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Volcanic winters weakened the dinosaurs before the asteroid hit

A recent study by a team of researchers from Italy, Norway, Canada, and the US suggests that before their eventual extinction, dinosaurs might have faced repeated “volcanic winters” that left them in a weakened state. 

These findings come from an analysis of sulfur and fluorine gasses trapped in ancient volcanic rocks from the Deccan Traps supervolcano, which erupted around 200,000 years before the asteroid impact that is widely believed to have caused the dinosaurs’ extinction.

Studying volcanic winters

The study, which focuses on these gases, reveals that their release could have caused global temperatures to drop by up to 18 degrees Fahrenheit (10 degrees Celsius). 

This discovery contributes to the ongoing debate among paleontologists and scientists regarding the precise cause of the dinosaurs’ demise. The research aligns with the “press-pulse extinction model,” which suggests that a combination of factors led to the extinction event.

Unstable climate conditions

“Our research demonstrates that climatic conditions were almost certainly unstable, with repeated volcanic winters that could have lasted decades, prior to the extinction of the dinosaurs,” said study co-author Don Baker, a geologist at McGill University in Montreal. 

“Our work helps explain this significant extinction event that led to the rise of mammals and the evolution of our species.”

How the research was conducted 

The team analyzed sulfur and fluorine compounds in samples from the Deccan Traps in India’s Western Ghats, near Bombay. They employed synchrotron radiation x‐ray fluorescence spectrometry to measure these compounds’ concentrations. Baker likened the process to cooking pasta, where a small amount of the salt in boiling water is absorbed by the pasta. 

Similarly, the team estimated the volume of sulfur and fluorine gases that entered the atmosphere during the Cretaceous period based on the compounds’ presence in the lava rocks.

Critical insights 

Notably, the researchers found that the highest sulfur content, as high as 1,800 parts-per-million, correlated with a drop in temperature during the late Cretaceous period. They estimated that between 86,000 and 466,000 cubic-kilometers of sulfur gas were released into the atmosphere, leading to significant climatic changes.

Although the team did not attribute major climate change to fluorine gases, they noted these gases’ toxic local effects, including acid rain, crop failure, and livestock poisoning, as observed in historical accounts of the Laki volcano eruptions in Iceland in the 18th century. These effects might have similarly impacted the dinosaurs’ environment.

Multiple triggers

The researchers conclude that the Deccan Traps’ volcanic activity set the stage for a global biotic crisis by triggering repeated short volcanic winters. 

However, they believe the “final blow” was the Chicxulub asteroid impact in Mexico, which caused massive environmental devastation. This impact, combined with the preceding volcanic activity, likely accelerated the dinosaurs’ extinction.

Study implications

The study, published in the journal Science Advances, highlights the intricate interplay of environmental factors leading up to one of Earth’s most significant extinction events. 

“Our dataset indicates that volcanic-driven climate disturbance was already underway,” the researchers noted, underscoring the complexity of the events that led to the end of the dinosaur era.

More about volcanic winters

As mentioned above, volcanic winters are climatic events resulting from major volcanic eruptions that inject large amounts of ash and sulfur dioxide (SO2) into the Earth’s stratosphere. Let’s dig a little deeper.

Mechanism of volcanic winters

Eruption Dynamics: Large volcanic eruptions expel ash and gases high into the stratosphere.

Formation of Sulfur Aerosols: The sulfur dioxide reacts to form sulfuric acid aerosols, which reflect sunlight away from Earth, leading to cooling.

Longevity in the Stratosphere: These aerosols can remain in the stratosphere for years, prolonging their cooling effect.

Volcanic winters’ impact on climate

Global Cooling: Volcanic winters typically result in a noticeable drop in global or regional temperatures.

Weather Pattern Disruptions: These temperature changes can alter normal weather patterns, causing droughts or excessive rainfall.

Agricultural Impact: Reduced sunlight and cooler temperatures adversely affect crop yields, potentially leading to famines.

Historical instances

The Year Without a Summer (1816): Following the 1815 eruption of Mount Tambora, 1816 experienced dramatically lowered temperatures, leading to widespread crop failures.

The Toba Catastrophe (Around 74,000 Years Ago): The Toba super-volcano eruption is believed to have caused a decade-long volcanic winter, severely impacting early human populations.

Modern concerns and future risks

Today, advanced monitoring and climate modeling allow for better prediction and preparedness for volcanic winters. A major eruption today could significantly impact our globalized society, emphasizing the need for continued vigilance and preparedness.

In summary, volcanic winters, though rare, pose a significant risk due to their ability to alter global climates and disrupt human activities. Understanding and preparing for these events is crucial in our increasingly interconnected world.


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