Climate journal

A daily journal by Bruno Courtin devoted to climate, biodiversity, forests, oceans, water, energy and agriculture — literary observations and open questions.

Great Barrier Reef — a fifth mass bleaching event in ten years

What the aerial survey of March 2026 over Australia's Great Barrier Reef reveals is no longer a warning. It is a finding. The fifth episode of mass bleaching in ten years. 73% of reefs in the northern half affected. Certain areas show tissue mortality rates exceeding 40%. Coral bleaching is not the death of coral. It is its expulsion — in the literal sense. The polyp, under thermal stress, expels the symbiotic micro-algae that live within its tissues and give it its color. Without them, it turns white, translucent, spectral. Then, if it does not recover its symbionts within a few weeks, it dies. The immediate cause is straightforward: the temperature of the Coral Sea exceeded 30.5°C in February–March 2026, nearly two degrees above the seasonal average. The underlying cause is twofold: the global warming of the oceans, which absorb 90% of the Earth system's excess heat, and an El Niño current that was particularly pronounced that year. What makes this fifth episode different from the preceding ones is the absence of any recovery window. A coral reef needs approximately ten to fifteen years to rebuild its colonies after a mass bleaching event. Since 2016, episodes have followed one another every two or three years. The calendar of death no longer leaves room for any calendar of life. The consequences are physical, economic, and cultural. Physical: the Great Barrier Reef shields 2,300 kilometers of Australia's coastline from swells and cyclones. Economic: six billion Australian dollars per year and 64,000 jobs. Cultural: for the Aboriginal peoples of Queensland, the Coral Sea is an ancestral territory mapped across tens of thousands of years by the Dreaming. An observation, not a slogan: the Great Barrier Reef is not yet dead. But it is losing its capacity to be what it has always been — a living system on a geological scale. What will replace this slow calcareous architecture, no one yet knows. The sea, for its part, continues its work without asking our opinion.

Norway's Cold Corals — Invisible Gardens a Thousand Meters Down

Most readers associate coral with light, with warmth, with the turquoise waters of the tropics. They are right, for the most part. But there exists another family of corals, less photogenic yet equally ancient, that lives in absolute darkness, at depths between 200 and 1,500 meters, in waters whose temperature never exceeds 8 °C. These are the cold-water corals. And Europe harbors one of the largest concentrations in the world. Off the coast of Norway, on the continental shelf of the Norwegian Sea, lies the Sula Reef. Thirty-five kilometers long, up to thirty-five meters high. A calcareous architecture built slowly, colony by colony, principally by a species called *Lophelia pertusa*. This species grows at a rate of roughly one centimeter per year. A reef several meters tall is therefore, at the very least, several thousand years old. Certain cold-coral mounds in the North Atlantic, sampled by isotopic coring, began their construction more than eight thousand five hundred years ago — that is, before the pyramids of Giza. What these reefs shelter, we are only beginning to document. A biodiversity comparable, in species density, to that of tropical reefs: galatheids, demersal fish, rare sponges, endemic crustaceans. Cold-water reefs function as oases in a bathyal desert — they concentrate life where there would otherwise be almost none. The primary threat is no longer direct warming — these corals live too deep to be affected by surface temperature variations — but two other factors, more subtle and more difficult to regulate. The first: bottom trawling. A weighted net dragging across the seafloor at 700 meters depth destroys in a matter of hours what a colony took centuries to build. Images published by the Norwegian Institute of Marine Research (IMR) in 2025 show entire expanses crushed, reduced to gravel made of fragmented skeletons. The second: acidification. One third of the CO₂ we emit is absorbed by the oceans, where it converts into carbonic acid. At scale, this slowly dissolves calcium carbonate — precisely the material from which corals build their skeletons. Projections through 2100 indicate that North Atlantic waters will fall below the aragonite saturation threshold, a crystalline form of carbonate. In concrete terms: the sea will begin to *dissolve* reefs faster than they can form. Cold-water corals, which had survived every glaciation of the Pleistocene, may not outlast the twenty-first century. Norway placed part of the Sula Reef under protection in 2003, banning trawling over approximately 1,000 km². It is a beginning. But acidification is not something that can be regulated by national decree. It is the physicochemical consequence of our cumulative emissions, and it advances independently of local agreements. An observation, not a slogan: cold-water coral reefs are probably the oldest living ecosystem still functioning in European waters. We discovered them too late. There is no certainty that we will keep them.

