How long​ do we have left, and how bad will it get? David Wallace-Wells opens his book with a short, sharp reality check: ‘It’s worse, much worse, than you think.’ All the news is bad. Marshalling research from across the sprawling field of climate studies, Wallace-Wells paints a picture of disastrous change on an almost incomprehensible scale. Transformations that will have consequences for thousands of years to come are already being expressed in sudden crises that spring up overnight. The changes are at once planetary and minute, affecting everything from the earth’s variable ability to reflect light from the sun to the microbes inside your body. Everything, it seems, is dissolving.

The book’s focus is on the most direct effects of global warming – hotter temperatures, rising seas, extreme weather and so on – as well as what these effects mean for humanity. Wallace-Wells leaves out much of our disastrous impact on the natural world. He doesn’t dwell on biodiversity loss, for instance, or the details of the mass extinction that we are by all accounts now living through, though he reminds us that of the five previous mass extinctions, only the most recent was caused by an asteroid. What was responsible for the other four? ‘Climate change produced by greenhouse gas.’ The deadliest occurred 250 million years ago, at the end of the Permian period, when 96 per cent of life on earth was wiped out. High levels of carbon dioxide in the atmosphere led to around 5°C of warming, which in turn triggered the release of methane – a much more powerful greenhouse gas – and possibly highly toxic and ozone-destroying hydrogen sulphide, produced by the anaerobic green sulphur bacteria that began to thrive in the warm oceans. We are currently adding carbon to the atmosphere at a rate ‘considerably faster’ than it took to cause this near-total erasure of complex life. ‘By most estimates,’ Wallace-Wells writes, ‘at least ten times faster.’ We may not be at anything like end-Permian levels yet, but the parallels are clear. The Intergovernmental Panel on Climate Change (IPCC) predicts that if emissions continue to rise at the current rate, the earth could experience as much as 4.5°C of warming by 2100. Permafrost in the Arctic is already melting, with the potential to release large quantities of methane, while the hydrogen sulphide that is thought to have ‘capped the end-Permian extinction, once all the feedback loops had been triggered’, is currently ‘bubbling out of the sea’ along a thousand-mile stretch of the Namibian coast, where green sulphur bacteria have caused a vast oceanic dead zone, devoid of oxygen and life.

It’s by no means the only one. There are now more than four hundred such dead zones in the world’s oceans, totalling an area the size of Europe. Most cluster around cities and river mouths, where the combination of warming waters, sewage pollution and fertiliser run-off causes blooms of algae whose decay leaches oxygen from the water. Others are caused by upwellings of the green sulphur bacteria, which has survived from a primordial planetary era before oxygen, waiting in the deep ocean for a chance to turn the seas back into a toxic microbial stew. Warmer seas and the subsequent changes to ocean currents mean their chance may be coming. The Baltic Sea now contains a layer of anoxic water all year round; the Gulf of Mexico dead zone is nine thousand square miles in size; it’s possible that the recently discovered dead zone in the Arabian Sea is large enough to consume the entire Gulf of Oman. Dead zones are examined briefly by Wallace-Wells in a chapter called ‘Dying Oceans’; only briefly, because he also has to consider ocean acidification, ocean warming, coral bleaching and the attendant die-offs of ocean life, as well as the slowing and potential failure of the Gulf Stream and other currents whose movements are intimately tied to regional climate. Should this last come to pass, the results would be ‘inconceivably catastrophic’. The Gulf Stream has already slowed by 15 per cent, something which hasn’t happened for at least a thousand years. A paper from 2018 suggests that the vast ocean circulation current is moving at its slowest rate for 1500 years. According to most global warming scenarios, this wasn’t supposed to happen for another hundred years.

