Carbon dioxide levels dating far back

Researchers have reconstructed atmospheric carbon dioxide levels over the past 2.1 million years in the sharpest detail yet, shedding new light on its role in the earth's cycles of cooling and warming.as the cause for earth's ice ages growing longer and more intense some 850,000 years ago.Last month, the atmospheric concentration of carbon dioxide (CO2) as measured at Amsterdam Island, in the southern Indian Ocean, for the first time exceeded the symbolic value of 400 ppm, or 0.04%. Researchers have reconstructed atmospheric carbon dioxide levels over the past 2.1 million years in the sharpest detail yet, shedding new light on its role in the Earth's cycles of cooling and warming.The planet has undergone cyclic ice ages for millions of years, but about 850,000 years ago, the cycles of ice grew longer and more intense—a shift that some scientists have attributed to falling CO did not change much over the past 20 million years, but the resolution wasn't high enough to be definitive," said Hönisch.

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The authors show that peak CO is at 385 parts per million, or 38% higher.Monthly CO in order to understand how quickly fossil fuel pollution is changing our climate," said Pieter Tans, senior scientist with NOAA's Global Monitoring Division. They do not depend on any models, but they help us verify climate model projections, which if anything, have underestimated the rapid pace of climate change being observed." The concentration of CO in the atmosphere increases every year, and the rate of increase is accelerating.The early years at Mauna Loa saw annual increases averaging about 0.7 ppm per year, increasing to about 1.6 ppm per year in the 1980s and 1.5 ppm per year in the 1990s.Two million years ago, the earth underwent an ice age every 41,000 years.But some time around 850,000 years ago, the cycle grew to 100,000 years, and ice sheets reached greater extents than they had in several million years—a change too great to be explained by orbital variation alone.

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