Scientists: Last Great Heat Spike (PETM) Saw Climate Far More Sensitive To CO2 Than Thought
Scientists have discovered how a spike in carbon dioxide over 50 million years ago may have caused global temperatures to soar to their highest levels in 66 million years—something they have dubbed a "scary finding" in relation to climate change today. The climate model of the Early Eocene—which took place between 48 to 54 million years ago—has provided researchers with the most detailed picture yet of how temperatures rose to 14 degrees Celsius above what they are today.
"We were surprised that the climate sensitivity increased as much as it did with increasing carbon dioxide levels," Jiang Zhu, an environmental research fellow at the University of Michigan, said in a statement. "It is a scary finding because it indicates that the temperature response to an increase in carbon dioxide in the future might be larger than the response to the same increase in CO2 now. This is not good news for us."
The Early Eocene included the Paleocene-Eocene Thermal Maximum (PETM). During this time, carbon dioxide levels rose significantly and global temperatures soared. "Geological evidence shows that during the Early Eocene, Earth's surface was at least 14 degrees Celsius warmer on average than right now and that the difference between the equator and polar temperatures was much smaller," Zhu told Newsweek. "The poles were ice free. There were palm trees near the North Pole."
At this time, CO2 levels were around 1,000 parts per million by volume (ppmv). This is over double what they are today. In May, a CO2 level of 414 ppmv was recorded by the Mauna Loa Atmospheric Baseline Observatory at the National Oceanic and Atmospheric Administration (NOAA)—the highest concentration ever seen over 61 years' worth of observations. It is thought atmospheric CO2 will surpass 1,000 ppmv by the end of the century if nothing is done to limit its release.
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https://www.newsweek.com/co2-climate-change-early-eocene-scary-1459956