Articles 2020

Un phénomène aussi spectaculaire que méconnu a frappé la côte andalouse le 17 août 2025. Les habitants de Motril, Salobreña et Torrenueva Costa (sud de l’Espagne) ont vu le ciel s’assombrir brièvement, avant que des vents violents et un air brûlant ne s’abattent sans prévenir sur la côte. En quelques minutes, les températures ont grimpé à 40,1 °C, des rafales ont soufflé à 87 km/h, et l’humidité a chuté de façon drastique. Au large, certains témoins déclarent avoir vu une sorte de tornade marine, probablement un vortex de chaleur (the watchers).

La France a traversé une vague de chaleur exceptionnelle. Le GIEC et Jean Jouzel préviennent que les canicules s’intensifieront dans les prochaines décennies, et que nous décidons maintenant …

Il y a 250 millions d’années, la Terre a connu la plus grande extinction de masse de son histoire : la crise Permien-Trias (PTME). Environ 90 % des espèces marines et 89 % des tétrapodes terrestres ont disparu. Un volcanisme cataclysmique dans en Sibérie, a provoqué ce changement par le relâchement d’énormes quantités de CO₂, de méthane et d’autres composés toxiques dans l’atmosphère. Ensuite, un super-effet de serre a régné sur la planète pendant près de 5 millions d’années, bien après la fin du volcanisme actif.

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.

Une enquête de l’ONG britannique révèle que plus de neuf activistes sur dix ont été victimes d’attaques sur les réseaux sociaux en lien avec leur engagement en faveur du climat ou de l’environnement.

En juin 2025, la température moyenne mondiale a été de +1,03 °C au-dessus de la moyenne 1951‑1980. Cela fait de juin 2025 le troisième juin le plus chaud jamais enregistré, derrière juin 2024 et juin 2023 .

Malgré le ralentissement des émissions globales de gaz à effet de serre (GES), les voyants du climat restent dans le rouge, nous rappelle le rapport Indicators of Global Climate Change 2024 récemment publié. Ce rapport permet également d’identifier trois leviers d’action à mettre en œuvre pour stabiliser le stock atmosphérique de GES à l’origine du réchauffement global.

The startup Gigablue announced with fanfare this year that it reached a historic milestone: selling 200,000 carbon credits to fund what it describes as a groundbreaking technology in the fight against climate change . But outside scientists frustrated by the lack of information released by the company say serious questions remain about whether Gigablue’s technology works as the company describes. Their questions showcase tensions in an industry built on little regulation and big promises — and a tantalizing chance to profit.

Comment visualiser concrètement l’évolution des températures depuis 1880 ? Comment rendre accessibles les données scientifiques de la NASA ? C’est ce qui m’a motivé à créer NASA GISTEMP Viewer, une application web qui permet de voir les données sur une sphère en 3D.

Between 80% and 89% of the world’s people want their governments to do more about climate change. This fact is the central tenet of the 89% Project for climate journalism. Timed to coincide with Earth Day and Earth Week, the project launched in April, 2025, and will culminate in another week of focused stories in October, just before the next COP meeting in Brazil.

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.

An international group of researchers has produced a third update to key indicators of the state of the climate system set out in the IPCC AR6 assessment, building on previous editions in 2023 and 2024. Forster et al. (2025) assess emissions, concentrations, temperatures, energy transfers, radiation balances, and the role of human activity and conclude that, while natural climate variability also played a role, the record observed temperatures in 2024 were dominated by human activity and the remaining carbon budget for 1.5° C is smaller than ever.

The human fingerprint on global warming was likely evident in Earth’s atmosphere far earlier than previously thought—even before the invention of modern cars, a new study says. Using a combination of scientific theory, modern observations and multiple, sophisticated computer models, researchers found a clear signal of human-caused climate change was likely discernible with high confidence as early as 1885, just before the advent of gas-powered cars but after the dawn of the industrial revolution.

Recent simulations using the Community Earth System Model (CESM) indicate that a tipping event of the Atlantic Meridional Overturning Circulation (AMOC) would cause Europe to cool by several degrees. This AMOC tipping event was found under constant pre-industrial greenhouse gas forcing, while global warming likely limits this AMOC-induced cooling response. Here, we quantify the European temperature responses under different AMOC regimes and climate change scenarios. A strongly reduced AMOC state and intermediate global warming (C, Representative Concentration Pathway 4.5) has a profound cooling effect on Northwestern Europe with more intense cold extremes. The largest temperature responses are found during the winter months and these responses are strongly influenced by the North Atlantic sea-ice extent. Enhanced North Atlantic storm track activity under an AMOC collapse results in substantially larger day-to-day temperature fluctuations. We conclude that the (far) future European temperatures are dependent o

the rapid rises in global military spending threaten climate action, undermining our collective security. In a new joint paper we explore how everything from direct emissions to diverted climate finance are threatening SDG 13 on Climate action.

Militaries are huge energy users whose greenhouse gas emissions (GHG) make a significant contribution to the climate crisis. However, countries do not systematically record and report their military emissions so the real share of this source of emissions remains unclear. The Conflict and Environment Observatory (CEOBS) and Scientists for Global Responsibility estimate that everyday military activity could be responsible for around 5.5% of global emissions, meaning that if the world’s militaries were a country, they would be the fourth largest emitter in the world.6 Furthermore, as military spending increases and the rest of society decarbonises, that proportion is set to rise.

L’Organisation Météorologique Mondiale (OMM) publie ses prévisions climatiques pour les cinq prochaines années, 2025-2029. Selon l’OMM, les températures de la terre oscilleront entre +1.2°C et + 1.9°C, ce qui nous amène très près de 2°C de réchauffement en 2030 (OMM). Nous serons alors proches du climat annoncé pour la France à 4°C.

Societies increasingly rely on scientists to guide decisions in times of uncertainty, from pandemic outbreaks to the rise of artificial intelligence. Addressing climate change is no different. For governments wanting to introduce ambitious climate policies, public trust in climate scientists is pivotal, because it can determine whether voters support or resist those efforts.

Small particulate matter (PM2.5) in air pollution raises the risks of respiratory problems, cardiovascular disease, and even cognitive decline. Heat waves, which are occurring more often with climate change, can cause heatstroke and exacerbate conditions such as asthma and diabetes. When heat and pollution coincide, they can create a deadly combination.

Earth’s albedo (reflectivity) declined over the 25 years of precise satellite data, with the decline so large that this change must be mainly reduced reflection of sunlight by clouds. Part of the cloud change is caused by reduction of human-made atmospheric aerosols, which act as condensation nuclei for cloud formation, but most of the cloud change is cloud feedback that occurs with global warming. The observed albedo change proves that clouds provide a large, amplifying, climate feedback. This large cloud feedback confirms high climate sensitivity, consistent with paleoclimate data and with the rate of global warming in the past century.