Progress in paleoclimate modeling

International audienceThis paper briefly surveys areas of paleoclimate modeling notable for recent progress. New ideas, including hypotheses giving a pivotal role to sea ice, have revitalized the low-order models used to simulate the time evolution of glacial cycles through the Pleistocene, a prohibitive length of time for comprehensive general circulation models (GCMs). In a recent breakthrough, however, GCMs have succeeded in simulating the onset of glaciations. This occurs at times (most recently, 115 kyr B.P.) when high northern latitudes are cold enough to maintain a snow cover and tropical latitudes are warm, enhancing the moisture source. More generally, the improvement in models has allowed simulations of key periods such as the Last Glacial Maximum and the mid-Holocene that compare more favorably and in more detail with paleoproxy data. These models now simulate ENSO cycles, and some of them have been shown to reproduce the reduction of ENSO activity observed in the early to middle Holocene. Modeling studies have demonstrated that the reduction is a response to the altered orbital configuration at that time. An urgent challenge for paleoclimate modeling is to explain and to simulate the abrupt changes observed during glacial epochs (i.e., Dansgaard-Oescher cycles, Heinrich events, and the Younger Dryas). Efforts have begun to simulate the last millennium. Over this time the forcing due to orbital variations is less important than the radiance changes due to volcanic eruptions and variations in solar output. Simulations of these natural variations test the models relied on for future climate change projections. They provide better estimates of the internal and naturally forced variability at centennial time scales, elucidating how unusual the recent global temperature trends are

Effets induits des grandes infrastructures : synthèse de l'analyse bibliographique

Ce rapport constitue la synthèse de l'étude bibliographique réalisée dans le cadre de l'action du programme, menée sur trois ans, dont il est la première phase, et qui porte plus largement sur la problématique des effets induits des grandes infrastructures . L'analyse a été volontairement limitée à une cinquantaine de références centrées d'une part, sur les effets socio-économiques, il s'agit d'études réalisées en application de la loi d'orientation sur les transports intérieurs, et d'autre part, sur les infrastructures autoroutières et voies ferrées à grande vitesse. L'objectif de cette approche vise non seulement à dresser un état des lieux de la connaissance et des pratiques d'études sur le thème des effets induits, mais aussi, à repérer les marges de progrès et de renouvellements à la fois dans les concepts et les méthodes. En conséquence, le rapport est conçu selon deux parties : • la première consacrée à l'état des connaissances et des pratiques, notamment sur le concept d'effets induits et sur la mesure de ces effets, • la deuxième développée autour du constat que l'évolution de la représentation spatiale rend nécessaire le renouvellement des concepts et des pratiques

Coherent signature of warming-induced extreme sub-continental boreal wildfire activity 4800 and 1100 years BP

Climate changes are expected to progressively increase extreme wildfire frequency in forests. Finding past analogs for periods of extreme biomass burning would provide valuable insights regarding what the effects of warming might be for tree species distribution, ecosystem integrity, atmospheric greenhouse gas balance, and human safety. Here, we used a network of 42 lake-sediment charcoal records across a ~2000 km transect in eastern boreal North America to infer widespread periods of wildfire activity in association with past climate conditions. The reconstructed fluctuations in biomass burning are broadly consistent with variations in ethane concentration in Greenland polar ice cores. Biomass burning fluctuations also significantly co-varied with Greenland temperatures estimated from ice cores, at least for the past 6000 years. Our retrospective analysis of past fire activity allowed us to identify two fire periods centered around 4800 and 1100 BP, coinciding with large-scale warming in northern latitudes and having respectively affected an estimated ~71% and ~57% of the study area. These two periods co-occurred with widespread decreases in mean fire-return intervals. The two periods are likely the best analogs for what could be anticipated in terms of impacts of fire on ecosystem services provided by these forests in coming decades

En ville, sans ma voiture ! Evaluation du 22 septembre 2000 : résultats et analyses

A partir des enquêtes, des observations et des entretiens réalisés dans une douzaine de villes françaises et plusieurs villes étrangères, les principaux enseignements de la journée sont les suivants :- l'opinion publique locale est toujours très favorable à ce type d'opération (plus de 80 %), à l'exception des commerçants ; ce niveau de satisfaction est élevé dans tous les pays d’Europe, même s’il l’est un peu moins en Allemagne (autour de 70 %).- la fréquentation du centre ville est d’un niveau équivalent à un jour ordinaire, avec quelques disparités dans certaines villes selon les types de commerces ou de services, et les grandes surfaces périphériques n’ont pas plus de clients qu’un jour ordinaire;- l’usage de la bicyclette et de la marche s’accroît ainsi que la fréquentation des transports collectifs ;- en matière d’environnement, la baisse du niveau de bruit et surtout le changement d’ambiance sonore est apprécié par les citadins. On constate une baisse de pollution dans les périmètres réservés. Par contre, cette journée a peu d’influence sur les niveaux de pollution de fond