‘Dying Oceans’ is one of 12 chapters discussing what Wallace-Wells calls the ‘elements of chaos’. Each is dedicated to a particular aspect of what we can expect in a warming world, from simple increases in temperature to crop failure, freshwater shortages, and violent and unpredictable weather, as well as secondary features such as greater migration and an increased incidence of wars. The US military is ‘obsessed with climate change’, Wallace-Wells writes, and the Pentagon is actively ‘planning for a new era of conflict governed by global warming’. They are not alone in thinking this way. The Chinese government is responding to the anticipated loss of military and naval bases in the rising Pacific by creating militarised artificial islands in the South China Sea, ‘a dry run, so to speak, for life as a superpower in a flooded world’. A new era of geopolitical contest looms, and it sounds like science fiction: end-time resource wars on a dying planet.

The Uninhabitable Earth is an example of the class of writing the eco-philosopher Timothy Morton has described as ‘ecological information data dump’: quantities of frightening and confusing information, mostly out of date by the time of publication, ‘shaking your lapels while yelling disturbing facts’. Morton believes this approach is unhelpful, and that it is essentially a symptom of the diffuse psychological pain caused by climate change – an attempt to prepare us for what has in fact already happened. And most of what Wallace-Wells describes has already happened. The phenomena he documents in the first part of the book are not hypothetical outcomes or doomsday prophecies: they are accounts of real events.

Take wildfires. Wallace-Wells concentrates on California, which has always been susceptible to burning. In 2017, more than nine thousand separate wildfires were recorded, including five of the twenty worst ever recorded in the state. Two thousand square miles burned. A similar area was destroyed again in 2018 by six thousand fires, among them a giant network called the ‘Mendocino Complex’, which blazed across four counties between July and September. It grew to be bigger than New York, destroying almost half a million acres of land. Wildfires now burn twice as much land per year in the US as they did fifty years ago, and that figure is expected to double again by 2050 to twenty million acres per year. ‘For every additional degree of global warming, it could quadruple.’ This isn’t just an American problem, of course: in Greenland ten times more land than usual was lost to wildfires in 2017; in 2018, Swedish forests within the Arctic Circle succumbed to fires of unprecedented size. Wildfires in Greece killed more than a hundred people during the European heatwave of 2018, the sixth highest direct death toll in the last century. A hundred thousand fires burned across the Amazon during 2017.

Like everything else that happens within a responsive and interconnected ecological system, fires contribute to cumulative processes. Soot and ash from boreal fires blacken the northern ice sheets, which then absorb more solar heat and melt faster. Denuded hillsides increase the likelihood of disasters such as flooding and landslides (thousands were evacuated and many killed in the mudslides that followed the 2017 California fires). Burning forests release vast quantities of carbon into the atmosphere. One major wildfire in California can set the emission gains of the entire state back to zero for the year, making ‘a mockery of the technocratic, meliorist approach to emissions reduction’. Recent news reports suggest that Arctic wildfires have released as much carbon dioxide in the last month as Sweden does in the course of a year.

The loss of forests to fire adds to the general disaster of worldwide deforestation, a major cause of increasing carbon emissions. It is estimated that, at current rates, tropical deforestation would produce a further 1.5°C of warming, even if emissions from fossil fuels stopped tomorrow. The loss of forest resulting from Jair Bolsonaro’s policy of opening the Amazon to ‘development’ could add 13.2 gigatons of carbon to the atmosphere before 2030, the equivalent of almost a year’s worth of Chinese and American emissions. (Given what we now know about the consequences of unabated emissions, perhaps acts of such destructive magnitude should be recognised as a special kind of international crime.)

As the unprecedented disasters, terrifying statistics and nightmare scenarios continue to mount, the links between them multiply in tangled profusion. Climate scientists refer to ‘systems crises’, Wallace-Wells to ‘cascades’: tumbling sequences of events connected within a dynamic chaos of feedback loops, amplification and reinforcement. ‘Complexity is how warming articulates its brutality,’ as Wallace-Wells puts it. Most of the known feedback mechanisms look as though they will trigger even more warming. One of the key variables complicating climate forecasts is how much more carbon we will pump into the atmosphere. On that count too, the reports are dismal. Only seven of the 195 signatories to the 2016 Paris Agreement are ‘in range’ of their carbon emissions pledges. Even if every country was to keep to its target, this could still deliver more than 3°C of warming (not given to understatement, Wallace-Wells says this would ‘unleash suffering beyond anything humans have ever experienced’). The agreed ‘must-meet target’ in 2016 was 2°C, a level which will anyway almost certainly be enough to cause the collapse of the polar ice sheets, and the attainment of which is now regarded as improbable without the massive implementation of carbon capture technology, a technology that does not exist on any meaningful scale. (Nature has dismissed global warming projections based on carbon capture and storage as ‘magical thinking’.) Some estimates suggest that to keep warming below the agreed 2°C using existing technology would require ten new carbon capture plants to open every week for seventy years. There are currently 18 plants worldwide. And since the Paris Agreement, overall emissions have risen. The World Bank predicts that there will be 140 million climate refugees by 2050; the UN thinks it might be more like 200 million, or even, in the worst-case scenario, a billion. The poorest countries, which have caused least pollution, will bear the brunt of the suffering, and already do.

