New study shows Earth's heat lasted 485 million years

A new study provides the most detailed glimpse yet into how Earth's surface temperature has changed over the past Phanerozoic era– The most recent of the four geological eras on the Earth's geological time scale, which covers the time period from 538.8 million years ago to the present.

The new curve reveals that The Earth's temperature has changed more than previously thought over much of the Phanerozoic Eon. He also stresses that the Earth's temperature is closely related to the amount of carbon dioxide in the atmosphere.

The international team that conducted the study created the temperature curve using an approach called data assimilation.

The fossil distribution of cold- or heat-resistant animals and plants provides some of the first clues about ancient temperatures. Chemical analysis of ancient shells and fossilized microorganismsUsing preserved organic matter, scientists can reconstruct past ocean temperatures. Even rocks and minerals can help map past climates. For example, salt deposits They are signs of an ancient arid environment, and Gallondolite It is a mineral that can only form in cold water.

The researchers combined this data from the geological record into a database called Fantastic (Integrated surface temperature curve project using the Phanerozoic technique) and its integration with modern climate models.

“This method was originally developed for weather forecasting,” he explains. Emily Goodlead author of the new paper and former postdoctoral researcher at Smithsonian National Museum of Natural History And the University of Arizona. “Instead of using it to predict future weather, we’re using it here to predict ancient climates.”

The Arizona team compiled more than 150,000 published data points, and their colleagues at the University of Bristol created more than 850 model simulations of what Earth’s climate might have looked like at different times based on the location of continents and the composition of the atmosphere. The researchers then used data assimilation to combine these two lines of evidence and create a more accurate curve of how Earth’s temperature has changed over the past 485 million years.

The new curve reveals that temperatures varied more widely during the Phanerozoic than previously thought. Over the eon, the average global surface temperature ranged from 52 to 97 degrees Fahrenheit (11 to 36 degrees Celsius). Extreme heat periods were most often associated with elevated levels of the greenhouse gas carbon dioxide in the atmosphere, with other factors such as solar input playing a minor role.

Knowing how Earth's temperature has fluctuated over deep time provides crucial context for understanding modern climate change.

“If you study the past two million years, you won't find anything like what we expect in 2100 or 2500,” he says. Scott Wingthe Smithsonian Curator of the Department of Paleobotany whose research focuses on Paleocene and Eocene Thermal Maximuma period of rapid global warming that began 55 million years ago.

“We need to go back to more distant periods when the Earth was really warm, because that's the only way we'll be able to get a better understanding of how the climate will change in the future.”

The curve shows that Earth has been cooler over the past 10 to 20 million years than it was over the previous 450 million years. But climate change caused by greenhouse gas emissions is now warming the planet at a much faster rate than the fastest warming events of the Phanerozoic.

“Humans, and the species we share this planet with, are adapted to cold climates,” concludes Jessica Tierney, a paleoclimatologist at the University of Arizona. “A rapid shift to a warmer climate is dangerous.” Fossil records indicate that some episodes of rapid climate change during the Phanerozoic coincide with mass extinctions.

While the new paper is the most detailed and robust study of temperature change to date, it is far from a complete project, according to Brian Hoopercurator of the micropaleontology collection, who studies microscopic fossils to understand environmental conditions during Cretaceous, the warmest period of the Phanerozoic Era.

“We all agree that this is not the final curve,” says Huber. “Researchers will continue to uncover additional evidence about the deep past, which will help to modify this curve in the future.”

“Complete Study”Earth's surface temperature history over 485 million years“Published in the magazine” sciences And it could be Found online here.

Additional materials and interviews provided by Smithsonian Institution and University of Arizona.