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Cadrage et enjeux

Over the past 50 years, humans have extracted the Earth’s groundwater stocks at a steep rate, largely to fuel global agro-economic development. Given society’s growing reliance on groundwater, we explore ‘peak water limits’ to investigate whether, when and where humanity might reach peak groundwater extraction. Using an integrated global model of the coupled human–Earth system, we simulate groundwater withdrawals across 235 water basins under 900 future scenarios of global change over the twenty-first century. Here we find that global non-renewable groundwater withdrawals exhibit a distinct peak-and-decline signature, comparable to historical observations of other depletable resources (for example, minerals), in nearly all (98%) scenarios, peaking on average at 625 km3 yr−1 around mid-century, followed by a decline through 2100. The peak and decline occur in about one-third (82) of basins, including 21 that may have already peaked, exposing about half (44%) of the global population to groundwater stress. Most

Global projections of macroeconomic climate-change damages typically consider impacts from average annual and national temperatures over long time horizons1–6. Here we use recent empirical findings from more than 1,600 regions worldwide over the past 40 years to project sub-national damages from temperature and precipitation, including daily variability and extremes7,8. Using an empirical approach that provides a robust lower bound on the persistence of impacts on economic growth, we find that the world economy is committed to an income reduction of 19% within the next 26 years independent of future emission choices (relative to a baseline without climate impacts, likely range of 11–29% accounting for physical climate and empirical uncertainty). These damages already outweigh the mitigation costs required to limit global warming to 2 °C by sixfold over this near-term time frame and thereafter diverge strongly dependent on emission choices. Committed damages arise predominantly through changes in average tempe

.Contribution to (a) effective radiative forcing (ERF) and (b) global surface temperature change from component emissions for1750–2019based on Coupled Model Intercomparison Project Phase 6 (CMIP6) models and (c) net aerosol ERF for 1750–2014 from different lines of evidence.

Evidence shows a continuing increase in the frequency and severity of global heatwaves1,2, raising concerns about the future impacts of climate change and the associated socioeconomic costs3,4. Here we develop a disaster footprint analytical framework by integrating climate, epidemiological and hybrid input–output and computable general equilibrium global trade models to estimate the midcentury socioeconomic impacts of heat stress. We consider health costs related to heat exposure, the value of heat-induced labour productivity loss and indirect losses due to economic disruptions cascading through supply chains. Here we show that the global annual incremental gross domestic product loss increases exponentially from 0.03 ± 0.01 (SSP 245)–0.05 ± 0.03 (SSP 585) percentage points during 2030–2040 to 0.05 ± 0.01–0.15 ± 0.04 percentage points during 2050–2060. By 2060, the expected global economic losses reach a total of 0.6–4.6% with losses attributed to health loss (37–45%), labour productivity loss (18–37%) and i

Mitigating climate change necessitates global cooperation, yet global data on individuals’ willingness to act remain scarce. In this study, we conducted a representative survey across 125 countries, interviewing nearly 130,000 individuals. Our findings reveal widespread support for climate action. Notably, 69% of the global population expresses a willingness to contribute 1% of their personal income, 86% endorse pro-climate social norms and 89% demand intensified political action. Countries facing heightened vulnerability to climate change show a particularly high willingness to contribute. Despite these encouraging statistics, we document that the world is in a state of pluralistic ignorance, wherein individuals around the globe systematically underestimate the willingness of their fellow citizens to act. This perception gap, combined with individuals showing conditionally cooperative behaviour, poses challenges to further climate action. Therefore, raising awareness about the broad global support for climat

Anthropogenic emissions drive global-scale warming yet the temperature increase relative to pre-industrial levels is uncertain. Using 300 years of ocean mixed-layer temperature records preserved in sclerosponge carbonate skeletons, we demonstrate that industrial-era warming began in the mid-1860s, more than 80 years earlier than instrumental sea surface temperature records. The Sr/Ca palaeothermometer was calibrated against ‘modern’ (post-1963) highly correlated (R2 = 0.91) instrumental records of global sea surface temperatures, with the pre-industrial defined by nearly constant (<±0.1 °C) temperatures from 1700 to the early 1860s. Increasing ocean and land-air temperatures overlap until the late twentieth century, when the land began warming at nearly twice the rate of the surface oceans. Hotter land temperatures, together with the earlier onset of industrial-era warming, indicate that global warming was already 1.7 ± 0.1 °C above pre-industrial levels by 2020. Our result is 0.5 °C higher than IPCC estim

