheet, has the potential to cause sea level rise by inducing an acceleration of ice discharge from upstream grounded ice. Moore et al. (2018) proposed that using a submarine wall to block the penetration of warm water into the subsurface cavities of these ice shelves could reduce this risk. We use a global sea ice–ocean model to show that a wall shielding the Amundsen Sea below 350 m depth successfully suppresses the inflow of warm water and reduces ice shelf melting. However, these warm water masses get redirected towards neighboring ice shelves, which reduces the net effectiveness of the wall. The ice loss is reduced by 10 %, integrated over the entire Antarctic continent

Reaching the 1.5 degree limit: what does it mean for West Antarctica and the global mean sea level?

What are the benefits of limiting the global warming to 1.5 degree with respect to pre-industrial conditions for the vulnerable region of West Antarctica which might be prone to positive feedback mechanisms between ocean circulation, melting of shelf ice and instabilities of the ice sheet? There are indications that West Antarctic ice sheet instabilities have occurred in the Last Interglacial around 125.000 years ago. At that time the polar surface temperature was about 2K warmer than today. The question under which circumstances a tipping point may be reached and if this may happen again is therefore highly relevant, especially since a disintegration of the West Antarctic ice sheet could cause a global sea level rise between 3 and 5 m. Here we address this question with variable resolution, global coupled ice sheet - shelf ice - ocean - atmosphere multi-century simulations. With our innovative ocean modelling approach in the Finite Element Sea-ice Ocean Model FESOM it is possible to refine the ocean resolution to up to 3 km in the Amundsen Sea and 10 km around the whole Antarctica while keeping it relatively coarse in the order of a couple of hundred km in dynamically not very active regions such as the subtropical regions. This means that we can simulate the feedback between ocean and ice in the relevant regions highly resolved given that the ice sheet model runs at a resolution of 5 to 10 km. Three different emission scenarios are applied up to 2100, two of them limiting the global mean temperature increase to 1.5 ◦ C and 2 ◦ C respectively and one of them assuming business-as-usual conditions (IPCC SRES RCP8.5 scenario). The simulations are extended to 2400 with the greenhouse gas and aerosol concentrations kept constant at 2100 levels, respectively, to be able to simulate the long-term implications of different global warming levels

Global carbon budget 2022

Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodologies to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly, and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) is estimated with global ocean biogeochemistry models and observation-based data products. The terrestrial CO2 sink (SLAND) is estimated with dynamic global vegetation models. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the year 2021, EFOS increased by 5.1% relative to 2020, with fossil emissions at 10.1±0.5GtCyr-1 (9.9±0.5GtCyr-1 when the cement carbonation sink is included), and ELUC was 1.1±0.7GtCyr-1, for a total anthropogenic CO2 emission (including the cement carbonation sink) of 10.9±0.8GtCyr-1 (40.0±2.9GtCO2). Also, for 2021, GATM was 5.2±0.2GtCyr-1 (2.5±0.1ppmyr-1), SOCEAN was 2.9 ±0.4GtCyr-1, and SLAND was 3.5±0.9GtCyr-1, with a BIM of -0.6GtCyr-1 (i.e. the total estimated sources were too low or sinks were too high). The global atmospheric CO2 concentration averaged over 2021 reached 414.71±0.1ppm. Preliminary data for 2022 suggest an increase in EFOS relative to 2021 of +1.0% (0.1% to 1.9%) globally and atmospheric CO2 concentration reaching 417.2ppm, more than 50% above pre-industrial levels (around 278ppm). Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959-2021, but discrepancies of up to 1GtCyr-1 persist for the representation of annual to semi-decadal variability in CO2 fluxes. Comparison of estimates from multiple approaches and observations shows (1) a persistent large uncertainty in the estimate of land-use change emissions, (2) a low agreement between the different methods on the magnitude of the land CO2 flux in the northern extratropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set. The data presented in this work are available at 10.18160/GCP-2022 (Friedlingstein et al., 2022b)

Abruptly attenuated carbon sequestration with Weddell Sea dense waters towards the end of the 21st century

Antarctic Bottom Water formation, such as in the Weddell Sea, is an efficient vector for carbon sequestration on time scales of centuries. Yet, possible changes in carbon sequestration under changing environmental conditions are unquantified to date, mainly due to difficulties in simulating the relevant processes on high-latitude continental shelves. Using a model setup including both ice-shelf cavities and oceanic carbon cycling, we demonstrate that by 2100, deep-ocean carbon accumulation in the southern Weddell Sea is abruptly attenuated to only 40% of the rate in the 1990s in a high-emission scenario, while still being 4-fold higher in the 2080s. By assessing deep-ocean carbon budgets and water mass transformations, we show that this decline can be attributed to an increased presence of Warm Deep Water on the southern Weddell Sea continental shelf, a 16% reduction in sea-ice formation, and a 79% increase in ice-shelf basal melt. Altogether, these changes lower the density and volume of newly formed bottom waters and reduce the associated carbon transport to the abyss

