For decades, scientists have debated the events that led to the mass extinction of dinosaurs 66 million years ago. The Chicxulub meteorite impact in the Gulf of Mexico has been widely accepted as the primary cause. Massive volcanic eruptions on the Indian peninsula—known as the Deccan Traps—are also considered potential contributors. These eruptions released enormous amounts of carbon dioxide (CO2), sulphur, and dust, altering the Earth’s climate. Now, a new study by researchers from Utrecht University and the University of Manchester provides compelling evidence. Their findings show that the meteorite impact, not volcanism, was the primary driver of the extinction event.
The volcanic activity from around 30,000 years before the meteorite impact led to a significant cooling of the Earth’s climate. This cooling was temporary. According to the study, sulphur emissions from the eruptions blocked sunlight, leading to a temperature drop of at least 5°C. The resulting environmental changes would not have been enough to cause the dinosaurs’ extinction alone.
By 20,000 years before the meteorite struck, global temperatures had stabilized. They even returned to pre-eruption levels. This change was likely due to the warming effects of volcanic CO2 emissions. Lauren O’Connor of Utrecht University explains, “These volcanic eruptions had drastic consequences for life. Yet, their timing suggests they played only a minor role in the extinction of the dinosaurs.”
FOSSIL PEATS REVEAL CLIMATE TIMELINE
The study’s breakthrough came from analyzing fossil molecules in ancient peats found in the United States. These molecules, produced by bacteria, change their structure based on environmental temperatures. By studying these molecular changes, scientists reconstructed a detailed climate timeline leading up to the dinosaur extinction event.
The findings revealed that the climatic effects of the Deccan Traps eruptions had dissipated well before the meteorite impact. This rules out volcanism as a significant factor in the extinction.
CHICXULUB METEORITE: THE ULTIMATE CATASTROPHE
In contrast to the volcanic eruptions, the Chicxulub meteorite impact unleashed a cascade of catastrophic events. The asteroid caused wildfires, tsunamis, earthquakes, and an “impact winter” that blocked sunlight for months. This devastated ecosystems and halting photosynthesis, which devastated the dinosaurs.
Rhodri Jerrett of the University of Manchester emphasizes, “The asteroid triggered a chain of disasters. These disasters ultimately delivered the fatal blow to the dinosaurs.”
IMPLICATIONS FOR UNDERSTANDING EARTH’S HISTORY
The findings underscore the importance of precise climate reconstructions in understanding extinction events. The researchers come from institutions like Utrecht University, Plymouth University, and the Denver Museum of Nature & Science. They are extending these methods to other critical periods in Earth’s history. They aim to study why species, beyond just dinosaurs, went extinct.
Scientists analyze the molecular composition of ancient sediments. They aim to unlock more secrets about how Earth’s climate has shaped life. These analyses include extinction events over millions of years. This helps us understand more about dinosaurs and other ancient creatures.
