Six Degrees
by Mark Lynas
Summary
Lynas's design is the simplest and most effective in climate writing: one chapter per degree. Take the range of warming the models offered for this century, one to six degrees Celsius, and walk through it floor by floor, asking at each landing what the peer reviewed literature actually says the world looks like there.
One degree is the world already arriving as he wrote: shifted seasons, strengthening drought in the subtropics, the first ecosystems in visible trouble. Two degrees brings the heatwaves that kill by the tens of thousands, acidifying oceans, and the likely end of the coral reefs. Three degrees is where the book's temperature rises with its subject: the Amazon at risk of burning into savanna, agriculture retreating from whole regions, and the first of the feedbacks, carbon cycle and permafrost, that begin to add warming no policy controls. Four and five degrees empty the subtropics and rewrite coastlines; six returns the planet to conditions last seen in the deep past, with the fossil record's own mass extinctions offered as the closest analogues. The feedback chapters are the scientific heart: methane hydrates, dieback and albedo, the mechanisms by which one floor's warming buys a ticket to the next.
The method's honesty is the point: every claim is cited to the primary literature, assembled rather than asserted, and Lynas is scrupulous about probability, each floor described as the mapped risk at that temperature rather than a certainty.
Around three hundred and fifty pages.
Best for readers who want climate change translated from abstraction into consequences with addresses, one degree at a time.
Historical Context & Significance
Six Degrees won the Royal Society prize in 2008, the first climate book to take the award, and National Geographic built a documentary, Six Degrees Could Change the World, on its scaffold. The degree by degree frame proved among the most contagious devices in science communication, reused in policy documents and journalism ever since precisely because it converts a scenario range into a story.
Mark Lynas came to the subject as an activist turned author, and his later trajectory became a story in itself: The God Species and his public recantation on genetically modified crops made him one of the environmental movement's most prominent heretics, arguing nuclear power and biotech into the green toolkit.
The science moved, so the book did too: Our Final Warning, his full 2020 rewrite, redid every chapter against a decade of new literature, finding the lower floors closer and the upper ones better mapped. That the original needed updating rather than retracting is its vindication.