The exponential increase in anthropogenic atmospheric carbon dioxide and its relation to human population growth
David J. Hofmann, NOAA/ESRL, Boulder, CO
That carbon dioxide is increasing in the atmosphere is a well-known fact and the foremost concern in global climate change. Not so well-known is that the anthropogenic component (atmospheric value reduced by the pre-industrial value of 280 ppm) of atmospheric carbon dioxide has been increasing exponentially with a doubling time of about 35 years since the beginning of the industrial revolution (the late 1700's). Even during the 1970's, when fossil fuel emissions dropped sharply in response to the “oil crisis” of 1973, the anthropogenic atmospheric carbon dioxide level continued increasing exponentially at Mauna Loa where the record dates back to the late 1950's. Since the growth rate (time derivative) of an exponential has the same characteristic lifetime as the function itself, the carbon dioxide growth rate is also doubling at the same rate. This explains the observation that for linear growth rates, carbon dioxide increased from less than 1 ppm per year to more than 2 ppm per year in the past 40 years. This accelerating growth rate, which has caused some concern, is simply the outcome of exponential growth in carbon dioxide. It is argued that this is expected since world population and Gross Domestic Product are increasing exponentially with similar rates of growth.
Extended Abstract (172K)
Poster Session 5, Climate trends and extremes
Wednesday, 14 January 2009, 2:30 PM-4:00 PM, Hall 5
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