A predictive classifier of poor prognosis in transplanted patients with juvenile myelomonocytic leukemia: a study on behalf of the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire

Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric myeloproliferative neoplasm requiring hematopoietic stem cell transplantation (HSCT) in most cases. We retrospectively analyzed 119 JMML patients who underwent first allogeneic HSCT between 2002 and 2021. The majority (97%) carried a RAS-pathway mutation, and 62% exhibited karyotypic alterations or additional mutations in SETBP1, ASXL1, JAK3 and/or the RAS pathway. Relapse was the primary cause of death, with a 5-year cumulative incidence of 24.6% (95%CI: 17.1-32.9). Toxic deaths occurred in 12 patients, resulting in treatmentrelated mortality (TRM) of 9.0% (95%CI: 4.6-15.3). The 5-year overall (OS) and event-free survival were 73.6% (95%CI: 65.7-82.4) and 66.4% (95%CI: 58.2-75.8), respectively. Four independent adverse prognostic factors for OS were identified: age at diagnosis >2 years, time from diagnosis to HSCT >6 months, monocyte count at diagnosis >7.2x109/L, and the presence of additional genetic alterations. Based on these factors, we proposed a predictive classifier. Patients with three or more predictors (21% of the cohort) had a 5-year OS of 34.2%, whereas those with none (7%) had a 5-year OS of 100%. Our study demonstrates improved transplant outcomes compared to prior published data, which can be attributed to the synergistic impacts of a low TRM and a reduced yet still substantial relapse incidence. By integrating genetic information with clinical and hematological features, we have devised a predictive classifier. This classifier effectively identifies a subgroup of patients who are at a heightened risk of unfavorable post-transplant outcomes who would benefit novel therapeutic agents and post-transplant strategies

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Amount of CO2 emissions irreversibly leading to the total melting of Greenland

International audience[1] The long-term response of Greenland to anthropogenic warming is of critical interest for the magnitude of the sea-level rise and for climate-related concerns. To explore its evolution over several millennia we use a climate-ice sheet model forced by a range of CO 2 emission scenarios, accounting for the natural removal of anthropogenic CO 2 from the atmosphere. Above 3000 GtC, the melting appears irreversible, while below 2500 GtC, Greenland only experiences a partial melting followed by a re-growth phase. Delaying emissions through sequestration slows significantly the melting, but has only a limited impact on the ultimate fate of Greenland. Its behavior is therefore mostly dependent on the cumulative CO 2 emissions. This study demonstrates that the fossil fuel emissions of the next century will have dramatic consequences on sea-level rise for several millennia. Citation: Charbit, S., D. Paillard, and G. Ramstein (2008), Amount of CO 2 emissions irreversibly leading to the total melting of Greenland, Geophys. Res. Lett., 35, L12503

VIVALDI, A H2020 European Project aiming at preventing and mitigating farmed bivalve diseases

The European shellfish industry enjoys a privileged position on the global scene. Its social dimension is essential, as it employs a high number of people in more than 8000 companies, mostly micro-companies. Shellfish production in Europe is little diversified and mainly relies on the industrially produced mussels, oysters and clams. Over the recent years, this sector has grown more slowly than other fish farming sectors, notably because it depends a great deal on the environmental quality and the emergence of diseases. Mortality events, linked to pathogen organisms such as viruses, bacteria and parasites (protozoa), tend to weaken the production’s sustainability. In this context, the European project VIVALDI (PreVenting and mItigating farmed biVALve DIseases) aims at increasing the sustainability and competitiveness of the shellfish industry in Europe, developing tools and approaches with a view to better preventing and controlling marine bivalve diseases. VIVALDI is a 4-years European Horizon 2020 project coordinated by Ifremer (2016-2020): 21 mostly European, public and private partners are involved, representing the diversity of the European shellfish industry landscap

Synthesis and Packaging of Nanocrystals by Ultra Low Energy Ion Implantation for Applications in Electronics, Optics and Plasmonics

International audienc