The day the earth was shot, and almost died

The New Yorker's April 8, 2019 issue includes a feature on a paleontologist, Robert DePalma, who has been digging up some amazing artifacts which, if they're as real and as important as DePalma alleges, will significantly deepen our understanding of an event that surely was among the most catastrophic in the history of earth: the day an asteroid slammed into our planet and ended the Age of Reptiles.

Here is how Preston describes the day of the asteroid:

The energy released was more than that of a billion Hiroshima bombs, but the blast looked nothing like a nuclear explosion, with its signature mushroom cloud. Instead, the initial blowout formed a “rooster tail,” a gigantic jet of molten material, which exited the atmosphere, some of it fanning out over North America. Much of the material was several times hotter than the surface of the sun, and it set fire to everything within a thousand miles. In addition, an inverted cone of liquefied, superheated rock rose, spread outward as countless red-hot blobs of glass, called tektites, and blanketed the Western Hemisphere. 

Some of the ejecta escaped Earth’s gravitational pull and went into irregular orbits around the sun. Over millions of years, bits of it found their way to other planets and moons in the solar system. Mars was eventually strewn with the debris—just as pieces of Mars, knocked aloft by ancient asteroid impacts, have been found on Earth. A 2013 study in the journal Astrobiology estimated that tens of thousands of pounds of impact rubble may have landed on Titan, a moon of Saturn, and on Europa and Callisto, which orbit Jupiter—three satellites that scientists believe may have promising habitats for life. Mathematical models indicate that at least some of this vagabond debris still harbored living microbes. The asteroid may have sown life throughout the solar system, even as it ravaged life on Earth.

And that wasn't all:

The damage had only begun. Scientists still debate many of the details, which are derived from the computer models, and from field studies of the debris layer, knowledge of extinction rates, fossils and microfossils, and many other clues. But the over-all view is consistently grim. The dust and soot from the impact and the conflagrations prevented all sunlight from reaching the planet’s surface for months. Photosynthesis all but stopped, killing most of the plant life, extinguishing the phytoplankton in the oceans, and causing the amount of oxygen in the atmosphere to plummet. After the fires died down, Earth plunged into a period of cold, perhaps even a deep freeze. Earth’s two essential food chains, in the sea and on land, collapsed. About seventy-five per cent of all species went extinct. More than 99.9999 per cent of all living organisms on Earth died, and the carbon cycle came to a halt. 

Earth itself became toxic. When the asteroid struck, it vaporized layers of limestone, releasing into the atmosphere a trillion tons of carbon dioxide, ten billion tons of methane, and a billion tons of carbon monoxide; all three are powerful greenhouse gases. The impact also vaporized anhydrite rock, which blasted ten trillion tons of sulfur compounds aloft. The sulfur combined with water to form sulfuric acid, which then fell as an acid rain that may have been potent enough to strip the leaves from any surviving plants and to leach the nutrients from the soil.

There is lots more, especially about DePalma, who is enthusiastic but subsisting somewhere on the margins of the paleontology establishment, in his mid-30s without having finished his PhD but seemingly on the verge of rewriting the received wisdom in his field.

The debris and ash from that unimaginable disaster forms a solid line, called the KT boundary, in the layers of sediment analyzed by geologists and paleontologists who measure our history in the millions of years.  The KT boundary divides Then from Now: the age of the dinosaurs from the age of mammals which we tell ourselves that we rule today.

Until I read Preston's article, the notion of the KT boundary had never really captured my imagination.  It's a kind of Noah's Ark story, only with fire rather than water.  God, if we wish to introduce him as a character in this drama, took the Etcha-Sketch of earth up to that point and gave it a big shake.  He erased virtually everything alive (although, if DePalma is shooting it straight, he may not have wiped out as much life as previously thought).  What was left in the wake of the meteor?

The world that emerged after the impact was a much simpler place. When sunlight finally broke through the haze, it illuminated a hellish landscape. The oceans were empty. The land was covered with drifting ash. The forests were charred stumps. The cold gave way to extreme heat as a greenhouse effect kicked in. Life mostly consisted of mats of algae and growths of fungus: for years after the impact, the Earth was covered with little other than ferns. Furtive, ratlike mammals lived in the gloomy understory.

When we tell the story of evolution to explain how it is that we are who we are at this particular moment, our story needs to account for the KT boundary.  However many eons of evolution led to duckbills and ceratops and raptors, the asteroid pressed the reset button that day, and evolution essentially started from scratch.

For the first hundred million years of their existence, before the asteroid struck, mammals scurried about the feet of the dinosaurs, amounting to little. “But when the dinosaurs were gone it freed them,” DePalma said. In the next epoch, mammals underwent an explosion of adaptive radiation, evolving into a dazzling variety of forms, from tiny bats to gigantic titanotheres, from horses to whales, from fearsome creodonts to large-brained primates with hands that could grasp and minds that could see through time. 

As the vast sweep of millenia of millenia unfolded, punctuated by this calamitous event and then more millenia of millenia, the Divinity whose Name, out of respect for his people, we don't pronounce, sent his Son at a particular time and in a particular place.  He lived and was killed by the authorities.  And then he rose from the dead, freeing us from death and providing us a path to what we were meant to be.

It seems we're here today because life has been given a second chance: if evolutionists are right, there is a line of descent from mammals such as the weasel-like marsupial whose skeleton De Palma has unearthed, to us.  Had the asteroid passed by our planet that day, things probably would have evolved in a significantly different direction.

It could all end again.  We could keep heating the oceans and polluting the air and consuming all the planet's resources.  Or we could bomb one another until the earth is no longer inhabitable.  Or another asteroid could slam into the ocean.  Lord Jesus, save us from our stupidity.  Help us to get to know you.

Just something I'm pondering this Lent.