According to a new investigation of the greenhouse gas’s role in ice ages over the millennia, Carbon dioxide in the earth’s atmosphere has risen to its highest level in at least 2.1 million years.

According to a new investigation of the greenhouse gas’s role in ice ages over the millennia, Carbon dioxide in the earth’s atmosphere has risen to its highest level in at least 2.1 million years.


Researchers including Columbia University’s Baerbel Hoenisch drilled into the ocean floor off the coast of Africa to remove shells of ancient marine animals called foraminifera that contain climate records, according to the study published today on Science’s Web site. Previous evidence of CO2 concentrations found in columns of Arctic ice go back just 800,000 years.

Carbon dioxide, which traps heat close to earth, is the main contributor to global warming, threatening to raise sea levels and disrupt food production and water supplies, United Nations scientists have said.

If the world continues to burn coal and oil and cut down forests that store carbon, the amount of CO2 in the atmosphere may more than double to 900 parts per million in the next century, the UN’s Environment Programme Executive Director Achim Steiner has said.

Negotiators at UN-sponsored talks are attempting to set limits on CO2 emissions. Delegates are focused on restricting output of the gas, which has grown 2 percent since industrialization in the 1800s.

“With unabated emissions, many trends in climate will likely accelerate, leading to an increasing risk of abrupt or irreversible climatic shifts,” 10 universities said recently in a report suggesting that climate change was underestimated.

The United Nations Intergovernmental Panel on Climate Change in 2007 blamed global warming on emissions of such gases and warned of increased flooding and drought as temperatures continue to rise. Greenhouse gases also include water vapor, methane and nitrous oxide.


Other evidence of greenhouse gas concentration has been discovered in ice. Polar researchers reported last year in the journal Nature that carbon dioxide was at an 800,000-year high, after studying bubbles trapped in ice drilled from the Antarctic.

Hoenisch and colleagues investigated the role of the carbon cycle in climate change and concluded that CO2 was probably not responsible for lengthening the time between major ice ages to 100,000 years from 40,000, countering a supposition that massive ice sheets grew and receded because of gradually decreasing levels of carbon dioxide.

Even with the likelihood of the earth warming up in the coming centuries, we’re headed for another ice age at some point thousands of years in the future, said McManus.

“The earth is moving into an increasingly glaciated state,” he said. “It’s just that the intervals between ice ages, which we’re living in now, have become longer and warmer.”

For more information, look at Jeremy Van Loon's story on the issue:

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