Sahel — when rain becomes a riddle

In the Sahel, rain has never been regular. It has always obeyed long cycles, alternations of good years and bad, the climatic breathing that farmers in Niger, Burkina Faso, and Mali have known how to read for generations. But since 2020, that reading no longer suffices. The markers have blurred. Researchers at AGRHYMET, the regional agrometeorological monitoring centre, describe a phenomenon they call the "erasure of seasons." The main rainy season, which structured the cultivation of millet and sorghum from June to September, has shortened and fragmented. It now begins later, breaks off in the middle, then returns as brutal, short downpours that erode more than they irrigate. A Fulani farmer told me, through interview work conducted by a partner NGO: "Before, we knew when to sow. Now, we sow, we wait, the rain doesn't come, we sow again, sometimes three times before anything takes." What is at stake here is not only agricultural. It is cognitive. An entire culture of peasant knowledge, transmitted orally across centuries, finds itself unmoored from reality. The consequences are measured and grave: according to the WFP, 36 million people face acute food insecurity across the Sahel belt in 2026, compared to 20 million in 2019. Internal climate migrations are accelerating — from the rural north toward the urban areas of the south, where absorption capacity is overwhelmed. What strikes the observer is the disproportion. The Sahel has emitted, since the beginnings of the industrial era, a minuscule fraction of the greenhouse gases now disrupting its rainfall patterns. It is enduring a crisis of which it is not the principal author. This asymmetry between responsibility and exposure is arguably the deepest moral question of the contemporary climate. The matter is not one of aid — a paternalistic verb that implies hierarchy. It is one of acknowledging a debt. And of translating that debt, within international negotiations, into something other than announcements that never materialize.

Doggerland — when the North Sea reclaims its lost continent

Twelve thousand years ago, one did not cross the Channel. There was nothing to cross. Great Britain and continental Europe had not yet become two separate lands: between them stretched a vast territory of wet forests, slow rivers, and peat bogs, inhabited by Mesolithic tribes, wild boar, red deer, and aurochs. That territory, now submerged, is called Doggerland. British and Dutch archaeologists and geologists first suspected its existence in the 1930s, when trawlers working the Dogger Bank began hauling up in their nets fragments of bone, flint points, and antler harpoons. A genuine human settlement lay fifteen to twenty metres beneath the waves. What changes in 2026 is the cartographic precision. Acoustic survey campaigns conducted by the Europe's Lost Frontiers project, published by the University of Bradford, now reveal the fine-grained topography of this erased continent: river courses, deltas, hills, probable habitation sites. One can trace, across the seabed, the exact path of a river that flowed ten thousand years ago. It is a human landscape held in preservation, unlike anything found elsewhere on Earth — because the sea sealed it, rather than the plough or concrete. Doggerland did not vanish all at once. It was gnawed away over millennia by the gradual melting of the north-European ice sheets of the last glaciation. Around 6200 BCE, a sudden event likely completed the process: the Storegga submarine landslide, off the coast of Norway, is thought to have triggered a tsunami capable of submerging in a single stroke the last inhabited islands. What makes this archaeology particular to our own era is the mirror it holds up. Doggerland is the first great human civilisation swallowed by a rising sea driven by climate change. We know its artefacts — a few harpons, a few skulls. We will never know its myths, its songs, its mental maps of the land. An observation, in lieu of a lesson: today's coastal populations — Bengal, the Nile Delta, Louisiana, Bangladesh, the Netherlands, Marseille in a few centuries — are living, at an accelerated pace, what Doggerland lived across three millennia. The difference is that we know. And that this knowledge has not yet taught us how to act.

