Focus Climat

Les chiffres sont tombés mercredi, et ils sonnent comme un verdict sans appel. L’observatoire européen Copernicus et l’institut américain Berkeley Earth ont confirmé simultanément ce que de nombreux climatologues redoutaient : pour la première fois dans l’histoire des mesures, la température moyenne mondiale sur trois années consécutives dépasse de 1,5°C le niveau préindustriel. Cette limite, inscrite comme objectif le plus ambitieux de l’accord de Paris en 2015, n’était pas censée être franchie avant plusieurs décennies. Elle vient de céder en moins de trois ans.

L'année 2025 a été la troisième année la plus chaude jamais enregistrée dans le monde, ont annoncé mercredi l'observatoire européen Copernicus et l'institut américain Berkeley Earth, pour qui 2026 devrait rester à des niveaux historiquement hauts. Le thermomètre mondial affiche depuis trois ans des niveaux jamais vus à l'échelle de l'humanité, avec une moyenne sur la période supérieure de 1,5°C au niveau préindustriel (1850-1900), note Copernicus dans son bilan annuel. "La hausse brutale enregistrée entre 2023 et 2025 a été extrême et suggère une accélération du rythme du réchauffement climatique", estiment séparément les scientifiques de Berkeley Earth, aux Etats-Unis.

A new international analysis published in Advances in Atmospheric Sciences on 9 January finds that the Earth's ocean stored more heat in 2025 than in any year since modern measurements began. The finding is the result of a major international collaboration led by the Institute of Atmospheric Physics at the Chinese Academy of Sciences, involving more than 50 scientists from 31 research institutions worldwide. The 2025 heat increase was 23 Zetta Joules (23,000,000,000,000,000,000,000 Joules of energy), which is equivalent to ~37 years of global primary energy consumption at the 2023 level (~620 Exa Joules per year). The assessment combines data from major international data centers and independent research groups, including three observational products (Institute of Atmospheric Physics at the Chinese Academy of Sciences; Copernicus Marine; and NOAA/NCEI) and an ocean reanalysis (CIGAR-RT) from three continents: Asia, Europe, and America. These groups confirm that the 2025 ocean heat content (OHC) reached the h

The datasets used to diagnose the modern history of the planet’s climate — and to proclaim that the world is now very near to 1.5 degrees Celsius (2.7 degrees Fahrenheit) of warming — typically begin with the year 1850. The new one goes all the way back to 1781. This extended time frame matters because greenhouse gases in the atmosphere increased 2.5 percent between 1750 and 1850, enough to have caused some warming that the data hasn’t accounted for.

Glacial earthquakes are a special type of earthquake generated in cold, icy regions. First discovered in the northern hemisphere more than 20 years ago, these quakes occur when huge chunks of ice fall from glaciers into the sea. Until now, only a very few have been found in the Antarctic. In a new study soon to be published in Geophysical Research Letters, I present evidence for hundreds of these quakes in Antarctica between 2010 and 2023, mostly at the ocean end of the Thwaites Glacier – the so-called Doomsday Glacier that could send sea levels rising rapidly if it were to collapse.

Around 56 million years ago, Earth suddenly got much hotter. Over about 5,000 years, the amount of carbon in the atmosphere drastically increased and global temperatures shot up by some 6°C.

We are hurtling toward climate chaos. The planet's vital signs are flashing red. The consequences of human-driven alterations of the climate are no longer future threats but are here now. This unfolding emergency stems from failed foresight, political inaction, unsustainable economic systems, and misinformation. Almost every corner of the biosphere is reeling from intensifying heat, storms, floods, droughts, or fires. The window to prevent the worst outcomes is rapidly closing. In early 2025, the World Meteorological Organization reported that 2024 was the hottest year on record (WMO 2025a). This was likely hotter than the peak of the last interglacial, roughly 125,000 years ago (Gulev et al. 2021, Kaufman and McKay 2022). Rising levels of greenhouse gases remain the driving force behind this escalation. These recent developments emphasize the extreme insufficiency of global efforts to reduce greenhouse gas emissions and mark the beginning of a grim new chapter for life on Earth.