Evaluation of air-sea CO2 fluxes in the ocean-ecosystem model FESOM-REcoM and in the Global Carbon Budget Models

We assessed air-sea CO2 fluxes in the ocean circulation ecosystem model FESOM-REcoM. FESOM is a finite element sea ice-ocean model, with a variable resolution ocean mesh. The mesh used here has a nominal resolution of 150 km in the open ocean and reaches 25 km in the tropics and in the Arctic region. While FESOM-REcoM has previously been used to study biogeochemical cycles and physics-ecosystem interactions, we have now evaluated the air-sea CO2 exchange in a preindustrial control simulation and in a historical simulation with varying climate and increasing atmospheric CO2 concentrations. We evaluate the total annual CO2 uptake and its regional distribution of the historical run and compare modelled pCO2 to observed pCO2 from the SOCAT data-base. The relative interannual variability mismatch and RMSE are similar to that calculated with the same biogeochemical model coupled to the MITgcm ocean circulation model. These numbers and further metrics for model evaluation e.g. natural CO2 fluxes, mismatch time-series, seasonal cycle are set into context by providing the same evaluation for the Global Carbon Budget (GCB) Models. This closes a gap, as these estimates of the ocean carbon sink are used in the community, but their performance has not been documented in detail. We’ll further present methodological updates to the ocean carbon sink estimate in the latest GCB release

Successful Treatment of Uterine Arteriovenous Malformation due to Uterine Trauma

Uterine arteriovenous malformation (AVM) is defined as abnormal and nonfunctional connections between the uterine arteries and veins. Although the patients typically present with vaginal bleeding, some patients may experience life-threatening massive bleeding in some circumstances. The treatment of choice depends on the symptoms, age, desire for future fertility, and localization and size of the lesion; however, embolization of the uterine artery is the first choice in symptomatic AVM in patients at reproductive age with expectations of future fertility. We report a case of acquired AVM (after D/C) with an extensive lesion, which was successfully treated with bilateral uterine artery embolization (UAE)

Prognostic stratification of patients with T3N1M0 non-small cell lung cancer: which phase should it be?

In the 1997 revision of the TNM staging system for lung cancer, patients with T3N0M0 disease were moved from stage IIIA to stage IIB since these patients have a better prognosis. Despite this modification, the local lymph node metastasis remained the most important prognostic factor in patients with lung cancer. The present study aimed to evaluate the prognosis of patients with T3N1 disease as compared with that of patients with stages IIIA and IIB disease. During 7-year period, 313 patients with non-small cell lung cancer (297 men, 16 women) who had resection were enrolled. The patients were staged according the 2007 revision of Lung Cancer Staging by American Joint Committee on Cancer. The Kaplan-Meier statistics was used for survival analysis, and comparisons were made using Cox proportional hazard method. The 5-year survival of patients with stage IIIA disease excluding T3N1 patients was 40%, whereas the survival of the patients with stage IIB disease was 66% at 5 years. The 5-year survival rates of stage III T3N1 patients (single-station N1) was found to be higher than those of patients with stage IIIA disease (excluding pT3N1 patients, P = 0.04), while those were found to be similar with those of patients with stage IIB disease (P = 0.4). Survival of the present cohort of patients with T3N1M0 disease represented the survival of IIB disease rather than IIIA non-small cell lung cancer. Further studies are needed to suggest further revisions in the recent staging system regarding T3N1MO disease

High-resolution modelling of marine biogenic aerosol precursors in the Arctic realm

The presence of liquid or ice as cloud phase determines the climate radiative effect of Arctic clouds, and thus, their contribution to surface warming. Biogenic aerosols from phytoplankton production localized in leads or open water were shown to act as cloud condensation nuclei (liquid phase) or ice nuclei (ice phase) in remote regions. As extensive measurements of biogenic aerosol precursors are still scarce, we conduct a modelling study and use acidic polysaccharides (PCHO) and transparent exopolymer particles (TEP) as tracers. In this study, we integrate processes of algal PCHO excretion during phytoplankton growth or under nutrient limitation and processes of TEP formation, aggregation and also remineralization into the ecosystem model REcoM2. The biogeochemical processes are described by two functional phytoplankton and two zooplankton classes, along with sinking detritus and several (in)organic carbon and nutrient classes. REcoM2 is coupled to the finite-volume sea ice ocean circulation model FESOM2 with a high resolution of up to 4.5 km in the Arctic. We will present the first results of simulated TEP distribution and seasonality patterns at pan-Arctic scale over the last decades. We will elucidate drivers of the seasonal cycle and will identify regional hotspots of TEP production and its decay. We will also address possible impacts of global warming and Arctic amplification of the last decades in our evaluation, as we expect a strong effect of global warming on microbial metabolic rates, phytoplankton growth, and composition of phytoplankton functional types. The results will be evaluated by comparison to a set of in-situ measurements (PASCAL, FRAM, MOSAiC). It is further planned that an atmospheric aerosol-climate model will build on the modeled biogenic aerosol precursors as input to quantify the net aerosol radiative effects. This work is part of the DFG TR 172 Arctic Amplification