‘We have already exited the state of environmental conditions that allowed the human animal to evolve in the first place,’ Wallace-Wells writes, ‘in an unsure and unplanned bet on just what that animal can endure. The climate system that raised us, and raised everything we now know as human civilisation, is now, like a parent, dead.’ He is not a climate scientist, so is perhaps less circumspect than he might be: the data here is designed to scare us. ‘I am alarmed,’ he writes. Who isn’t? We know exactly where we are, despite the continuous chatter of doubt and denial. Wallace-Wells is scathing about the oil industry, whose disinformation clogs public discourse and waylays political processes: ‘A more grotesque performance of corporate evilness is hardly imaginable, and, a generation from now, oil-backed denial will likely be seen as among the most heinous conspiracies against human health and well-being as have been perpetrated in the modern world.’

How on earth are we supposed to think about all this horror? How do we plan for the future or raise children knowing what we know? The magnitude and implications of climate change short-circuit the imagination. Wallace-Wells cites the novelist Amitav Ghosh, who has suggested that we fail to put climate change into proper perspective because we don’t yet have the stories to comprehend it. Even the refrains ‘by 2100’ or ‘by 2050’ seem more like magic charms, pushing the disaster into an infinitely receding future. Faced with a planetary-scale crisis that requires urgent collective action, contemporary minds and institutions are left embarrassingly exposed: imagining the necessary change within our political cycles, even our lifespan, appears to be an impossible leap.

What will real action look like, if and when it finally comes? Wallace-Wells reminds us that we have the tools to change things, and even – a rare moment of optimism – ‘to stop it all’. His remedy involves ‘a carbon tax and the political apparatus to aggressively phase out dirty energy; a new approach to agricultural practices and a shift away from beef and dairy in the global diet; and public investment in green energy and carbon capture.’ But whether the changes that are already underway could be stopped by such measures is presently moot: ‘We … haven’t yet discovered the political will, economic might and cultural flexibility to install and activate them.’ Depressingly, it could have been so much easier. If decarbonisation had started in 2000, only a 3 per cent annual emissions reduction would have been necessary to keep us below 2°C of warming. The figure now is 10 per cent per year. If we wait until 2030, it will be 30 per cent. The UN secretary general, António Guterres, believes there is only one year left in which to begin this reduction. The IPCC says that global mobilisation on the scale of the Second World War will be necessary.

Many people, especially the young, have seen enough; like Wallace-Wells, they demand that others, especially those with the power to act, start to respond too. The pepper-spraying of Extinction Rebellion protesters in Paris in June and the claim by the former head of British counterterrorism that the group represents ‘anarchism with a smile’ illustrate how climate-related action by the public is likely to be handled, even by ostensibly liberal governments. State security services and corporate interests long ago classified environmental groups as a threat; they will not be quick to recast them as the vanguard of planetary salvation. Reporting on the environment is second only to reporting from war zones in terms of the number of journalists killed, attacked or threatened. Talk of a ‘Green New Deal’ and similar policies still belongs to political factions and activist groups, when everything we know about climate change suggests it should be the global first order of business. It may be symbolically significant for the UK government to declare a ‘climate emergency’, but what is urgently needed are vast, co-ordinated programmes of decarbonisation. The old certainties no longer apply. We are on an alien planet.