Key takeaways

  • An asteroid strike 66 million years ago caused a massive extinction event, wiping out the dinosaurs.
  • The impact caused global wildfires, leading to two years of darkness that stopped photosynthesis.
  • The prolonged darkness led to severe environmental collapse, with 75% of Earth’s life forms going extinct.
  • Scientists presented findings at the American Geophysical Union, explaining the darkness’s impact on extinction.
  • Despite the devastation, the extinction event allowed mammals to rise, leading to the evolution of new species, including humans.

The asteroid strike that killed out the dinosaurs 66 million years ago generated two years of darkness due to the smoke from roaring wildfires that filled the sky and obscured the light.

This process exacerbated the subsequent wave of extinctions. The findings were presented at the American Geophysical Union‘s annual conference.

Environmental impact from asteroid impact

While the asteroid impact wiped out numerous living forms almost quickly, it also triggered environmental changes that resulted in mass extinctions over time.

According to research conducted by the California Academy of Sciences’ Department of Invertebrate Zoology and Geology, one such extinction trigger could have been the dense cloud of ash and other particles that spread across the planet following the asteroid impact, which enveloped many parts of the Earth in darkness for up to two years.

During that period, photosynthesis most likely ceased, resulting in severe environmental collapse, with at least 75 percent of life on Earth extinct.

“The common thinking now is that global wildfires would have been the main source of fine soot suspended into the upper atmosphere,” said research lead author Peter Roopnarine, a curator of Geology at the California Academy of Sciences.

“The concentration of soot within the first several days to weeks of the fires would have been high enough to reduce the amount of incoming sunlight to a level low enough to prevent photosynthesis.”

Periods of darkness destroy ecosystems

Roopnarine and his colleagues believe that ecosystems may recover from periods of darkness lasting up to 150 days. However, after more than 200 days, some species will start to become extinct, and dominance patterns will shift. During a darkness gap of 650 to 700 days, extinction rates can reach 65 to 81 percent.

Because it is known that around 75% of species became extinct following the asteroid impact 66 million years ago, experts assume the dark era lasted about two years.

“Conditions varied across the globe because of atmospheric flow and temperature variation, but we estimated that the darkness could have persisted in the Hell Creek area [a representative, fossil-rich region dating to the latter part of the Cretaceous and extending over parts of today’s Montana, North Dakota, South Dakota and Wyoming] for up to two years,” according to Roopnarine.

More about the asteroid that killed the dinosaurs

Around 66 million years ago, an asteroid slammed our planet with a force unprecedented in recent history, radically altering the course of life. This catastrophe, also known as the Cretaceous-Paleogene (K-Pg) extinction event, resulted in the decline and eventual extinction of around 75% of Earth’s species, most notably non-avian dinosaurs.

The fateful asteroid impact

This massive asteroid, believed to be roughly 10 kilometers (6 miles) in diameter, crashed into Earth at breakneck speed. When it collided with what is now Mexico’s Yucatán Peninsula, it formed the Chicxulub crater, a gigantic depression measuring more than 150 kilometers (93 miles) in diameter.

Immediate aftermath of the asteroid impact

The collision is predicted to have unleashed enough energy to power billions of atomic bombs. This enormous force sparked flames hundreds of kilometers distant and spewed massive amounts of sulfur into the sky, resulting in a dramatic dip in temperatures.

The Earth was thrust into a “nuclear winter” scenario: dark, cold, and unfriendly. The outpouring of dust and soot caused dropping temperatures and extensive darkness, severely disrupting the food chain. Photosynthesizing plants would be unable to thrive in such conditions, resulting in a chain reaction of extinctions further up the food chain.

Longer-term effects

But the asteroid’s collision produced more than just dust and soot. It also caused extensive acid rain, severely disrupting ecosystems. The ash from the impact blocked sunlight for a long time, cooling the earth and changing the climate for several years.

Oceans did not escape unharmed. The asteroid’s fallout had a catastrophic impact on marine ecosystems. The temperature shift caused a drop in marine plankton, which is the principal food supply for many marine organisms. The collapse of this basic stratum of the marine food chain has devastating consequences for the marine animals that relied on it.

Recovery and evolution’s new course

Despite the devastation, life remained resilient. The extinction catastrophe allowed mammals, which had previously lived in the shadows of dinosaurs, to gain prominence and diversify. These animals will later develop into a diverse group of species, including humans.

Over time, the Earth’s atmosphere and climate stabilized, allowing life to rebound and evolve in new ways. The dinosaurs’ extinction paved the way for the birth of new dominating species, changing the planet’s evolutionary destiny.

The asteroid that crashed Earth 66 million years ago drastically altered the destiny of life on our planet. While it was the end of the dinosaurs and many other species, it also created new prospects for evolution. The story of this asteroid is a stark reminder of the power of alien occurrences and their ability to change the fundamental fabric of life on Earth.

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