Researchers from the University of Oslo in Norway have presented evidence that dinosaurs endured several volcanic winters well before the asteroid impact. Their findings appear in the journal Science Developments, reflecting a broader view of the late Cretaceous environmental stressors and how they shaped life on Earth over long stretches of time.
About 66 million years ago a planetary catastrophe unfolded, leading to the extinction of roughly three-quarters of animal species. The immediate trigger is widely recognized as a colossal asteroid strike, but volcanic activity also played a substantial and potentially compounding role. The eruption of vast amounts of volcanic gases surged into the atmosphere, altering climate patterns and contributing to the environmental crisis of the era.
Some researchers have argued that the demise of the dinosaurs was driven primarily by volcanic activity rather than the meteorite alone. Others maintain that the asteroid was the decisive blow. In an effort to clarify the role of volcanism, the Oslo team analyzed lava samples from the Deccan formations, dating to both the lower Cretaceous–Paleogene boundary, which lies before the asteroid impact, and the upper boundary, after the impact. Their work aimed to distinguish preimpact volcanic signals from postimpact effects and to map how volcanic activity overlapped with other dramatic events on the timeline.
The study’s conclusions indicate that repeated, intense emissions of sulfur and other volcanic gases could have triggered a sequence of short, planetwide volcanic winters roughly 300,000 to 400,000 years before the asteroid struck. The cooling was not uniform across regions, and while these winters disrupted ecosystems and altered habitats, they did not, on their own, erase the entire dinosaur lineage. The researchers emphasize that climate stress from volcanism would have compounded the already fragile balance of life at the end of the Cretaceous, shaping the trajectory of extinction in a complex, regionally variable way.
Another noteworthy line of thought in paleoclimatology notes that dinosaurs developed remarkable diversity and longevity before this terminal event. A long-nosed dinosaur cited in some syntheses highlights the varied anatomical strategies that once populated Earth, illustrating the richness of life that faced abrupt, climate-driven challenges. The new findings from Oslo add a crucial piece to the puzzle by showing how volcanic forcing could have prepared ecosystems for the asteroid catastrophe, influencing which species survived and which did not as global conditions shifted. The overall narrative suggests a multifactorial extinction process where volcanic winters set the stage for a final, asteroid-driven collapse, rather than a single, decisive cause.