12Nov2017

Dinosaur-Killing Asteroid Cooled Earth More Than Thought

Dino

The Chicxulub impact occurred 66 million years ago when an asteroid approximately 12 kilometers (7 miles) wide slammed into Earth.

This story continues to fascinate. The Chicxulub asteroid impact that wiped out the dinosaurs likely released far more climate-altering sulfur gas into the atmosphere than originally thought, according to new research.

A new study makes a more refined estimate of how much sulfur and carbon dioxide gas were ejected into Earth’s atmosphere from vaporized rocks immediately after the Chicxulub event. The study’s authors estimate more than three times as much sulfur may have entered the air compared to what previous models assumed, implying the ensuing period of cool weather may have been colder than previously thought.

The new study lends support to the hypothesis that the impact played a significant role in the Cretaceous-Paleogene extinction event that eradicated nearly three-quarters of Earth’s plant and animal species, according to Joanna Morgan, a geophysicist at Imperial College London in the United Kingdom and co-author of the new study published in Geophysical Research Letters, a journal of the American Geophysical Union.

“Many climate models can’t currently capture all of the consequences of the Chicxulub impact due to uncertainty in how much gas was initially released,” Morgan said. “We wanted to revisit this significant event and refine our collision model to better capture its immediate effects on the atmosphere.”

https://news.agu.org/files/2015/12/Chicxulub_impact_-_artist_impression.jpg

An artist’s rendering of the Chicxulub asteroid impact that killed off most of the dinosaurs from 1994. Credit: Donald E. Davis/NASA/JPL.

The new findings could ultimately help scientists better understand how Earth’s climate radically changed in the aftermath of the asteroid collision, according to Georg Feulner, a climate scientist at the Potsdam Institute for Climate Impact Research in Potsdam, Germany who was not involved with the new research. The research could help give new insights into how Earth’s climate and ecosystem can significantly change due to impact events, he said.

“The key finding of the study is that they get a larger amount of sulfur and a smaller amount of carbon dioxide ejected than in other studies,” he said. “These improved estimates have big implications for the climactic consequences of the impact, which could have been even more dramatic than what previous studies have found.”

A titanic collision 

The Chicxulub impact occurred 66 million years ago when an asteroid approximately 12 kilometers (7 miles) wide slammed into Earth. The collision took place near what is now the Yucatán peninsula in the Gulf of Mexico. The asteroid is often cited as a potential cause of the Cretaceous-Paleogene extinction event, a mass extinction that erased up to 75 percent of all plant and animal species, including the dinosaurs.

The asteroid collision had global consequences because it threw massive amounts of dust, sulfur and carbon dioxide into the atmosphere. The dust and sulfur formed a cloud that reflected sunlight and dramatically reduced Earth’s temperature. Based on earlier estimates of the amount of sulfur and carbon dioxide released by the impact, a recent study published in Geophysical Research Letters showed Earth’s average surface air temperature may have dropped by as much as 26 degrees Celsius (47 degrees Fahrenheit) and that sub-freezing temperatures persisted for at least three years after the impact.

In the new research, the authors used a computer code that simulates the pressure of the shock waves created by the impact to estimate the amounts of gases released in different impact scenarios. They changed variables such as the angle of the impact and the composition of the vaporized rocks to reduce the uncertainty of their calculations.

A simulation of the crater and impact plume formed eight seconds after the Chicxulub impact at 45 degrees. Chart A shows the density of different materials created in the impact. The colors show the atmosphere (blue), sediment (yellow), asteroid (gray) and basement (red), with darker colors reflecting higher densities. SW is the shock wave formed by the impact. Chart B shows the temperature in Kelvin at different locations in the impact.
Credit: Pierazzo and Artemieva (2012).

The new results show the impact likely released approximately 325 gigatons of sulfur and 425 gigatons of carbon dioxide into the atmosphere, more than 10 times global human emissions of carbon dioxide in 2014. In contrast, the previous study in Geophysical Research Letters that modeled Earth’s climate after the collision had assumed 100 gigatons of sulfur and 1,400 gigatons of carbon dioxide were ejected as a result of the impact. Source: AGU

Read previous post:
Hole
How A Black Hole Lights Up Its Surroundings

How do the supermassive black holes that live at the...

Elon
Space Has Attracted Over $2 Billion This Year

Money is pouring into space.  According to a report on...

conjunction
Venus Jupiter Conjunction 2017 – Where To Look

In the early hours of Monday and Tuesday morning  (13th...

Close