Justice & Paix

Principal composant des déchets marins, le plastique, charrié par les fleuves le plus souvent, arrive par millions de tonnes depuis des décennies dans l'océan. Histoire d'une submersion annoncée. - Une production exponentielle

La surface de glace maximale, enregistrée le 17 septembre, est la plus faible recensée depuis quarante-sept ans, derrière celle de 2024 et celle record de 2023.

Several, more recent global warming projections in the coupled model intercomparison project 6 contain extensions beyond year 2100–2300/2500. The Atlantic meridional overturning circulation (AMOC) in these projections shows transitions to extremely weak overturning below the surface mixed layer (<6 Sv; 1 Sv = 106 m3 s−1) in all models forced by a high-emission (SSP585) scenario and sometimes also forced by an intermediate- (SSP245) and low-emission (SSP126) scenario. These extremely weak overturning states are characterised by a shallow maximum overturning at depths less than 200 m and a shutdown of the circulation associated with North Atlantic deep water formation. Northward Atlantic heat transport at 26°N decreases to 20%–40% of the current observed value. Heat release to the atmosphere north of 45°N weakens to less than 20% of its present-day value and in some models completely vanishes, leading to strong cooling in the subpolar North Atlantic and Northwest Europe. In all cases, these transitions to a

The Atlantic meridional overturning circulation (AMOC) is an important tipping element in the climate system. There is a large uncertainty whether the AMOC will start to collapse during the century under future climate change, as this requires long climate model simulations which are not always available. Here, we analyze targeted climate model simulations done with the Community Earth System Model (CESM) with the aim to develop a physics-based indicator for the onset of an AMOC tipping event. This indicator is diagnosed from the surface buoyancy fluxes over the North Atlantic Ocean and is performing successfully under quasi-equilibrium freshwater forcing, freshwater pulse forcing, climate change scenarios, and for different climate models. An analysis consisting of 25 different climate models shows that the AMOC could begin to collapse by 2063 (from 2026 to 2095, to percentiles) under an intermediate emission scenario (SSP2-4.5), or by 2055 (from 2023 to 2076, to percentiles) under a high-end emission scenar

2024 was the hottest year on record [1], with global temperatures exceeding 1.5 °C above preindustrial climate conditions for the first time and records broken across large parts of Earth’s surface. Among the widespread impacts of exceptional heat, rising food prices are beginning to play a prominent role in public perception, now the second most frequently cited impact of climate change experienced globally, following only extreme heat itself [2]. Recent econometric analysis confirms that abnormally high temperatures directly cause higher food prices, as impacts on agricultural production [3] translate into supply shortages and food price inflation [4, 5]. These analyses track changes in overall price aggregates which are typically slow-moving, but specific food goods can also experience much stronger short-term price spikes in response to extreme heat.

For decades, the surface of the polar Southern Ocean (south of 50°S) has been freshening—an expected response to a warming climate. This freshening enhanced upper-ocean stratification, reducing the upward transport of subsurface heat and possibly contributing to sea ice expansion. It also limited the formation of open-ocean polynyas. Using satellite observations, we reveal a marked increase in surface salinity across the circumpolar Southern Ocean since 2015. This shift has weakened upper-ocean stratification, coinciding with a dramatic decline in Antarctic sea ice coverage. Additionally, rising salinity facilitated the reemergence of the Maud Rise polynya in the Weddell Sea, a phenomenon last observed in the mid-1970s.

Dernièrement, une infographie listait les pays dont les surfaces de forêt tropicale ont le plus diminué en 2024. Si les pays les plus impactés se trouvent en Amazonie, d’autres également touchés se situent ailleurs dans le monde.

Identifying the socio-economic drivers behind greenhouse gas emissions is crucial to design mitigation policies. Existing studies predominantly analyze short-term CO2 emissions from fossil fuels, neglecting long-term trends and other GHGs. We examine the drivers of all greenhouse gas emissions between 1820–2050 globally and regionally. The Industrial Revolution triggered sustained emission growth worldwide—initially through fossil fuel use in industrialized economies but also as a result of agricultural expansion and deforestation. Globally, technological innovation and energy mix changes prevented 31 (17–42) Gt CO2e emissions over two centuries. Yet these gains were dwarfed by 81 (64–97) Gt CO2e resulting from economic expansion, with regional drivers diverging sharply: population growth dominated in Latin America and Sub-Saharan Africa, while rising affluence was the main driver of emissions elsewhere. Meeting climate targets now requires the carbon intensity of GDP to decline 3 times faster than the global

In a rapidly changing climate, evidence-based decision-making benefits from up-to-date and timely information. Here we compile monitoring datasets (published at https://doi.org/10.5281/zenodo.15639576; Smith et al., 2025a) to produce updated estimates for key indicators of the state of the climate system: net emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, the Earth's energy imbalance, surface temperature changes, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes. This year, we additionally include indicators for sea-level rise and land precipitation change. We follow methods as closely as possible to those used in the IPCC Sixth Assessment Report (AR6) Working Group One report.

