Monday, January 16, 2017

Darkness and coldness - killed the dinosaurs

Artist depiction on the impact of the asteroid 

Sixty six years ago, the extinction of the dinosaurs gives the evolution of the mammals, which results to the human being on earth. The scientist discovered because of the impact of the asteroid, the droplets of sulfuric acid formed in the atmosphere as clouds. These clouds blocked the sunlight for several years. Due to this the plants died and the death spreads through the food web. The previous theories were based on the dust evolved by the impact. But the new theory show that the sulfuric droplets resulted in long-lasting cooling which brings the end to the dinosaurs.

"The big chill following the impact of the asteroid that formed the Chicxulub crater in Mexico is a turning point in Earth history," says Julia Brugger from the Potsdam Institute for Climate Impact Research (PIK). She is the lead author of the study to be published in the Geophysical Research Letters. She also says "We can now contribute new insights for understanding the much debated ultimate cause for the demise of the dinosaur at the end of the Cretaceous era." To prove this theory the scientists used a special computer process using a climate model on the atmosphere, ocean and the sea ice. The researchers did research proving that the sulfur vaporized from the asteroid is the main reason for blocking the sunlight and cooling down the earth.    

In the tropical region, the annual mean temperature reduces from 27 - 5 degree Celsius. "It became cold, I mean, really cold," says Brugger. The temperature of the global annual mean surface drops down by at least 26 degrees Celsius. The dinosaurs used to live in flourishing climate. After the asteroids impact the average annual temperature was below the freezing point for above 3 years. Because of this the ice caps expanded. Even on the tropical region the temperature eventually went down from 27 degree to hardly 5 degree Celsius. "The long-term cooling caused by the sulfate aerosols was much more important for the mass extinction than the dust that stays in the atmosphere for only relatively short time. It was also more important than local events like the extreme heat close to the impact, wildfires or tsunamis," says the co-author Georg Feulner who who leads the research team at PIK. The scientists also discovered that it took 30 years for the climate to recover. 

Through the study of the earths past the scientist can predict the future threats by asteroids to the earth. "It is fascinating to see how evolution is partly driven by an accident like an asteroid's impact -- mass extinctions show that life on earth is vulnerable," said Feulner. "It also shows how important the climate is for all species on our planet. Now-a-days the most immediate threat is not from natural cooling but from human-made global warming" 


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