Did Comets Kill the Dinosaur? | The Role of Geological Cataclysms in Earth’s History

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Public Lecture Series with Mike Rampino

Global catastrophes can apparently come from above (impacts) and below (massive volcanism). The global atmospheric effects of impacts (dust clouds, soot clouds from wildfires, sulfur aerosols) can cause abrupt darkness and severe cold conditions leading to mass extinctions of life. Massive flood basalt eruptions can release large amounts of carbon dioxide (and possibly methane)—greenhouse gases that can cause a severe global warming—and halogens that can destroy Earth’s protective ozone layer, also leading to mass extinctions. The close correlation of mass extinction events in Earth’s history with times of large impacts and flood basalt eruptions supports this hypothesis.

In 1980, the scientific world was stunned when a maverick team of researchers proposed that a massive 6-mile diameter comet or asteroid strike had wiped the dinosaurs and other fauna from the Earth 66 million years ago. Scientists found evidence for this theory in a huge “crater of doom” on the Yucatan Peninsula, showing that our planet had once been a target in a galactic shooting gallery. Had it not been for that impact, mammals might have remained small furry creatures and not had the chance to evolve into all present-day mammals, including primates and homo sapiens.

The presence of Earth-crossing asteroids and comets in the solar system, and the occurrence of large impact craters on our planet mean that such impacts are a normal, recurring geologic process, which has been an important factor in biological and geological evolution on our planet.

What’s more, recent research has turned up evidence that the largest volcanic eruptions on Earth, producing lava flows covering more than a million square kilometers, can also have severe effects on climate leading to mass extinctions. The greatest mass extinction (in which 96% of species disappeared), which occurred 252 million years ago, coincides with a huge outpouring of lava in Siberia that covered an area the size of Texas. Volcanic emanations, of carbon dioxide and methane seem to have caused lethal global warming and a stagnant world ocean, as species died on land and in the seas.

Michael R. Rampino is Professor of Biology and Environmental Studies at New York University and is also a research consultant at NASA’s Goddard Institute for Space Studies in New York City. His research has been concentrated in several areas including: studies of climate change on various timescales; the products and dynamics of volcanic eruptions and their effects on the global environment; and the relationship of large asteroid and comet impacts, and massive flood-basalt volcanism, with mass extinctions of life. He has done fieldwork on six continents. His most recent work has sought a connection between geologic events and astronomical processes, including encounters of Earth with dark matter in the Galaxy. Rampino’s interest in Astrobiology is evidenced by the text, “Origins of Life in the Universe”, co-authored with Robert Jastrow (Cambridge University Press, 2008), and a new book, “Cataclysms: A New Geology for the 21st Century” (Columbia University Press, 2017).

Time: 6pm Reception, 7pm Lecture