What Wiped Out the Dinosaurs? Part 2: The Effects
In last Monday’s article, I discussed the conclusions drawn by a panel of 41 scientists from their careful review of over twenty years’ worth of research findings concerning the cause of the Cretaceous-Paleogene (K-Pg) mass extinction event.1 They determined beyond any reasonable shadow of doubt that a huge asteroid colliding in the Yucatán Peninsula of Mexico 65.5 million years was indeed the culprit behind the demise of the last remaining ecosystem of dinosaurs and, along with it, over half of all other species. In the second and last part of the series I will describe the panel’s conclusions concerning the effects brought about by the collider and what those effects imply for the creation/evolution debate.
Taking advantage of the latest measurements of the crater size and the ejecta deposits, and using updated models for the dynamics of the asteroid-Earth collision event, the team calculated the physical and chemical effects of the collision event. Hitting as it did on the Atlantic seashore, the collider generated megatsunamis reaching up to several hundred feet high.2 The impact induced earthquakes exceeding magnitude 11 (more than 10,000 times the magnitude of the recent quake in Haiti).3 The collision event ejected and distributed around the globe the especially sulfate-rich sediments that existed at the collision site. Very conservatively, at least 100 to 500 billion metric tons of sulfur were released into the terrestrial atmosphere within minutes after the impact.4 This sulfur, rapidly transforming into sulfur aerosols, cooled Earth’s surface by up to 10° centigrade (18° Fahrenheit) and kept it that way for many years, even several decades. It generated global acid rains, which ,along with soot and dust, led to severe respiratory distress for all large-bodied land-dwelling animals. “Instantaneous (days to months) destruction of diverse forest communities coincident with deposition of ejecta from the Chicxulub impact” occurred.5 To quote from a previous study on the consequences of a large asteroid collision, “The combination of all these physical effects would surely represent a devastating stress on the global biosphere.”6 The stress was all the more devastating given that Earth’s life had already been traumatized by the 1.5 million years of on and off super-volcanic eruptions occurring on the Deccan plateau just prior to the collision event.
Darkness, pervasive cold, and suffocating dust and aerosols suppressed photosynthesis, thus bringing about plant and animal extinction. Creatures (like the dinosaurs and animals relying on plankton) dependent on primary producers disappeared. But detritivores (creatures feeding on dead organisms) flourished.
This compression of nearly all the K-Pg extinctions into one near instantaneous, globally pervasive event poses a challenge to non-theistic models for the history of life. It’s difficult enough for Darwinian evolution to explain the appearance of new sets of species from several relatively minor, time- and geographically-separated extinction events. It is far more challenging to explain the appearance of new species from a single mass extinction disaster of such catastrophic proportions as the Chicxulub collision event.
Explaining the rapidity with which mass speciation events followed the K-Pg mass extinction presents another challenge for non-theistic models. Darwinian evolutionary mechanisms are inherently slow and inefficient. Yet in some cases dramatic mass speciation events are measured to have taken place within just thousands of years or less after the K-Pg mass extinction event.7
Furthermore, the growing recognition that giant asteroid/comet collision events on Earth over life’s history cannot be rare also creates problems for non-theistic models. Over the past several decades, geologists have discovered evidence for many ancient impact craters measuring in excess of 100 kilometers (62 miles) in diameter. Astronomers have confirmed that two much larger belts—the Kuiper belt and the Oort cloud—complement the main asteroid belt in our solar system. They also have discovered even bigger belts of asteroids and comets orbiting nearby stars.8 Additionally, as the Sun orbits about the center of the Milky Way Galaxy, close stellar encounters disturb the dynamics of the solar system’s three belts of asteroids and comets. Thus, several large impact collision events on Earth throughout life’s history were inevitable.