22 of the planet’s 34 vital signs are at record levels, with many of them continuing to trend sharply in the wrong direction. This is the message of the sixth issue of the annual “State of the climate” report. The report was prepared by an international coalition with contribution from the Potsdam Institute for Climate Impact Research (PIK) and led by Oregon State University scientists. Published today in BioScience, it cites global data from the Intergovernmental Panel on Climate Change (IPCC) in proposing “high-impact” strategies.

Four key parts of the Earth’s climate system are destabilising, according to a new study with contributions from the Potsdam Institute for Climate Impact Research (PIK). Researchers analysed the interconnections of four major tipping elements: the Greenland ice sheet, the Atlantic meridional overturning circulation (AMOC), the Amazon rainforest and the South American monsoon system. All four show signs of diminished resilience, raising the risk of abrupt and potentially irreversible changes.

Predictably, soon, most young people will reject extremist views. This will be none too soon because it is the essential step leading to global political leadership that appreciates the threat posed by climate’s delayed response to human-made changes of Earth’s atmosphere. Then the annual fraud of goals for future “net zero” emissions announced at United Nations COP (Conference of Parties) meetings might be replaced by realistic climate policies. It is important, by that time, that we have better knowledge of the degree and rate at which human-made forcing of the climate system must be decreased to avoid irreversible, unacceptable consequences.

Earth’s average temperature rose more than 1.5°C above pre-industrial levels in 2024 for the first time – a critical threshold in the climate crisis. At the same time, major armed conflicts continue to rage in Ukraine, Gaza, Sudan and elsewhere. What should be increasingly clear is that war now needs to be understood as unfolding in the shadow of climate breakdown. The relationship between war and climate change is complex. But here are three reasons why the climate crisis must reshape how we think about war.

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

There is rising concern that several parts of the Earth system may abruptly transition to alternative stable states in response to anthropogenic climate and land-use change. Key candidates of such tipping elements include the Greenland Ice Sheet, the Atlantic Meridional Overturning Circulation, the South American monsoon system and the Amazon rainforest. Owing to the complex dynamics and feedbacks between them via oceanic and atmospheric coupling, the levels of anthropogenic forcing at which transitions to alternative states can be expected remain uncertain. Here we demonstrate how such interactions can generate spurious signals and potentially mask genuine signs of destabilization. We further review and present observation-based evidence that the stability of these four tipping elements has declined in recent decades, suggesting that they have moved towards their critical thresholds, which may be crossed within the range of unmitigated anthropogenic warming. Our results call for better monitoring of these ti

New research reveals Earth's natural carbon sink nearly collapsed in 2024, absorbing almost zero human CO₂ emissions.

The world is losing fresh water at an unprecedented rate, two decades' worth of satellite data has revealed. Measurements from NASA's twin GRACE satellites and GRACE follow-on missions have shown that since 2002, the amount of land suffering from water loss has been increasing year on year by twice the area of the state of California. That includes the loss of water from surface reservoirs such as lakes and rivers and underground aquifers, which are an important source of drinking water around the globe.

As civilization advanced, humans developed tools that allowed us to shield ourselves from the natural cycles that once defined our lives. Fire helped us escape the cold. Irrigation let us shape landscapes around our needs. Walls and weapons kept predators at bay. Over time, these inventions accumulated into infrastructure, then ideology. The more protected we became, the more separated we felt...

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 the last 80 years, Thwaites has been losing more water through melting than it’s been gaining in snow.Half a metre of sea-level rise would submerge large parts of Asia’s coastal cities including Manila and Bangkok, as well as sizeable chunks of the Netherlands and the east of England. It’s also half of the sea-level rise needed to begin flooding Manhattan.

Why is the Trump Administration trying to kill a small space science institute in New York City? Explanation begins with Galileo’s method of scientific inquiry and ends with the role of special interest money in the United States government. Galileo improved the telescope, allowing clearer observations of the planets and the Sun. Galileo differed from his peers, as he was unafraid to challenge authority. He claimed that the world should be understood based on observations, and he spoke directly to the public. He obtained philanthropic support for his observations and openly described the conclusion that Earth was not the center of the solar system – Earth revolved around the Sun.

Real world measurements of how much extra heat the Earth is trapping are well beyond most climate models. That’s a real problem.