En raison de la sécheresse, des feux de végétation se sont déclarés dans plusieurs régions depuis le début du printemps. Le pays prend conscience de sa vulnérabilité face aux effets du dérèglement climatique.

We investigate the probabilities of triggering climate tipping points under five Shared Socioeconomic Pathways (SSPs) and how they are altered by including the additional carbon emissions that could arise from tipping points within the Earth's carbon cycle. The crossing of a climate tipping point at a threshold level of global mean surface temperature (threshold temperature) would commit the affected subsystem of the Earth to abrupt and largely irreversible changes with negative impacts on human well-being. However, it remains unclear which tipping points would be triggered under the different SSPs due to uncertainties in the climate sensitivity to anthropogenic greenhouse gas emissions, the threshold temperatures and timescales of climate tipping points, and the response of tipping points within the Earth's carbon cycle to global warming. We include those uncertainties in our analysis to derive probabilities of triggering for 16 previously identified climate tipping points within the Earth system.

Robert F. Kennedy Jr. (RFK Jr.), actuellement à la tête du Département américain de la Santé et des Services sociaux, a tenu des propos pour le moins controversés sur l’autisme lors d’une récente conférence de presse. Selon lui, la hausse des diagnostics serait principalement imputable à des facteurs environnementaux potentiellement nocifs apparus au cours des dernières décennies – une thèse que réfutent fermement les spécialistes. Le responsable politique entend néanmoins lancer une enquête sur les origines du trouble, en faisant abstraction des données scientifiques déjà disponibles.

Près de 55 % de la superficie de l'île d'Amsterdam, dans les Terres australes et antarctiques françaises (TAAF), ont été consumées par l'incendie qui la ravage depuis janvier. La mission d'expertise réalisée fin février n'a pour l'instant pas permis de déterminer les causes de l'incendie.

Le 7 février, « un plus bas record a été atteint concernant la surface de banquise cumulée » autour de l’Arctique et l’Antarctique, indique le bulletin mensuel publié par l’observatoire européen.

The ocean ecosystem is a vital component of the global carbon cycle, storing enough carbon to keep atmospheric CO2 considerably lower than it would otherwise be. However, this conception is based on simple models, neglecting the coupled land-ocean feedback. Using an interactive Earth system model, we show that the role ocean biology plays in controlling atmospheric CO2 is more complex than previously thought. Atmospheric CO2 in a new equilibrium state after the biological pump is shut down increases by more than 50% (163 ppm), lower than expected as approximately half the carbon lost from the ocean is adsorbed by the land. The abiotic ocean is less capable of taking up anthropogenic carbon due to the warmer climate, an absent biological surface pCO2 deficit and a higher Revelle factor. Prioritizing research on and preserving marine ecosystem functioning would be crucial to mitigate climate change and the risks associated with it.

The Antarctic Circumpolar Current (ACC) is the world's strongest ocean current and plays a disproportionate role in the climate system due to its role as a conduit for major ocean basins. This current system is linked to the ocean's vertical overturning circulation, and is thus pivotal to the uptake of heat and CO2 in the ocean. The strength of the ACC has varied substantially across warm and cold climates in Earth's past, but the exact dynamical drivers of this change remain elusive. This is in part because ocean models have historically been unable to adequately resolve the small-scale processes that control current strength. Here, we assess a global ocean model simulation which resolves such processes to diagnose the impact of changing thermal, haline and wind conditions on the strength of the ACC. Our results show that, by 2050, the strength of the ACC declines by ∼20% for a high-emissions scenario. This decline is driven by meltwater from ice shelves around Antarctica, which is exported to lower latit

January 2025 was the 18th month in a 19-month period with a global-average surface air temperature exceeding 1.5ºC above pre-industrial levels. According to the Copernicus Climate Change Service…

La Wallonie soutient-elle suffisamment l’agriculture bio ? En regard du plan visant 30% de surfaces agricoles en bio d’ici 2030, la question se pose. Actuellement, ce sont 7,6% des terres belges qui sont exploitées en bio. Mais malgré les primes, les agriculteurs bio rencontrent des obstacles financiers. De plus, le développement des circuits courts et des filières locales détourne parfois l’attention du bio.

