![]() ![]() In addition, only fossil fuels are consistent with the isotopic fingerprint of the carbon in today’s atmosphere. Only fossil fuels-which are the remains of millions of years of carbon uptake by plants-contain enough carbon to produce such a massive change in such a short time. The increase between the year 1800 and today is 70% larger than the increase that occurred when Earth climbed out of the last ice age between 17,500 and 11,500 years ago, and it occurred 100-200 times faster. ![]() At the end of the last ice age around 20,000 years ago, it was 280 ppm. More detailĭuring all of the cycles between ice ages and warm periods over the past million years, atmospheric carbon dioxide never climbed higher than 300 parts per million. Graph by NOAA based on data from Lüthi, et al., 2008, via NOAA NCEI Paleoclimatology Program. ![]() In fact, on the geologic time scale, the increase from the end of the last ice age to the present looks virtually instantaneous. The increase over the last 60 years is 100 times faster than previous natural increases. Throughout that time, CO 2 was never higher than 300 ppm (light purple dot, between 300,000 and 400,000 years ago). The peaks and valleys in the line track ice ages (low CO 2) and warmer interglacials (higher CO 2). Global atmospheric carbon dioxide (CO 2) in parts per million (ppm) for the past 800,000 years based on ice-core data (purple line) compared to 2021 concentration (dark purple dot). ![]()
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