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    LOS ANGELES, Oct. 11 (Xinhua) -- The level of carbon dioxide in Earth's atmosphere has not been this high for at least 1.5 million years, a new study suggests.

    The current carbon dioxide level is 387 parts per million, above the level of about 280 parts per million that existed without exception for 1.6 million years until the dawn of the Industrial Age, according to the study by researchers at the University of California in Los Angeles (UCLA).

    The researchers came to the conclusion by analyzing fossilized algae, said the study appearing in Oct. online edition of the journal Science.

    Current measurement techniques have used measurements of gases in trapped bubbles of air in Antarctic ice. But that has allowed scientists to measure historic atmospheric carbon dioxide levels back only 800,000 years.

    The researchers were able to prove that single-celled creatures living in oceans have differing proportions of the elements of boron and calcium in their shells.

    By measuring those elements in fossils, the researchers are able to deduce the amount of carbon dioxide in the ancient atmosphere.

    "The last time carbon dioxide levels are apparently as high as they are today -- and were sustained at those levels -- global temperatures were 5-10 degrees Fahrenheit higher than they are today, the sea level was approximately 75-120 feet higher than they are today," said leader researcher Aradhna Tripati, a UCLA assistant professor of Earth and space studies.

    "Carbon dioxide is a potent greenhouse gas, and geological observations that we have now 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."

    Tripati said this is the first evidence that the current carbon dioxide levels are unprecedented further back than 800,000 years.

    "We can now have confidence in making statements about how carbon dioxide has varied throughout history," she said.

    The UCLA findings come as Congress debates a bill to cap the amount of carbon dioxide that can be emitted by industry in the United States. A major point of contention is the argument by some that carbon dioxide levels are naturally-variable, and that man has no impact on them.