An artist’s rendition of 1994, as an illustration of the Chicxulub asteroid impact that killed off most of the dinosaurs about 66 million years ago.
(Donald E. Davis/NASA/JPL)
The carbon dioxide released in the atmosphere after the impact of the Chicxulub asteroid that ended the age of the dinosaurs 65 million years ago warmed the Earth’s climate for 100,000 years, a new study has revealed.
The study, based on an analysis of fossil records, suggested that the Earth’s global temperature increased by 5 degrees Celsius (9 degrees Fahrenheit) at that time.
The results raise concerns about how long it will take for the planet to recover from the effects of human-caused emissions of greenhouse gases, said Kenneth MacLeod, a professor in geological sciences at the University of Missouri and lead author of the new work, published today (24 May) in the journal Science. [How the Dino-Killing Chicxulub Asteroid Impact Was Found]
Scientists have long theorized that after the piece of space rock with a diameter of 6 to 9 miles (7 to 14 km) are captured in the Yucatan Peninsula in the vicinity of the present town of Chicxulub in Mexico, the temperature of the planet first increased strongly for minutes or hours, MacLeod said. After that, it crashed for months to decades, because the enormous amount of dust and soot thrown into the atmosphere by the impact blocked the sun’s rays. Eventually, however, the carbon dioxide released during the impact led to global warming.
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How the Dino-Killing Chicxulub Asteroid Impact Was Found
MacLeod’s study is the first empirical evidence of how long this greenhouse gas-related warming of the earth lasted and how substantial it was.
“We thought we could resolve this question by looking at the fossilized pieces of fish teeth, scales and bones of the El Kef section in Tunisia,” said MacLeod Space.com referring to a paleontological site in the northwest of Tunisia is known to be one of the world’s best-preserved fossil records from the period before and after the Chicxulub impact
“This place is known for having a beautiful plate over the interval that we look at the so-called Cretaceous-Paleogene boundary mass extinction event that occurred after the Chicxulub impact.”
The researchers looked at the concentrations of the different oxygen isotopes in the fossils. These isotopes differ in the number of neutrons in the oxygen atom and, according to MacLeod, behave slightly differently from each other.
“One of the differences is, as the temperature increases, the amount of the light isotope of oxygen, oxygen 16, in a mineral increases relatively,” MacLeod said.
“We are measuring the ratio of oxygen 16 to oxygen-18. Each 1 part per 1,000, that the ratio changes in relation to an approximately 4.5 – to 5-degree C, and 8.1 to 9 degrees F] change in temperature.”
The researchers analyzed 40 samples taken from the site in Tunisia: of 10 samples from the 50,000 years before the impact, 20 samples of the 100,000 years immediately after the impact, and the additional 10 samples from the next 200,0000 years.
“We found that there is a very large difference in oxygen isotopes between these three sets of samples — clear,” said MacLeod.
He said that he and his team now want to look at fossil samples from other parts of the world and check for similar patterns.
“It is one thing to find 5 degrees [C, 9 ° F] of the warming in North Africa. It’s even more impressive to find 5 degrees warming in North Africa, and perhaps 10 degrees [C, 18 ° F] of warming of the earth off the coast of Australia,” he said. “That would really be a reinforcement of the idea that it is a worldwide signal and a greenhouse gas-related change.”
The study, MacLeod said, not only sheds more light on what happened to the Earth of the systems after the devastating collision, but it also raises questions about the consequences of current human activities.
“If I were to draw a line under the lessons of this study for the modern time, it would be to consider the idea that what we do in our lives will have an impact on the Earth for the next 100,000 years, which is quite daunting,” MacLeod said.
Original article on Space.com.