Scientific debates have long focused on whether massive volcanic eruptions on the Indian subcontinent played a significant role in the extinction of dinosaurs or whether the Chicxulub meteorite was the sole cause. These eruptions, occurring approximately 30,000 years before the meteorite impact, released vast amounts of CO2, sulfur, and dust into the atmosphere, leading to significant climate changes. However, recent research reveals that these climatic effects had dissipated long before the mass extinction event.
Climate scientists from Utrecht University and the University of Manchester analyzed fossil molecules in ancient peats from the United States to reconstruct air temperatures during this period. Their findings demonstrate that volcanic activity caused a temporary cooling of about 5°C, but temperatures had already stabilized and warmed to pre-eruption levels approximately 20,000 years before the meteorite impact. This warming was likely driven by volcanic CO2 emissions.
The Chicxulub meteorite impact, in contrast, unleashed catastrophic events, including wildfires, earthquakes, tsunamis, and an “impact winter” that blocked sunlight, devastating ecosystems worldwide. These effects had far more profound and immediate consequences for life on Earth, ultimately leading to the extinction of the dinosaurs.
By analyzing the structure of temperature-sensitive molecules preserved in ancient sediments, the researchers created a detailed timeline of climatic changes leading up to the extinction event. Their results confirm that the meteorite, rather than volcanic eruptions, delivered the fatal blow to the dinosaurs.
These findings not only resolve a long-standing scientific debate but also highlight the meteorite impact’s unique role in Earth’s history. The team plans to apply this methodology to other critical periods to further understand climate changes over geological time.