A meteorite killed dinosaurs. It also caused global darkness
It's commonly believed that the impact of a meteorite 66 million years ago resulted in the extinction of dinosaurs. Yet, its ramifications were much more extensive. The planet had plunged into darkness, and scientists are investigating a new theory regarding its precise influence on the Earth's climate changes.
The Chicxulub meteorite, approximately 6.2 miles in diameter, is said to have crashed into what is now known as the Yucatan peninsula about 66 million years ago. The impact unleashed an explosion that released around 100 trillion tons of TNT equivalent, propelling an enormous amount of sulfur, soot, and dust into the atmosphere, triggering global darkness. Determining which of these elements had a profound influence on the acute climate change that ensued has been an enduring question for scientists.
A study published in the renowned "Nature Geoscience" journal postulates that dust may have been the paramount destructive factor. While soot and sulfur undoubtedly contributed to the worldwide blackout and subsequent prolonged winter—almost extinguishing photosynthesis for two years—the finely pulverized granite dust, originated from the collision, dwelled in the atmosphere for up to 15 years. This dust potentially played a significant role in the mass extinction, eradicating 75 percent of all species on Earth.
Simulations of the Cretaceous period's paleoclimate revealed that the dust dispersed globally within days following the meteorite strike.
"We found out that the dust-induced disruption in photosynthetic activity is huge, much larger than what we anticipated before this research," stated Dr. Cem Berk Senel, the study's team leader and a researcher from the Royal Observatory in Belgium, during an interview with Live Science.
The asteroid collision that marked the tail end of the Cretaceous period (145–66 million years ago) resulted in a crater 111.8 miles wide and 12.4 miles deep. Material from this immense chasm promptly reached the atmosphere. Senel and his team performed tests on dust grain sizes in a 4.3-foot layer from the Tanis site in North Dakota to determine what was launched into the atmosphere due to the impact. The gathered data were then fed into a computer-simulated global atmosphere model. The simulation suggested that dust grains, approximately 0.03 to 0.31 thousandths of an inch in diameter, had spread globally within approximately a week.
Dust engulfed the entire planet
The process of photosynthesis, disrupted by the impact, took an estimated four years to return to its pre-impact intensity in plants. Scientists reckon that half the plant species were wiped out. However, seeds proved to be hardier than animals, able to remain dormant and sprout again under improved conditions.
While the atmosphere started clearing of sulfur particles after around 8.5 years, fine dust particles continued to linger for as long as 15 years.
The cumulative effect of these disturbances caused the temperature to plummet by up to 59 degrees Fahrenheit, a reduction primarily attributable to dust and sulfur, according to Senel.
Separately, Clay Tabor, a University of Connecticut-based paleoclimatologist, who was unaffiliated with the research, found the results intriguing but not irrefutable. Different studies relying on dissimilar climate models can yield varying conclusions, Tabor mentions that the differing perspectives on whether soot or dust had a more significant global impact could be attributed to the differences between the models employed.
