Studies diverge substantially on the actual magnitude of the North American carbon budget. This is due to the lack of appropriate data and also stems fromthe difficulty to properly model all the details of the flux distribution and transport inside the region of interest. To sidestep these difficulties,weuse here a simple budgeting approach to estimate land-atmosphere fluxes across North America by balancing the inflow and outflow of CO 2 from the troposphere. We base our study on the unique sampling strategy of atmospheric CO2 vertical profiles over North America from the National Oceanic and Atmospheric Administration/Earth System Research Laboratory aircraft network, from which we infer the three-dimensional CO 2 distribution over the continent. We find a moderate sink of 0.5 ± 0.4 PgCy-1 for the period 2004-2006 for the coterminous United States, in good agreement with the forest-inventory-based estimate of the first North American State of the Carbon Cycle Report, and averaged climate conditions. We find that the highest uptake occurs in the Midwest and in the Southeast. This partitioning agrees with independent estimates of crop uptake in the Midwest, which proves to be a significant part of the US atmospheric sink, and of secondary forest regrowth in the Southeast. Provided that vertical profile measurements are continued, our study offers an independent means to link regional carbon uptake to climate drivers.
|Number of pages
|Proceedings of the National Academy of Sciences of the United States of America
|Published - Oct 26 2010
All Science Journal Classification (ASJC) codes
- Atmospheric composition
- Carbon cycle
- Greenhouse gases