Washington (AUS): A ground-breaking new study led by the Smithsonian and University of Arizona reveals a detailed history of the Earth’s temperature fluctuations across the past 485 million years — and describes for the first time how ancient land plants contributed to changes in the global climate.
Deciphering Earths Climate Past
The research, published in the prestigious journal Science, provides a holistic temperature curve tracking Earth’s global mean surface temperature (GMST) over the Phanerozoic Eon of roughly the past 540 million years.
Because the fossil record is so spotty, researchers had challenged in constructing an accurate temperature curve for that period of time. Drawing from a remarkable dataset of thousands of geochemical records, and using climate modeling simulations, researchers have now assembled the most detailed picture yet of how Earth’s temperatures changed over 66 million years.
According to the findings, Earth’s temperature has fluctuated much farther than expected—between about 52 and 97 degrees Fahrenheit (11 and 36 degrees Celsius) over Phanerozoic Eon! Recknberg says the team’s method of data assimilation, originally created for weather forecasting, has been key to piecing together old cliamtes into a more coherent picture.
The Dominant Role of CO2
The study provides further evidence that of all the greenhouse gases, carbon dioxide (CO2) exerts by far the largest control on Earth’s temperature. High concentrations of this greenhouse gas were present in warm periods, and these levels fell during more cold periods.
“”Our research complements Dire Predictions by offering additional insight into this relationship between atmospheric carbon dioxide levels and long-term global temperatures,” said corresponding author Jessica Tierney, an assistant professor in the Department of Geosciences at the University of Arizona. “Nearly everything about the climate record suggests that as carbon dioxide goes, so goes temperature: when CO2 is low, it’s cold; when CO2 is high, it’s warm.”
In this case, the results are a sobering demonstration of how CO2 can shape the climate of our planet. While Earth’s current mean surface temperature of 15 degrees Celsius (59 degrees Fahrenheit) is cooler than it was for much of the Phanerozoic, human-caused greenhouse gas emissions are warming the planet significantly more rapidly than even the fastest natural fluctuations in ancient climates.
Conclusion
This is the groundbreaking study that underpins much of our current understanding of global warming and gives important context for the climate crisis we face. As these proxies expose long swings of the planetary thermostat over 485 million years and clarify atmospheric carbon dioxide’s essential role in driving this roller-coaster ride, we gain a richer sense of just how fragile Earth’s climate system appears. With the onset of anthropogenic climate change, this view is a stark reminder how rapidly modern warming could wreak havoc upon species and ecosystems that had become accustomed to long periods of stability in conditions during the Holocene epoch. The results highlight the pressing need to decrease greenhouse gas emissions and prevent increased destabilization of our planet’s delicate climate.