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GIEC rapport - Changements climatique 2021 - rapport technique du 6ème rapport du GIEC du groupe 1 - en français

Ocean-driven melting of floating ice-shelves in the Amundsen Sea is currently the main process controlling Antarctica’s contribution to sea-level rise. Using a regional ocean model, we present a comprehensive suite of future projections of ice-shelf melting in the Amundsen Sea. We find that rapid ocean warming, at approximately triple the historical rate, is likely committed over the twenty-first century, with widespread increases in ice-shelf melting, including in regions crucial for ice-sheet stability. When internal climate variability is considered, there is no significant difference between mid-range emissions scenarios and the most ambitious targets of the Paris Agreement. These results suggest that mitigation of greenhouse gases now has limited power to prevent ocean warming that could lead to the collapse of the West Antarctic Ice Sheet. The authors use a regional ocean model to project ocean-driven ice-shelf melt in the Amundsen Sea. Already committed rapid ocean warming drives increased melt, regard

L’objectif de cet article est d’esquisser les contours d’une sociologie de l’éducation au changement climatique. Pour ce faire, nous discutons du récit paradoxal sur l’urgence climatique, selon lequel nos sociétés ne réagissent pas alors qu’elles entendent l’alerte. Notre hypothèse est que ce récit d’(in)action publique, devenu leitmotiv, cadre de manière inadéquate la manière dont nous pensons l’éducation au changement climatique. En examinant la manière dont l’éducation au changement climatique a été traditionnellement pensée et pratiquée, nous constatons qu’elle est le plus souvent basée sur un modèle inadéquat qui rend les gens réticents à recevoir des informations sur le changement climatique et crée un fossé entre les attitudes et les comportements. Cependant, nous identifions aussi la montée en puissance de nouvelles façons d’envisager l’éducation au changement climatique. Recourant souvent à l’art, celles-ci semblent prometteuses car rendant sensibles et tangibles les transformations en cours elles pe

Les forêts françaises couvrent 31% du territoire métropolitain. Elles contribuent de multiples façons au bienêtre humain (production de bois, purification de l’air et de l’eau, maintien des sols, habitat pour la biodiversité, alimentation, santé, activités récréatives, etc.) et participent aux Objectifs de Développement Durable fixés par l’ONU. En particulier, la France s’étant engagée à atteindre la neutralité carbone dès 2050, le rôle de puits et de stockage de carbone des forêts est considéré comme un élément majeur de sa Stratégie Nationale Bas Carbone (SNBC). Depuis quelques années, les forêts françaises, dont la surface n’avait cessé de croître depuis plus d’un siècle, connaissent, de façon inquiétante, une diminution de productivité, des dépérissements massifs et un risque incendie accru. Le changement climatique en cours met ainsi en péril les ressources forestières et leur contribution attendue pour préserver la biodiversité, favoriser le développement rural et la bioéconomie, renforcer la production

L’Agenda 21 local de la commune de Saint-Gilles (Bruxelles, Belgique) est désormais remplacé par le Plan Climat Saint-gillois (PCSG) qui s’articule autour de trois axes: l’énergie, la mobilité et la nature. Ce Plan est complété par la présente étude qui effectue : 1) la synthèse des perspectives climatiques pour la Belgique et Bruxelles à l’horizon 2050-2100 pour les principaux aléas concernés par le changement climatique ; 2) l’analyse des risques et vulnérabilités du territoire de Saint-Gilles en lien avec le changement climatique et l’identification des inégalités environnementales corollaires.

Un guide sur l’attribution pour les journalistes - traduction

Summary for Policymakers. A Report of the Intergovernmental Panel on Climate Change

WMO's annual State of the Climate in Europe report explores changes in climate indicators, extreme events and climate policy.

Mitigation of Climate Change - Working Group III contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

This paper catalogues current efforts to address climate change within multilateral economic and financial institutions and related organizations. It also proposes a minimum set of policy measures that need to be prioritized by such institutions to support climate change mitigation and adaptation. The proposals include expanding public climate finance via multilateral development banks, doing more to mobilize private investment, mainstreaming climate considerations across institutional operations, making climate disclosures mandatory, and addressing sovereign debt distress to unlock private climate finance.

The IPCC is currently in its Sixth Assessment cycle, during which the IPCC will produce the Assessment reports of its three Working Groups, three Special Reports, a refinement to the methodology report and the Synthesis Report. The Synthesis Report will be the last of the AR6 products, due for release in March 2023.

AR6 Synthesis Report