Mammoth (Iceland) — Direct Air Capture finally changes scale

Forty minutes from Reykjavik, on a wind-swept basalt plateau near the Hellisheiði geothermal plant, there exists an industrial facility that draws in air and extracts carbon dioxide from it. It is called Mammoth. It is operated by the Swiss company Climeworks. In 2026, it is the largest direct air capture (DAC) unit in the world. The principle is straightforward to describe, complex to achieve at scale. Large fans push ambient air through cartridges containing absorbent materials — amines fixed to a solid support. CO₂ binds chemically to these materials. Once saturated, the cartridges are heated to around 100 °C — using residual heat from the neighbouring geothermal plant — and the concentrated CO₂ is released, captured, then injected into the underlying basalt, where it mineralises into carbonate within a few years through the CarbFix process, an Icelandic technology co-developed by Reykjavík Energy and the University of Iceland. What sets Mammoth apart from its predecessor Orca (commissioned in 2021, with a capacity of 4,000 tonnes of CO₂ per year) is the scale factor. Mammoth, operational since May 2024, crossed the threshold of 36,000 tonnes per year in July 2026 following a calibration phase. The target by 2027: bring annual capacity to 40,000 tonnes. The raw figures remain, it must be said, modest relative to the scale of the problem. Global human CO₂ emissions amount to approximately 37 billion tonnes per year. In its current state, Mammoth captures the equivalent of just under one minute of those emissions. To offset a full year, roughly one million Mammoths would be needed. What matters, therefore, is not absolute performance but trajectory. The cost per tonne captured has fallen from 1,200 dollars in 2021 (Orca) to around 500 dollars in 2026 (Mammoth), with projections of 200–300 dollars by 2030 for the next generation of plants. At that level, DAC becomes economically viable for offsetting certain residual industrial emissions that cannot be directly eliminated — cement, long-haul aviation, primary steel. It is necessary, however, to state clearly what DAC is not. It is not a solution that would relieve us of the obligation to reduce our emissions. It is a costly, energy-intensive, late-arriving complement — and one that is in all likelihood unavoidable if the targets of +1.5 °C or +2 °C are to be met. Any serious climate policy now rests on two pillars: massively decarbonising primary emissions, and capturing what remains. To neglect either one is to forfeit both. An open question for this journal: Icelandic DAC is funded in part by corporate clients — Microsoft, Stripe, JPMorgan — who purchase captured tonnes as offsets. Will this voluntary market be sufficient to bring the technology to the scale of one million tonnes? Or will a binding international regulatory framework be required, comparable to what is being discussed for aviation? The answer to that question will likely determine whether Mammoth remains an engineering feat, or becomes the prototype for a new planetary infrastructure.

Insects of Europe — the silent collapse no one hears

There is a very simple way to measure the biodiversity of a landscape: drive fifty kilometers on a summer evening and look at the windshield. Thirty years ago, you had to stop to wipe it clean. Today it often stays nearly spotless. This observation, long dismissed as anecdotal, has a scientific name — the "windshield effect" — and it is now confirmed by decades of rigorous measurement. The Krefeld study, first published in 2017 by the entomological society of the Rhineland, established a figure that remains, ten years on, one of the most disturbing in contemporary ecology: 75% of flying insect biomass lost over thirty years in protected areas of Germany. Not 75% of threatened species, not 75% of rare individuals. 75% of total insect mass, in nature reserves that were supposed to be sanctuaries. Updates published in 2025 by the iDiv network in Leipzig and by INRAE in France confirm that the trend has not reversed. It has in fact extended to groups previously thought more stable: soil beetles in forest ecosystems, pollinating hymenoptera, moths. Some European bumblebee populations have declined by 40% in ten years. Swallows, bats, swifts — all the vertebrates that live on insects in flight — are collapsing in parallel, at rates that leave little room for causal ambiguity. The factors are multiple: persistent neonicotinoid pesticides in soils, agricultural uniformization, the disappearance of hedgerows and refuge zones, nocturnal light pollution, land artificialization, and of course climate — the thermal cycles of insects are desynchronized from the floral cycles that feed them. What makes this crisis particular is its cultural invisibility. A disappearing bear makes the front page. An endangered tiger mobilizes NGOs. An insect does not. It is small, ugly, it stings, it clings. We have built no emotional narrative around it. Yet it is precisely this small people — 80% of terrestrial animal biomass, the invisible infrastructure of the living world — that makes possible nearly everything we eat and breathe. A gardener from Alsace confided to me recently: "I no longer hear the crickets in the evening. I grew up with that sound, and I no longer hear it." The silence rising from the European countryside is not a poetic metaphor. It is a biophysical signal. An observation, in the absence of action: we are probably the first generation that will watch a landscape emptied of its insects within a single lifetime, without this being recognized as a historical event.

