New chemical analysis sends climate warming signal
A study of ancient carbonate crystals in Colorado suggests that the Earth’s climate is more sensitive to changes in atmospheric carbon dioxide than believed.
Based on the chemical analysis of rocks from the Green River formation, scientists think that a doubling of CO2 from pre-industrial times could raise the global temperature by a whopping 3 degrees Celsius.The study team from Binghamton University took a close look at the crystals that formed 50 million years ago during a hothouse climate. They found that CO2 levels during this time may have been as low as 680 parts per million, nearly half the 1,125 ppm predicted by previous experiments.
Based on their results, past predictions significantly underestimate the impact of greenhouse warming
“The significance of this is that CO2 50 million years ago may not have been as high as we once thought it was, but the climate back then was significantly warmer than it is today,” said Binghampton researcher Tim Lowenstein.
“Take notice that carbon dioxide 50 million years ago may not have been as high as we once thought it was. We may reach that level in the next century, and so the climate change from that increase could be pretty severe, pretty dramatic. CO2 and other climate forcings may be more important for global warming than we realized,” Lowenstein said.
The only direct measurement of atmospheric carbon dioxide is from ice cores, which only go back less than 1 million years. Lowenstein and his team are trying to develop ways to estimate ancient carbon dioxide in the atmosphere using indirect proxies. He said that their approach is different than any ever undertaken.
“These are direct chemical measurements that are based on equilibrium thermodynamics,” he said. “These are direct laboratory experiments, so I think they’re really reliable.
Lowenstein wants to look at nahcolite deposits in China to confirm the results found in Colorado.
The study, “Eocene atmospheric CO2 from the nahcolite proxy,” was published Oct. 23 in Geology.