A new model disputes the Chicxulub meteor theory for the extinction of dinosaurs. Dartmouth University scientists used a simulation to analyze thousands of scenarios, exploring fossil records spanning a million years.
The model points to India's Deccan Traps mega-volcano, emitting massive carbon dioxide and sulfur dioxide 300,000 years before the asteroid impact, as the extinction driver. This volcano released trillions of tons of these gases over nearly a million years.
Simulation Tested 300,000 Likely Scenarios of Dinosaur Extinction
Dartmouth researchers used an objective approach, letting computer code make decisions without human bias. They input geological and climate data from deep-sea core samples with fossils dating back 67-65 million years.
Carbon and oxygen isotopes in foraminifera fossils were used to estimate pre- and post-extinction global temperatures. The study marks the first independent estimation of volatile emissions based on their environmental impact.
Volcanic eruptions historically contributed to mass extinctions, and this study sought to quantify their effects. The computer model autonomously analyzed data to determine the necessary carbon dioxide and sulfur dioxide levels for observed climate and carbon cycle disruptions in geological records, aligning with Deccan Traps emissions.
The 'Long-term Ocean-atmosphere-Sediment Carbon Cycle Reservoir' (LOSCAR) model was employed to track carbon atom movement one million years before and after the dinosaur extinction, offering an impartial exploration of volcanic emissions' role in the event.
The LOSCAR model utilized raw geological data from deep-sea core samples to replicate the ancient carbon cycle, tracing carbon's movement from atmospheric carbon dioxide to oceanic foraminifera and then to fossilized foraminifera in sediment.
To minimize bias, the researchers employed Bayesian Inversion, a statistical technique that reversed the simulation in time to determine probable scenarios leading to fossil records, as opposed to the typical forward modeling approach.
This unique approach allowed the computer model to work with minimal prior information and removed preconceived notions from the analysis.
Running the simulation backward required substantial computational resources. The study published in the journal Science used 128 computer processors running scenarios on a total of 512 cores in parallel to simulate the pre- and post-extinction atmosphere related to the last days of the dinosaurs.
READ ALSO: Dinosaurs Could Have Been Declining 2 Million Years Before the Asteroid Impact, Study Reveals
Climate Change Gas From Volcanic Eruptions Led To Dinosaur Extinction
Conducting parallel simulations significantly accelerated the process, reducing the computational time from a potential year down to just a few days. The processors regularly compared their outcomes, facilitating the analysis of elevated carbon dioxide and sulfur dioxide emissions during the Cretaceous-Paleogene extinction event, mainly attributed to India's massive volcanic activity.
However, not all experts are entirely convinced. Some argue that changes in oxygen isotope ratios in foraminifera fossils could result from variations in seawater composition, not just climate. They also suggest that the study doesn't definitively rule out the asteroid impact as a contributing factor to the extinction.
Some researchers propose that the asteroid impact might have induced significant cooling due to the immense amount of soot and dust it ejected, potentially playing a role in the extinction event.
The Dartmouth researchers emphasize that they are conveying the findings of their computer model and that the model offers insights into how geological records align with their analysis, regardless of existing beliefs or ongoing scientific debates.
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