Climate in the olden days may be more sensitive to atmospheric carbon dioxide than scientists once believed, according to a new study.

Researchers from the Binghamton University studied nahcolite crystals retrieved from the Green River formation in Colorado. These crystals were formed about 50 million years ago due to a hothouse climate. The team found that the carbon dioxide levels at this time may have been only around 680 parts per million (ppm), which is much lower than the previously predicted 1,125 ppm.

This entails that past predictions may have significantly underestimated greenhouse effect impact on the Earth's climate all those years ago.

"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 Tim Lowenstein, a professor from the Binghamton University and one of the researchers.

Today's atmospheric carbon dioxide levels have reached about 400 ppm. The growing rise in carbon dioxide levels is subsequently connected to worsening global warming, resulting to rise in temperatures around the world.

Based on current projections, the continued increase in carbon dioxide levels will result in a rise in temperatures to three degrees Centigrade (37 degrees Fahrenheit). Not only will the heat have a significant impact on climate change, it may also cause rise in water levels that could erode mountains and even cause countries to sink.

Today's carbon dioxide levels are getting frighteningly close to the level of carbon dioxide present millions of years ago.

"We may reach that level in the next century, and so the climate change from that increase could be pretty severe, pretty dramatic." Lowenstein said.

Traditionally, the only way to directly measure carbon dioxide levels is through ice cores which can only go back to less than a million years. The researchers are trying to find new ways to determine ancient carbon dioxide levels through indirect proxies.

Lowenstein said that the technique they used is different than others but is no less reliable. However, he still wants to study nahcolite crystals from China to confirm his findings from the ones in Colorado.

The team's research was published in last month's issue of the journal Geology.