Noor Ouarzazate — when the Moroccan desert generates electricity at night

There exists, three hours' drive southeast of Marrakech, on a desert plateau ringed by the ridges of the High Atlas, a solar power plant unlike any other. Seen from the sky, it is an immense black eye of twenty-five square kilometres, bristling with six hundred and fifteen thousand mirrors arranged in concentric circles around three towers and a parabolic field. Official name: the Noor Ouarzazate complex. Installed capacity: 580 MW. What sets Noor apart from conventional photovoltaic farms is its technology. This is concentrating solar power — CSP. The mirrors do not produce electricity directly. They focus sunlight onto a heat-transfer fluid — in this case, molten salts heated to 565 °C — which stores thermal energy throughout the day and feeds a steam turbine. The critical point is the night. Thanks to thermal storage, Noor Ouarzazate continues to generate electricity for up to seven hours after sunset. What photovoltaics cannot yet accomplish at scale, molten-salt CSP has been delivering since 2018. The Drâa desert now powers, well past midnight, the air conditioners of Casablanca and part of the grid serving Rabat. The installation, financed in part by a German-Moroccan consortium involving the World Bank and KfW, cost approximately 2.3 billion euros. It employs six hundred people on a permanent basis. It has allowed Morocco to reduce its historically substantial fossil fuel imports by several percentage points since 2020. An expansion project, Noor V, is intended to double capacity by 2029. What holds me back from writing this entry in a triumphalist tone is the context. CSP consumes water — to cool the condenser — and the Drâa desert is already under severe hydrological stress. Local populations, including Berber communities, have not always been involved in the decisions or in the economic benefits. Finally, the question of transmitting electricity to Europe — the Xlinks project toward the United Kingdom, submarine cables from Tan-Tan — raises legitimate concerns: what model of energy cooperation are we building with the African continent? A post-colonial extraction dressed up as a green transition, or a genuine industrial partnership? An observation, not a slogan: Noor Ouarzazate demonstrates that the energy transition is not a technical utopia. It is an achievable undertaking. What remains uncertain are the political and social terms under which it is deployed.

Siberia — the permafrost collapsing faster than predicted

Permafrost, the permanently frozen ground that covers a quarter of the landmasses of the northern hemisphere, holds approximately 1,500 billion tonnes of organic carbon — nearly twice the carbon currently present in the atmosphere. As it thaws, some of that carbon is released as CO₂, some as methane, a greenhouse gas roughly 28 times more potent over a hundred years. What the latest measurements published in 2026 by the Nunataryuk consortium and the Melnikov Institute in Yakutsk reveal is that the rate of thaw has exceeded the IPCC's 2021 median projections. In Yakutia, Chukotka, and northwestern Siberia, zones that were previously stable down to fifteen metres in depth now show active layers — that is, layers that thaw in summer — reaching two to three metres. The visible signs are striking. Thermokarsts — ground subsidence caused by the melting of interstitial ice — are multiplying. The Batagaika crater, in the Yana basin, expands by 20 to 30 metres per year. Roads are collapsing. Buildings constructed on stilts, once firmly anchored in hard ground, are tilting and cracking. The tarmac in Yakutsk heaves in slabs. But the invisible manifestation is more troubling still. It is chemical. The carbon now escaping from the soil through bacterial respiration — the microorganisms of the permafrost, dormant for tens of thousands of years, are awakening and digesting the trapped organic matter. This process creates a positive feedback loop: warming causes thawing, thawing releases CO₂ and methane, and those gases amplify the warming. What climatologists fear is the crossing of a threshold — a point at which the release becomes self-sustaining, independent of our emissions. We do not know exactly where that threshold lies. We know that it exists. We know that we are closer to it than we were in 2015. An observation, in the absence of an answer: the climate question is playing out increasingly in places invisible to the ordinary eye. No one, outside of Russian scientists and the indigenous Sakha, Evenk, and Yukaghir populations, sees Siberia changing. And yet, what is happening there will not stay in Siberia.

