Introduction to the Great Dying

252 million years ago, a series of massive volcanic eruptions in what is now Siberia released approximately 100 trillion metric tons of carbon dioxide (CO2) into the atmosphere over a period of a million years. This catastrophic event, known as the "Great Dying," led to the demise of most animal life on Earth. Recent research has shed light on how this event also profoundly altered Earth’s ecosystems.

Linking the Great Dying to Global Temperature Rise

An international team of researchers employed climate models and analyzed plant fossils to establish a connection between the Great Dying and an 18-degree Fahrenheit (10 degrees Celsius) increase in average global temperatures. The findings, published in a study in the journal Frontiers in Earth Science, offer insights into how current carbon dioxide emissions could drastically change the planet.

Focusing on Specific Time Periods

The researchers concentrated on five distinct time periods spanning parts of the Permian and Triassic periods: the Wuchiapingian and Changhsingian of the Permian, and the Induan, Olenekian, and Anisian of the Triassic. The Great Dying marks the transition from the Permian to the Triassic period, often referred to as the Permian-Triassic mass extinction or the Permian-Triassic Boundary. Notably, the Triassic period is also when the ancestors of dinosaurs, which survived the Great Dying, began to thrive.

Adjustments in Life on Earth

According to lead author Maura Brunetti, a researcher at the University of Geneva’s Group of Applied Physics Institute for Environmental Sciences, "Life on Earth had to adjust to repeated changes in climate and the carbon cycle for several million years after the Permian-Triassic Boundary." This adjustment was necessary due to the significant alterations in the planet’s ecosystems.

Analyzing Biome Changes

Brunetti and her team estimated changes within six different biomes across the specified time periods by analyzing plant fossils and running computer model simulations under various temperature and CO2 level scenarios. The biomes included tropical everwet, seasonal tropical or temperate, and desert biomes. The researchers found that the Permian period was cold, while the Olenekian and Anisian periods were much hotter, with a transition marked by an approximately 10°C (18 degrees Fahrenheit) increase in mean global surface air temperature.

Shifts in Biomes and Ecosystems

The study revealed significant changes in biomes during this transition. Tropical everwet and summerwet biomes emerged in the tropics, replacing desert landscapes, while the warm-cool temperate biome shifted towards polar regions, leading to the disappearance of tundra ecosystems. Essentially, deserts near the equator became tropical, and cold tundra landscapes closer to the poles were replaced by more temperate forests.

Implications for the Future

The "shift in vegetation cover can be linked to tipping mechanisms," or irreversible shifts, between stable climate periods, according to Brunetti. This creates a potential framework for understanding tipping behavior in the climate system in response to present-day CO2 increases. If CO2 emissions continue at their current rate, the level of emissions that caused the Permian-Triassic mass extinction could be reached in approximately 2,700 years, a much faster timescale than the Permian-Triassic Boundary emissions.

Conclusion

While the researchers emphasize the need for further study to confirm their findings, the study serves as a stark warning: continued human emissions of CO2 could, in the very long run, change the planet more dramatically than the Great Dying. This underscores the importance of addressing climate change to mitigate its potential catastrophic effects on Earth’s ecosystems.