L'Agence européenne de l'environnement lance mardi un appel à mieux gérer les ressources en eau sur le continent, alors que seulement 37 % des eaux de surface sont en bonne santé écologique. Elle recommande une réduction drastique du recours aux pesticides d'ici 2030 et un virage vers "des pratiques naturelles et agroécologiques plus durables".

Avec seulement 37 % de ses eaux de surface en bonne ou très bonne santé écologique, l’Europe doit mieux gérer ses ressources pour garantir à ses citoyens de l’eau de bonne qualité, a prévenu ce mardi 15 octobre un important rapport.

Understanding how global mean surface temperature (GMST) has varied over the past half-billion years, a time in which evolutionary patterns of flora and fauna have had such an important influence on the evolution of climate, is essential for understanding the processes driving climate over that interval. Judd et al. present a record of GMST over the past 485 million years that they constructed by combining proxy data with climate modeling (see the Perspective by Mills). They found that GMST varied over a range from 11° to 36°C, with an “apparent” climate sensitivity of ∼8°C, about two to three times what it is today. —Jesse Smith

On peut encore éviter une 6e extinction de masse. Une étude menée par des scientifiques a révélé qu’en protégeant “seulement” 1,2% de la surface de la planète, nous pourrions éviter la disparation de très nombreuses espèces. Novethic vous propose désormais chaque semaine un “pas de côté” sur l’actu.

Subsurface Temperature Profiles

En un an, la baisse est chiffrée par l’Agence Bio à 54 000 hectares. Parallèlement, le mouvement de déconversion des agriculteurs s’est poursuivi. Et la tendance pourrait se détériorer encore en 2024.

Fruit de la collaboration d’une centaine d’auteurs de 28 pays, le rapport de la Commission océanographique intergouvernementale publié lundi 3 juin dresse un état des lieux inquiétant du monde océanique.

Elizabeth Kolbert on a record-breaking rise in global sea-surface temperatures, which suggests that scientists may not understand how fast the climate is changing.

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

Avant de revenir ces derniers jours, la neige avait disparu d'une grande partie des massifs alpins et pyrénéens pendant la quasi-totalité du mois de février. Du jamais-vu ces dernières décennies, à une telle période.

La banquise de l'Antarctique a atteint sa surface maximale pour l'année, soit 16,96 millions de km². Mais celle-ci n'a jamais été aussi petite depuis le début des relevés scientifiques en 1979, a annoncé lundi l'observatoire américain de référence.

L’étendue maximale atteinte cette année est de 1,03 million de kilomètres carrés inférieure à la plus faible précédemment enregistrée, soit près de deux fois la superficie de la France.

Daily Sea Surface Temperature

Bonn and Geneva, 6 September 2023 (ECMWF and WMO) - Earth just had its hottest three months on record, according to the European Union-funded Copernicus Climate Change Service (C3S) implemented by ECMWF. Global sea surface temperatures are at unprecedented highs for the third consecutive month and Antarctic sea ice extent remains at a record low for the time of year.

l’Espagne risquerait de voir les trois quarts de son territoire transformés en désert. Des études conduites par des ONG et le gouvernement sur le sujet mènent bien à ce type d’alerte d’ici à la fin du siècle.

In March and April 2023, some Earth scientists began to point out that average sea surface temperatures had surpassed the highest levels seen in a key data record maintained by NOAA. Months later, they remain at record levels, with global sea surface temperatures 0.99°C (1.78°F) above average in July. That was the fourth consecutive month they were at record levels.

Les forêts du nord de l’Europe ont moins brûlé qu’en 2022, mais dans certains pays les surfaces incendiées sont très au-dessus de la moyenne.

Chaque semaine, “Courrier international” explique ses choix éditoriaux. Dans ce numéro, nous avons choisi de vous parler d’une poussée de fièvre, celle qui touche les eaux de surface de la Méditerranée et de l’Atlantique Nord, notamment. D’où vient cette montée en température des océans ? Quelles conséquences a-t-elle sur le climat et sur la vie aquatique ? La presse étrangère tente de trouver les réponses.

Selon un rapport publié ce lundi 21 août, la sécheresse des sols concernait 28 % du territoire européen début août, contre 55,8 % l’année dernière. Mais le niveau des nappes phréatiques reste très bas.

Une étude parue dans la revue « Science Advances » confirme la tendance globale à la perte d’humidité en lien avec le réchauffement du climat, avec de multiples conséquences délétères.

Le Covid ne prend toujours pas de vacances et refait parler de lui au coeur de l'été en France comme dans d'autres pays, avec un rebond épidémique jusqu'alors modéré mais invitant à la vigilance.

Ces données concernent les océans entre les 60e parallèles nord et sud, excluant donc uniquement les régions polaires.