Amazonia 2026 — the forest that no longer exports enough rain

The Amazonian forest does not merely shelter life. It manufactures atmospheric weather. Each large tree transpires roughly one thousand litres of water per day. Multiplied across hundreds of billions of specimens, these vapours form what climatologists call "flying rivers" — flows of moisture that cross the continent from east to west and fall as rain over the Andes, Paraguay, and Argentina. Yet these rivers are diminishing. INPE, the Brazilian institute for space research, published measurements in June 2026 that confirm what had been suspected since 2023: the south-eastern Amazon has crossed its hydrological tipping point. Precipitation there has declined by 15 to 20 percent over a decade. Certain basins now go several months without effective rainfall, whereas historically they received 200 mm per month over the same period. What I am observing here is not only the disappearance of trees. It is a shift in the planetary water regime. A forest that no longer returns enough water to the atmosphere ceases to be a forest and becomes, slowly, a savanna. This is called "savanisation." The process is self-referential: less forest, less rain, less forest. The consequences extend beyond Brazil. The crops of the Río de la Plata basin — soy, wheat, maize — depend on the rains that Amazonia sends back. Buenos Aires itself receives a portion of its water from the Amazonian flying rivers. The food security of one-fifth of South America therefore rests on foliar transpiration that ongoing deforestation continues to sever. One question remains open: what is to be done with a forest that is no longer merely a national patrimony, but a regulatory organ of the regional climate? Brazilian sovereignty over Amazonia is a legitimate political principle. The atmospheric role of this forest is a physical fact. The two do not coincide — and that is arguably one of the most difficult challenges of the century ahead.

The Loire Running Dry — When French Nuclear Power Meets Its Water Ceiling

There is, in the Loire Valley, an equation that never appears in electoral speeches, yet one that nonetheless structures our energy independence: without water, no nuclear power. Or more precisely: without water that is sufficiently cool and sufficiently abundant, no nuclear power at full capacity. Four plants line the river: Belleville, Dampierre-en-Burly, Saint-Laurent-des-Eaux, Chinon. Together they account for nearly 14 electrical gigawatts and supply, in an average year, approximately 12% of France's nuclear output. All of them use Loire water to cool their secondary circuits — either in open-cycle mode (Chinon, partially), or in closed-cycle mode via cooling towers, or by combining the two. Every summer since 2019, EDF has been compelled to apply for temporary exemptions from the Nuclear Safety Authority in order to continue discharging water into the river at temperatures above the regulatory limit — failing which, output would have to be reduced, or certain reactor units shut down altogether. The reason is straightforward: when the river is already at 27 °C upstream, one cannot discharge water at 30 °C into it without risking thermal stress on aquatic fauna — fish, invertebrates, larvae. The summer of 2025 had already set a record: twelve exemption requests, several of them extended through September. The summer of 2026 is shaping up to be more difficult still. The Loire's flow rate at Gien fell, in July, to 60 m³/s — less than half the historical average. At such levels, the thermal margin for maneuver is narrow. At Belleville, two reactor units were forced to reduce their load to 70% for several days in June. What strikes the attentive observer is the systemic nature of the problem. French nuclear infrastructure was designed for a climate that no longer exists. The hydraulic models of the 1970s and 1980s, upon which thermal discharge authorizations rest, assumed average summer flow rates that were still plausible at the time. They no longer are. Each year, EDF's forward-looking scenarios are revised downward. Each year, the gap between the installed fleet and the available water supply widens. Two responses currently coexist: in the short term, multiplying exemptions and operating in degraded mode each summer. In the medium term, contemplating a partial shift in cooling systems — toward air, toward hybrid configurations — but this is costly, takes years to build, and reduces thermal efficiency. In the long term, the question stands: can a new generation of reactors (the EPR2s, the SMRs) be planned without having resolved the water constraint that already weighs on the current generation? An open question for this journal: French energy sovereignty rests on an implicit assumption of freshwater availability. That assumption, never until now made explicit, is collapsing before our eyes. When will we place it at the center of public debate?

