In questi giorni, seppure in un contesto di mezzi di informazione impegnati a normalizzare un caldo del tutto fuori dalla norma, ha fatto capolino l’allarme per la temperatura del Mar Mediterraneo che non è stato possibile definire altrimenti che eccezionale.
La stima del Copernicus Climate Change Service è che nel mese di giugno il Mediterraneo ha avuto una temperatura media superiore di 6 gradi (che in alcuni casi diventano addirittura 8) rispetto a quella degli ultimi 40 anni. Nei primi giorni di agosto al largo dell’isola di Maiorca sono stati raggiunti i 33,02 °C, al largo di Agropoli (in provincia di Salerno) i 30,9 °C.
Questo – se guardiamo alle cause immediate – è il risultato di un inverno e una primavera con temperature sopra la norma, di un lungo periodo di alta pressione e di uno scarso, se non scarsissimo, ricambio di acque fresche provenienti dall’Atlantico. Ed è probabile che il prolungamento ulteriore dell’alta pressione e di alte temperature atmosferiche spingano la temperatura delle acque ancora più su.
Le conseguenze di questo processo che è in via di consolidamento da tempo (il 2026 sarà il quinto anno di seguito con temperature record del mar Mediterraneo) sono sotto molti aspetti già evidenti: peggioramento della qualità delle acque (con diminuzione dell’ossigeno e varie alterazioni chimiche e biologiche), mortalità delle specie più sensibili, produzione anomala di alghe, crisi per pesca e acquacoltura. E gli effetti più estremi dovrebbero aversi in autunno, con un’alta probabilità di nubifragi, trombe d’aria e violenti temporali per l’arrivo di aria fresca su acque marine ancora molto calde.
Benché il Mediterraneo sia particolarmente esposto al riscaldamento delle sue acque, questo fenomeno è globale. E – secondo il parere di alcuni autorevoli scienziati, tra cui il tedesco Stefan Rahmstorf – proprio la variazione di temperatura dell’acqua marina, insieme con la variazione della sua salinità, sta gettando le premesse per un collasso del “sistema di circolazione oceanica” (l’Atlantic meridional overturning circulation, o Amoc) che distribuisce il calore dai tropici all’Atlantico settentrionale. Questo collasso (in sostanza un venir meno della “circolazione atlantica”) era ritenuto soltanto fino a ieri molto improbabile; l’incalzare dei cambiamenti dello stato delle acque non lento e lineare, ma a scatti e crescente intensità, ha portato gli scienziati degni di questo nome a lanciare il 15 aprile scorso un allarme che il pubblicista Georges Monbiot ha rilanciato qualche settimana fa su “The Guardian”.
Le risposte di Monbiot al perché i governi non ritengano prioritario affrontare di petto un simile pericolo catastrofico – che produrrebbe un tracollo delle temperature verso il basso nell’Europa settentrionale, rendendo l’agricoltura impossibile nel Regno Unito, un rialzo record della temperatura dell’oceano Antartico e cambiamenti radicali nel ciclo delle acque dell’Amazzonia – hanno di solito, e anche questa volta, un che di ingenuo. Ma la sua conclusione, fortemente polemica verso la scienza economica ufficiale dei premi Nobel e verso l’élite capitalistica globale, merita di essere richiamata:
“Una setta di miliardari votata alla morte ha le dita strette intorno alla gola dell’umanità. Provoca e al tempo stesso minimizza la nostra crisi esistenziale. Gli oligarchi non sono solo un nemico di classe ma, come sono sempre stati, un nemico della società: poche migliaia di persone sono in grado di distruggere civiltà intere. Miliardi di persone contro miliardari, e la posta in gioco non potrebbe essere più alta di così”.
Qui di seguito i link al suo articolo in inglese e in italiano.
A catastrophic climate event is upon us. Here is why you’ve heard so little about it
Scientists say a crucial Atlantic system is more likely to collapse than previously thought. But the billionaire death cult that steers humanity’s destiny doesn’t do existential crisesThu 23 Apr 2026 08.00 CESTShare841
The poor and middle pay taxes, the rich pay accountants, the very rich pay lawyers – and the ultra-rich pay politicians. It’s not an original remark, but it bears repeating until everyone has heard it. The more money billionaires accumulate, the greater their control of the political system – which means they pay less tax, which means they accumulate more, which means their control intensifies.
They reshape the world to suit their demands. One of the symptoms of the pathology known as “billionaire brain” is an inability to see beyond their own short-term gain. They would sack the planet for a few more stones on the pointless mountain of wealth. And we can see it happening. Last week delivered the biggest news of the year so far, perhaps the biggest news of the century. But partly because billionaires own most of the media, most people never heard it. We might find ourselves committed to a civilisation-ending event before we even learn that such a thing is possible.
