During the rise of mammals, following the Chicxulub impact (above) that ended the dinosaur epoch with the force of 300 million nuclear bombs, the planet’s temperatures spiked in a spooky way that the planet may experience again and soon. The planet’s leading climate scientists, including the late Stephen Hawking, are predicting that Earth will soon reach a tipping point and that the human species we’ll need an escape plan, an insurance policy, a Planet B.
The most striking feature of this early age of mammals, writes Peter Brannen in The Atlantic is that “it was almost unbelievably hot, so hot that around 50 million years ago there were crocodiles, palm trees, and sand tiger sharks in the Arctic Circle. On the other side of the blue-green orb, in waters that today would surround Antarctica, sea-surface temperatures might have topped an unthinkable 86 degrees Fahrenheit, with near-tropical forests on Antarctica itself. There were perhaps even sprawling, febrile dead zones spanning the tropics, too hot even for animal or plant life of any sort.”
This past January, in a scary analysis in the journal Science, scientists reported that over the past 50 years, the volume of the ocean with no oxygen at all has quadrupled, while oxygen-deprived swaths of the open seas have expanded by the size of the Europe.
In 2017 , a research team led by the German oceanographer Sunke Schmidtko quantified for the first time that human civilization has drained 2 percent of the oxygen from the planet’s oceans since 1960.
Dramatically declining oxygen in the oceans like we see today is a prelude to many of the worst mass extinctions in Earth’s history. The most severe occurring 94 million years ago, known as Oceanic Anoxic Event 2.
“While the supersonic asteroid that would eventually incinerate dinosaurs was still silently boomeranging around the solar system, writes Brannen, “a gigantic pulse of carbon dioxide rose from the bottom of the ocean. The Earth warmed, the seas rose, and oxygen-deprived waters spread.”
“Basically the entire continental shelf went anoxic,” said Sune Nielsen, a geochemist at the Woods Hole Oceanographic Institution in Massachusetts. “There was no oxygen at the bottom of the shelf anywhere in the world.”
Over at MIT, Daniel Rothman professor of geophysics and co-director of MIT’s Lorenz Center states emphatically that our fragile blue dot is in the grips of the Sixth Mass Extinction: The best-case scenario projects that humans will add 300 gigatons of carbon to the oceans by 2100, while more than 500 gigatons will be added under the worst-case scenario, far exceeding the critical threshold. In all scenarios, says Rothman by 2100, the carbon cycle will either be close to or well beyond Earth’s threshold for catastrophe.
So, we should despair and evacuate our planet and go somewhere else. That’s a dangerous delusion says Martin Rees in his new book, “On the Future” that examines the existential threats that face humanity over the next century. From cyberattacks to advances in biotechnology to artificial intelligence to climate change, Rees, Britain’s premier astrophysicist royal, says we are living at a critical juncture — one that could define how the human species fares.
“I know it’s been promoted by Elon Musk and also by my late colleague Stephen Hawking,” says Rees, but I think there’s no Planet B. The world’s problems can’t be solved by escaping from the world. They’ve got to be tackled here.”
Although a few intrepid pioneers are going to live on Mars, observes Rees, “terraforming Mars is much, much harder than ensuring we have a sustainable situation here and avoid massive climate change.
“I think there is a likelihood that by the end of the century there will be a community of people living on Mars. I think they will be people who are thrill-seeking adventurers rather than normal people. I think they will go there, not through a NASA program, but through one of these private space endeavors, like Elon Musk’s SpaceX or Jeff Bezos’s Blue Origin. I don’t think they’ll be followed by large numbers.
“These people on Mars — I think they will be important for the far future of the 22nd century and beyond, because they will be in an environment to which they’re ill adapted. They will have every incentive to use bio-modification and maybe cyborg techniques — linking to electronic machines — to adapt to their alien environment. They will quite quickly become like a new species.”
Image credit top of page: Impact image with thanks of Barcroft Productions/BBC
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