[Grad-postdoc-assn] ASP Seminar TODAY

[Gabriele Pfister]

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ASP Seminar Series

SPEAKER:  Pieter Tans, Earth System Research Laboratory, NOAA Boulder
TITLE:        Acceleration of the rate of growth of atmospheric  
carbon dioxide
WHEN:       Wednesday, May 31st,  2006 at 11 a.m. (refreshments  
beforehand)
WHERE:     Foothills Laboratory, FL2, Room 1022

ABSTRACT:
When Dave Keeling started continuous measurements of CO2 on Mauna Loa  
in 1958 the observed mean growth rate for 1959 through 1963 was  
approximately 0.76 ppm/year, while the average rate of fossil fuel  
consumption was 2.5 GtC (billion metric tons of carbon)/year. The  
mean growth rate for 2001 through 2005 is 2.1 ppm/year, and a  
preliminary estimate for the rate of fossil fuel burning is 7.3 GtC/ 
year. It appears that over several decades the atmospheric increase  
maintains an almost constant proportion to the rate of fossil fuel  
burning, except during the early 1990s. This is actually surprising  
given what we expect the ocean response to the historical atmospheric  
CO2 increase to be.
We have compiled a second growth rate estimate based on global marine  
air data since 1980. Mauna Loa tracks the global rate well. One  
standard deviation of the differences between the two is 0.26 ppm/ 
year. There is considerable year-to-year variation in the atmospheric  
increase measured at Mauna Loa, with a standard deviation of 0.46 ppm/ 
year relative to the long-term trend. The interannual variation is  
visibly related to global temperature anomalies. We have constructed  
from the data a delayed response curve of the CO2 growth rate to  
temperature. The response changes sign at a delay of about 0.5 year.  
We could not detect a response to other global or regional climate  
anomalies such as precipitation. Subtraction of the calculated  
response of CO2 to temperature anomalies significantly decreases the  
“unexplained” part of the interannual variation of the CO2 growth rate.

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