The news is that the state of a crucial oceanic circulation system has been reassessed by scientists. Some now believe that, as a result of climate breakdown changing the temperature and salinity of seawater, it is more likely than not to collapse. This system – known as the Atlantic meridional overturning circulation (Amoc) – delivers heat from the tropics to the North Atlantic. Recent research suggests that if it shuts down, it could cause both a massive drop in average winter temperatures in northern Europe and drastic changes in the Amazon’s water cycles. This could help tip the rainforest into cascading collapse and trigger further disaster.
Amoc’s shutdown is likely also to cause an acceleration of sea level rise on the east coast of the US, threatening cities. It could also raise Antarctic temperatures by roughly 6C and release a vast pulse of carbon currently stored in the Southern Ocean, accelerating climate catastrophe.
Even when the countervailing effects of generalised global heating are taken into account, a further paper proposes, the net impact in northern Europe would be periods of extreme cold – including events in which temperatures in London fall to -19C, in Edinburgh to -30C and in Oslo to -48C. Sea ice in February would extend as far as Lincolnshire. Our climate would change drastically, with the likelihood of far greater extremes, such as massive winter storms. Rain-fed arable agriculture would become impossible almost everywhere in the UK.
This shift, on any realistic human scale, would be irreversible. Its speed is likely to outrun our ability to adapt. Amoc shutdowns, driven by natural climate variability, have happened before. But not in the era of large-scale human civilisation.
The first paper proposing that Amoc might have an on-state and an off-state was published in 1961. Since then, many studies have confirmed the finding and explored potential triggers and likely implications. Until recently, Amoc collapse caused by human activity fell into the category of a “high impact, low probability” event, devastating if it happens, but unlikely to occur. Research over the past few years prompted a reassessment: it began to look more like a “high impact, high probability” event. Now, in response to last week’s paper, Prof Stefan Rahmstorf – perhaps the world’s leading authority on the subject – says the chances of a shutdown look like “more than 50%”. We could pass the tipping point, he says, “in the middle of this century”.
So why is this not all over the news? Why is it not the top priority for the governments that claim to protect us from harm? Well, in large part because oligarchic power has championed a model of climate impact that bears little relation to reality: that is, they have a hypothesis about how the world works that is completely detached from scientific findings. This model underpins official responses to the climate crisis.
It began with the work of the economist William Nordhaus, who sought to assess the economic effects of global heating. His modelling suggests that a “socially optimal” level of heating is between 3.5C and 4C. Most climate scientists see a temperature rise of this kind as catastrophic. Even 6C of heating, Nordhaus suggests, would cause a loss of just 8.5% of GDP. Climate science suggests it would look more like curtains for civilisation.
As the eminent economists Nicholas Stern, Joseph Stiglitz and Charlotte Taylor have argued, the mild effects Nordhaus forecasts are merely artefacts of the model he has used. For example, his modelling assumes that catastrophic risks do not exist and that climate impacts rise linearly with temperature. There is no climate model that proposes such a trend. Instead, climate science forecasts nonlinear impacts and greatly escalating risk. The likely impacts of high levels of heating include the inundation of major cities, the closure of the human climate niche (the conditions that sustain human life) across large parts of the globe, the collapse of the global food system and cascading regime shifts – that is, abrupt transitions in ecosystems – releasing natural carbon stores, potentially leading to a “hothouse Earth” in which very few survive. Never mind a few points off GDP: there would be no means of measurement and scarcely an economy to measure.
Bizarrely, the modelling also applies discount rates to future people: their lives, it assumes, are worth less than ours. In other words, it has taken a method used to calculate returns to capital and applied it to human beings. As the three economists point out, “it is very difficult to find a justification for this in moral philosophy.” Moreover, climate impacts disproportionately affect the poor – but under the models, their lives are also priced down.
Unsurprisingly, models of this kind, Stern, Stiglitz and Taylor note, have been seized on by “special interests” such as the fossil fuel industry to argue for minimal responses to the climate crisis. And it’s not just the oil companies. Bill Gates, who claims to want to protect the living planet, has given $3.5m (£2.6m) to a junktank run by Bjorn Lomborg, who has built his career on promoting Nordhaus’s model, thus helping to downplay the need for climate action. Nordhaus was awarded the Nobel Memorial prize for economics for his pernicious nonsense – and it is deeply embedded in government decision-making.
A billionaire death cult has its fingers around humanity’s throat. It both causes and downplays our existential crisis. The oligarchs are not just a class enemy but, as they have always been, a societal enemy: a few thousand people can destroy civilisations. It’s the billions v the billionaires, and the stakes could not possibly be higher.
- George Monbiot is a Guardian columnist
This article was amended on 23 April 2026 to remove an incorrect temperature conversion, which was added during the editing process.