This summer, the arctic burned. Boreal forests, usually caked in ice, were charred. Further south, from Quebec to Japan, hundreds of people dropped like scorched flies in the heat, as though under a giant magnifying glass. Across Europe, the same: deaths, drought and crop failure.

As heatwaves multiply in the future, so will heat-related deaths: 7,000 a year in the UK alone. Droughts will be more intense, leading to food shortages.

Often, when another climate change threshold is reached, a weary, soused contrarian emerges with exhortations to lighten up and enjoy the sunshine. It would be mistaken to take such scandal-seeking rhetoric at face value. It is superfluous: it exhorts people to do what they’re already doing. And for all its apparent cheeriness, it is a counsel of nihilistic despair. If you think something can be done, you will be serious and urgent rather than facetious. The catastrophists are the optimists here.

Climate change protests around the world Show all 25 1 /25 Climate change protests around the world Climate change protests around the world People rally to promote climate protection in Rome, Italy Climate change protests around the world Hundreds of demonstrators gather in front of City Hall in Los Angeles, California EPA Climate change protests around the world People hold hands to form a human chain during a gathering called by ecologist organisations in Marseille, southern France, to protest against global warming a day ahead of the United Nations Conference on Climate Change (COP21) held in Paris Climate change protests around the world Demonstrators clash with French riot police during protests on Place de la Republique, ahead of the COP21 World Climate Change Conference 2015 in Paris, France Climate change protests around the world Demonstrators clash with French riot police during a protest on Place de la Republique ahead of the COP21 World Climate Change Conference 2015 in Paris, France Climate change protests around the world A group of people perform during a rally to promote climate protection in Rio de Janeiro, Brazil Climate change protests around the world A protester sits next to his sign that reads 'Monsanto the Devil Incorporated ' as he joined hundreds of demonstrators who gathered in front of City Hall in Los Angeles, California EPA Climate change protests around the world Environmentalists dance during a protest near the Place de la Republique after the cancellation of a planned climate march following shootings in the French capital, ahead of the World Climate Change Conference 2015 (COP21), in Paris, France Reuters Climate change protests around the world People protest next to characters dressed as wild animals during a march against climate change near the Monument to the Revolution, in Mexico City AP Climate change protests around the world Protesters carries a banner while they take part in a protest about climate change at New York City Hall steps in lower Manhattan, New York Reuters Climate change protests around the world People take part in a protest about climate change around New York City Hall at lower Manhattan, New York Reuters Climate change protests around the world People rally to promote climate protection in Piazza Castello, Turin, Italy Climate change protests around the world A woman holds a globe during a protest for the global climate day in Lugano, Switzerland Climate change protests around the world Yemenis hold banners as they participate in the Global March for Climate in the old city of Sanaía, Yemen Climate change protests around the world Protesters dressed as Santa Claus take part in a protest about climate change at New York City Hall steps in lower Manhattan, New York Reuters Climate change protests around the world People gather at the Legislative Palace in Montevideo, during the Global Climate March to demand action on climate change telling world leaders on the eve of a crunch UN summit that there is "no planet B". From Sydney to London, humid Rio to chilly New York, at least 683,000 hit the streets in 2,300 events across 175 countries at the weekend, co-organiser and campaign group Avaaz said, calling it the largest number of people to protest over climate change all at once Getty Images Climate change protests around the world Climate change protests around the world Demonstrators participate in the Global March for Climate in Athens, Greece Climate change protests around the world A man wearing a Bernie Sanders mask leads hundreds of demonstrators who marched near City Hall in Los Angeles, California EPA Climate change protests around the world Patricia Hauser joined hundreds of demonstrators who gathered in front of City Hall in Los Angeles, California Climate change protests around the world A woman holds a poster of a sick Earth as she joined hundreds of demonstrators who gathered in front of City Hall in Los Angeles, California EPA Climate change protests around the world Hundreds of demonstrators march around City Hall in Los Angeles, California EPA Climate change protests around the world A demonstrator holds cut-out of US Democratic Presidential candidate Bernie Sanders as she joined hundreds of demonstrators who gathered in front of City Hall in Los Angeles, California EPA Climate change protests around the world George Patten holds a sign that reads 'No Fracking Ever!' as he joined hundreds of demonstrators who gathered in front of City Hall in Los Angeles, California EPA Climate change protests around the world Gabrielle Sosa wears 'Rising Sea Levels' sign as she joined hundreds of demonstrators who gathered in front of City Hall in Los Angeles, California EPA

To be fair, heatwave panic is silly season news. Sensationalism, though, is its own form of euphemism. For all the apocalyptic tone of heatwave reporting, it doesn’t go far enough. Not when the issue is human extinction.

The 2016 heatwave destroyed one third of coral in the Great Barrier Reef. Ocean life is responsible for most of the oxygen we breathe, and coral reefs are home to a quarter of all marine life, more productive than forest or savannah. The extinction of the reefs, a probability at this point, would sharply reduce the number of oxygen-producing phytoplankton. Coupled with the accelerating acidification of the ocean, warming is a threat to the air we breathe.

This is one of many dependencies supporting human life. Consider another example. Bee populations are recovering from colony collapse disorder. But now scientists find that warming is likely to cause the bees to die off rapidly anyway. Without their pollination work, 70 per cent of the crops that feed 90 per cent of the planet would fail. The era of cheap food is ending, as crop yields decline in a hotter planet.

We are already in the midst of a mass extinction event. The regularity with which new or threatened extinctions are announced – from the white rhinoceros to the lemur – is staggering. The background rate of extinction is 150-200 species a day. This is “biological annihilation”. Mass extinction is not new, but its speed is. The last such event took around 60,000 years. Now it’s happening in real time.

And there are accelerators built in to this crisis. The Arctic is already gone. By 2040, the ice will have melted for good. That entails the loss of species, not least of the polar bear. But it also means less solar radiation deflected, further warming the planet.

This is one reason why the crisis is far worse than we think. Paleoclimatologists have shown that past warming episodes show that there are mechanisms which magnify its effects, not represented in current climate models from the Intergovernmental Panel on Climate Change to the Paris Accords. The agreed “carbon budget”, even if anyone was adhering to it, will not keep temperatures within two degrees of the pre-industrial average.

The biggest obstacle to comprehending this is not the climate denial industry. It is what the sociologist Stanley Cohen called “implicatory denial”: recognising a problem but denying its consequences. This is far more insidious, particularly at the level of policymaking. The denial of politicians is easy to explain. An attack on fossil capitalism would be hugely destabilising for the world economy. As Andreas Malm has pointed out, it would destroy the worth of massive investments in plants, infrastructures, supply chains and dependent industries. It would burn a “planet of value”. The transition would require a collective mobilisation tantamount to world war. Few politicians want that.

What about everyday denial? What about the cheerfulness with which we just get on with things, and the resigned despair that implies? Certainly, there is a pervasive sense of political powerlessness. The work of the psychoanalyst Renee Lertzman suggests that, in addition to this, behind such resignation often lurks a thwarted mourning for worlds that have already been lost. Worlds of childhood memory, independence, adventure, possibility. Worlds perhaps bigger than those we find ourselves in. It’s a mourning stalled by ambivalence and guilt. This is one reason why lectures on consumerism, as if the problem was popular appetite, tend to be counterproductive.