Bill McKibben has written as review of Our Final Warning: Six Degrees of Climate Emergency by Mark Lynas for the New York Review of Books. The review is devastatingly grim. Even though the world agreed to try to limit temperature increases to 1.5 degrees Celsius in the Paris Accords, it is clear that that objective will not be reached. Many states have not taken necessary steps and some, like the US, have pulled out of the agreement completely. McKibben quotes Lynas:
“If we stay on the current business-as-usual trajectory, we could see two degrees as soon as the early 2030s, three degrees around mid-century, and four degrees by 2075 or so. If we’re unlucky with positive feedbacks…from thawing permafrost in the Arctic or collapsing tropical rainforests, then we could be in for five or even six degrees by century’s end.”
McKibben continues:
“As we head past two degrees and into the realm of three, ‘we will stress our civilization towards the point of collapse.’ A three-degree rise in temperature takes us to a level of global heat no human has ever experienced—you have to wind time back at least to the Pleistocene, three million years ago, before the Ice Ages. In his last volume, Lynas said scientists thought the onset of the collapse of the West Antarctic ice sheet would take place at four degrees; now, as we’ve seen above, it seems a deadly concern at two, and a certainty at three. Higher sea levels mean that storm surges like those that marked Superstorm Sandy in 2012 could be expected, on average, three times a year. The record-setting heatwaves of 2019 ‘will be considered an unusually cool summer in the three-degree world’; over a billion people would live in zones of the planet ‘where it becomes impossible to safely work outside artificially cooled environments, even in the shade.’ The Amazon dies back, permafrost collapses. Change feeds on itself: at three degrees the albedo, or reflectivity, of the planet is grossly altered, with white ice that bounces sunshine back out to space replaced by blue ocean or brown land that absorbs those rays, amplifying the process.
“And then comes four degrees:
“Humans as a species are not facing extinction—not yet anyway. But advanced industrial civilisation, with its constantly increasing levels of material consumption, energy use and living standards—the system that we call modernity…is tottering.
“In places like Texas, Oklahoma, Missouri, and Arkansas, peak temperatures each year will be hotter than the 120s one now finds in Death Valley, and three quarters of the globe’s population will be ‘exposed to deadly heat more than 20 days per year.’ In New York, the number will be fifty days; in Jakarta, 365. A ‘belt of uninhabitability’ will run through the Middle East, most of India, Pakistan, Bangladesh, and eastern China; expanding deserts will consume whole countries ‘from Iraq to Botswana.’
“Depending on the study, the risk of ‘very large fires’ in the western US rises between 100 and 600 percent; the risk of flooding in India rises twenty-fold. Right now the risk that the biggest grain-growing regions will have simultaneous crop failures due to drought is ‘virtually zero,’ but at four degrees ‘this probability rises to 86%.’ Vast ‘marine heatwaves’ will scour the oceans: ‘One study projects that in a four-degree world sea temperatures will be above the thermal tolerance threshold of 100% of species in many tropical marine ecoregions.’ The extinctions on land and sea will certainly be the worst since the end of the Cretaceous, 65 million years ago, when an asteroid helped bring the age of the dinosaurs to an end. ‘The difference,’ Lynas notes, ‘is that this time the ‘meteor’ was visible decades in advance, but we simply turned away as it loomed ever larger in the sky.’
“I’m not going to bother much with Lynas’s descriptions of what happens at five degrees or six. It’s not that they’re not plausible—they are, especially if humanity never gets its act together and shifts course. It’s that they’re pornographic. If we get anywhere near these levels, the living will truly envy the dead….”
The wildfires in California today are just one example of how climate change is already occurring. It will also affect our supplies of water and large parts of the Arctic north. Future generations will wonder why the world remained so passive in the face of this crisis.
California wildfire smoke seen from space
World Politics News 
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