It now appears that the solar system is relatively deficient in asteroids and comets. The deficiency level, however, reveals fine-tuning. In fact, some astronomers argue that the quantity, size, and placement of asteroids and comets should be incorporated into the anthropic principle, which states that the universe, Milky Way Galaxy, and solar system manifest many fine-tuned properties that make the existence of life and humans in particular possible. They point out9 that if Earth receives too few asteroid/comet collision events, the planet surface would lack sufficient amounts of the volatiles, refractories, and metals that advanced life requires. On the other hand, too many asteroid/comet collision events would be hazardous to advanced life.
Another manifestation of the fine-tuning design of the rate and intensity of asteroid/comet collision events concerns the faint Sun paradox.10 As the Sun’s nuclear furnace fuses hydrogen into helium, its core density increases. This increase causes more efficient nuclear fusion, which makes the Sun shine with increasing brightness. Today, the Sun is about 15 percent brighter than it was 3 billion years ago. But a particular ecology of life pulls the just-right quantities of greenhouse gases from Earth’s atmosphere to keep the planet’s surface at the ideal temperature for life.
Mass extinction and mass speciation events must be carefully designed and timed. Anything less fine-tuned would have left Earth with the wrong life at the wrong time and places to make the necessary adjustments to Earth’s atmosphere, continents, and oceans to compensate for the changing physics of our planet, galaxy, Sun, and Moon. For the same reason life’s history on Earth cannot be a mindless process. Someone must be exercising a guiding hand to ensure that biology does not get out of sync with astronomy, physics, geology, and chemistry. The marvel of life on Earth is that it has lasted as long as 3.8 billion years and for virtually all of that long epoch has existed at an extremely high level of abundance and diversity.
|Part 1 | Part 2|
- Peter Schulte et al., “The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary,” Science 327 (March 5, 2010): 1214–18.
- Owen B. Toon et al., “Environmental Perturbations Caused by the Impacts of Asteroids and Comets,” Reviews of Geophysics 35 (January 1997): 41–78.
- B. A. Ivanov, “Numerical Modeling of the Largest Terrestrial Meteorite Craters,” Solar System Research 39 (September 2005): 381–409.
- Schulte et al., 1217.
- Peter Schulte et al., 1218.
- Owen B. Toon et al., 41.
- Julio Sepúlveda et al., “Rapid Resurgence of Marine Productivity after the Cretaceous-Paleogene Mass Extinction,” Science 326 (October 2, 2009): 129–32; Paul Bown, “Selective Calcareous Nannoplankton Survivorship at the Cretaceous-Tertiary Boundary,” Geology 33 (August 2005): 653–56; Vivi Vajda, J. Ian Raine, and Christopher J. Hollis, “Indication of Global Deforestation at the Cretaceous-Tertiary Boundary by New Zealand Fern Spike,” Science 294 (November 23, 2001): 1700–2; R. D. Norris, B. T. Huber, and J. Self-Trail, “Synchroneity of the K-T Oceanic Mass Extinction and Meteorite Impact: Blake Nose, Western North Atlantic,” Geology 27 (May 1999): 419–22; Kenneth G. MacLeod et al., “Impact and Extinction in Remarkably Complete Cretaceous-Tertiary Boundary Sections from Demerara Rise, Tropical Western North Atlantic,” Geological Society of America Bulletin 119 (January/February 2007): 101–15; Richard K. Olsson et al., “Ejecta Layer at the Cretaceous-Tertiary Boundary, Bass River, New Jersey (Ocean Drilling Program Leg 174AX),” Geology 25 (August 1997): 759–62; Richard A. Kerr, “Cores Document Ancient Catastrophe,” Science 275 (February 28, 1 997): 1265.
- Paul Kalas et al., “First Scattered Light Images of Debris Disks around HD 53143 and HD 139664,” Astrophysical Journal Letters 637 (January 20, 2006): L57–L60.
- Nathan Kaib, “The Effects of Oort Cloud Comet Showers on Earth,” Astrobiology 8 (April 2008): 341.
- Hugh Ross, More Than a Theory (Grand Rapids: Baker, 2009), 153–62.