Alsace, Summer 2026 — a region whose climate changes within a generation

The summer of 2026 is shaping up to be a hard one in Alsace. Seasonal forecasts confirm what the old vines already sense: heatwaves are no longer anomalies — they are becoming seasons. In Sélestat, in Colmar, in Strasbourg, temperatures regularly exceed 38 °C by late June. The nights no longer cool. Bodies no longer recover. Hospitals adjust their geriatric protocols the way one lets out a garment that has grown too tight. What I am watching is not the meteorological statistics — others do that better than I do. What I am watching is the slow reorganization of daily life: working hours shifted to dawn, schools closing earlier, markets retreating beneath the arcades, balconies armored with reed screens, rivers thinning until they reveal stones unseen for a century. Alsace is not Provence. It has never thought of itself as Mediterranean. And yet it is precisely a Mediterranean climate that is settling in, silently, between the Ried and the Vosges. The twentieth-century forestry schemes, planted with fast-growing conifers, are drying out en masse: Douglas fir, Norway spruce, silver fir. They are being replaced, gradually, by holm oaks, Montpellier maples, species that, thirty years ago, belonged to another world. An open question for this journal: when a region's climate changes within a single generation, what remains of the cultural identity bound to its landscape? Sauerkraut, Riesling, the Black Forest seen from Turckheim — how many of these markers will survive the decade?

The Beeches of the Vosges — Chronicle of a Farewell

The beeches of the Vosges do not die all at once. They retreat. They dry out branch by branch, shed their leaves on one side before slowly subsiding on the other, as though they were trying to remain standing out of habit rather than strength. This summer of 2026, in the massif stretching between the Donon and the Grand Ballon, forest rangers are recording cluster mortalities that can no longer be dismissed as incidental. It is no longer isolated specimens that are falling. Entire stands are stripping bare simultaneously, slope after slope, elevation after elevation — first the 400–600 metre range, now up to 800. The beech is a tree of cool places. It favors slow mists, long winters, temperate summers. It bears repeated drought poorly. Three consecutive years of water deficit — 2023, 2025, 2026 — have pushed it beyond its adaptive margin. Its roots, shallow by nature, no longer find water at the depths they once did. Photosynthesis stops earlier in the season. Reserves are not replenished. And to drought are now added bark beetles, opportunistic fungi, increasingly violent storms. What I am witnessing here is not only the disappearance of a species. It is the disappearance of a landscape. The beech has shaped the Vosges as much as the pink sandstone or the ridgelines. It holds the soil, produces humus, shelters ferns, structures the light beneath its pale leaves. A beech forest in summer is a green cathedral crossed by shafts of sunlight. It has a particular acoustics — the leaves rustle with a delicacy unlike anything else. When a beech dies, it is not only a tree that goes. It is a fragment of collective memory, a landmark on a walk, a midday shade, an autumn smell, a color from late October. Foresters are replanting — but with what? Sessile oaks, downy oaks, Montpellier maples, small-leaved lindens. Species more tolerant of heat, but ones that will no longer make the Vosges what they were. And the question that remains, unspoken, beneath these replanting plans: how many generations will it take for these new trees to become, in their turn, a beloved landscape?

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