CO2 levels on Earth 15 mln yrs ago were as high as they are today

October 9th, 2009 - 2:46 pm ICT by ANI  

Washington, October 9 (ANI): In a new research, a scientist of Indian origin has determined that carbon dioxide (CO2) levels on Earth 15 million years ago were as high as they are today.

The research was conducted by Aradhna Tripati, a UCLA (University of California, Los Angeles) assistant professor in the department of Earth and space sciences and the department of atmospheric and oceanic sciences, and colleagues.

“The last time carbon dioxide levels were apparently as high as they are today - and were sustained at those levels - global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland,” said Tripati.

“Carbon dioxide is a potent greenhouse gas, and geological observations that we now have for the last 20 million years lend strong support to the idea that carbon dioxide is an important agent for driving climate change throughout Earth’s history,” she said.

By analyzing the chemistry of bubbles of ancient air trapped in Antarctic ice, scientists have been able to determine the composition of Earth’s atmosphere going back as far as 800,000 years, and they have developed a good understanding of how carbon dioxide levels have varied in the atmosphere since that time.

“We are able, for the first time, to accurately reproduce the ice-core record for the last 800,000 years - the record of atmospheric C02 based on measurements of carbon dioxide in gas bubbles in ice,” Tripati said.

“We then applied this technique to study the history of carbon dioxide from 800,000 years ago to 20 million years ago,” she said.

“We report evidence for a very close coupling between carbon dioxide levels and climate. When there is evidence for the growth of a large ice sheet on Antarctica or on Greenland or the growth of sea ice in the Arctic Ocean, we see evidence for a dramatic change in carbon dioxide levels over the last 20 million years,” she added.

According to Tripati, “A slightly shocking finding is that the only time in the last 20 million years that we find evidence for carbon dioxide levels similar to the modern level of 387 parts per million was 15 to 20 million years ago, when the planet was dramatically different.”

It has been known that modern-day levels of CO2 are unprecedented over the last 800,000 years, but the finding that modern levels have not been reached in the last 15 million years is new. (ANI)

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