The last time it got this hot our cousins must have been getting very lonely. We haven’t seen temperatures like this week since the last members of Homo erectus disappeared from the Earth over 100,000 years ago. In fact, it’s been so long since temperatures were so high that there were at least four human species roaming the planet.

The last Homo erectus are thought to have disappeared from the island of Java during the Eemian interglacial period. Neanderthals and Homo floresiensis vanished during the last ice age, leaving our solitary twig on the branch of the human family tree.

Paleoclimate was a wild ride. Our direct measurements only date back to 1979 but scientists use ice cores and other proxies to reconstruct temperatures back to the Eemian and beyond.

Climate deniers are quite right that it’s been much hotter and much colder in the distant past than it is today. They tend not to mention the mass extinctions tied to carbon in the atmosphere or the fact that most of the paleoclimate was utterly inhospitable. Most of the time, we couldn’t have survived at all.

We certainly couldn’t have built civilization. If our lonely erectus cousins were gazing mournfully across the Java Sea 100,000 years ago wondering where everyone had gone, they wouldn’t have been anywhere near the beaches today — sea levels were six meters higher.

Only very recently did we catch a break. The Holocene period over the last 10,000 years has been a rare Goldilocks zone.

Credit Glen Fergus (CC BY-SA 3.0)

That Goldilocks zone answers one of the big puzzles of deep time: We sapiens haven’t been around nearly as long as Homo erectus’ successful run (they lasted an impressive two million years). But we’ve had the same brains and bodies we do today for a couple hundred millennia. And yet, we only got farming, science and ice cream in one sudden, recent burst.

The invention of the wheel, agriculture, cities, everything we call civilization, all thanks to that precious Goldilocks zone. It’s the kind of perspective that suggests an answer to Fermi’s paradox — aliens may be so hard to find because the combination of intelligence, energy and a conducive environment results in species blowing out of their Goldilocks zone before they develop enough wisdom and self-awareness to act decisively when the porridge is getting too hot.

Monday, July 3 was the hottest day we’ve ever measured. July 4 broke that record. July 5 tied it.

Thursday set a new one — a full 1.68 C above pre-industrial temperatures. Well outside the Goldilocks guardrail of 1.5 C. By the time you read this, we may well have broken the record again.

“It’s not a record to celebrate and it won’t be a record for long, with Northern Hemisphere summer still mostly ahead and El Niño developing,” said Friederike Otto from the Grantham Institute for Climate Change and the Environment in the U.K.

“It’s a death sentence for people and ecosystems.”

You’re probably all too aware of the fires across Canada. The conflagration is now literally off the charts (Natural Resources Canada had to create a new one, extending the government’s Y-axis). And it’s global. About 40 percent of the world’s oceans are suffering marine heat waves. China and Southeast Asia are roasting under prolonged record-breaking heat and the sea ice around Antarctica is falling off the charts. Africa set a particularly ominous record — a record minimum temperature — it did not fall below 39.6 C in Adrar, Algeria, even at night.

“It just shows we have to stop burning fossil fuels. Not in decades, now,” Otto told CNN.

Otto is one of many brilliant people you’ll meet in Jeff Goodell’s new book, The Heat Will Kill You First: Life and Death on a Scorched Planet. Maybe not the most welcoming title but definitely the book to read if you want to come to grips with our scorching reality.

Goodell’s book will be hitting bookstores this coming week. Almost absurd timing given the state of the world. Timing matched only by John Vaillant’s Fire Weather: The Making of a Beast, which we looked at a few newsletters ago just as smoke smothered cities across North America. Neither makes for light reading but they make good companions — both authors are marvellous storytellers, introducing us to a cast of fascinating and colourful characters, weaving science and history to leave us with a much sharper understanding of our current situation.

For Goodell, heat itself becomes a character looming behind the others. “Before there was light, there was heat. It is the origin of all things and the end of all things,” he writes.

You might know Goodell for his reporting with Rolling Stone where he coined the nickname “Doomsday Glacier” writing about Thwaites in Antarctica. You can track the evolution of his reporting from his book titles: 2017’s The Water Will Come has given way to The Heat Will Kill You First.

In his latest book, Goodell wants us to meet Otto because it turns out scientists can pinpoint the cause of heat waves more easily than many climate impacts. And, in addition to being “the kind of person who wears green Converse high-tops everywhere and who is almost as serious about modern dance as she is about modern climate,” Otto is at the forefront of attribution science.

Until recently, each extreme weather event was dutifully followed by scientists’ disclaimer that catastrophes were becoming more likely but that no specific event could ever be attributed to climate change.

That’s changed. Otto’s first published paper confirmed the role of climate change in a 2010 heat wave in Russia that killed 55,000 people. The attribution process is getting so quick, it can be done almost in real time — quickly enough to seize public attention and soon, perhaps, to determine liability and hold fossil fuel companies and their enablers accountable.

“To me, science is — or can be — a tool for justice,” Otto tells us. “Extreme event attribution is the first science ever developed with the court in mind.”

Goodell asks Otto whether she can foresee a time when a company like ExxonMobil gets held liable in court for the damage and deaths from extreme heat.

“‘Yes, I can,’ she replied without hesitation. ‘Not only can I imagine it. I believe it will happen sooner than you think.’”

The Heat brings us along on adventures to both ends of the Earth and hot spots in between. A journey across Baffin Island, hauling sleds, warding off hungry polar bears and debating solar radiation management with David Keith. We join humanitarians helping people on their desperate journeys. Planners redesigning cities built for the Goldilocks zone.

Along the way, you’ll learn a lot about the effect of heat on our own bodies and receive some hard-earned practical advice. “If there is one idea in this book that might save your life, it is this,” Goodell writes. “The human body, like all living things, is a heat machine.”

Many of the characters and stories will stick with you. But the bookends will, too. That’s where Goodell really pans back to the broader picture. The title of his epilogue? Beyond Goldilocks. Definitely a book for our time.