The
global rate of fossil fuel combustion continues to rise, but the amount of CO2
accumulating in the atmosphere has not increased accordingly (Tans et al., 1990; Conway et al., 1994; Wofsy,
2001). The causes for this discrepancy
are widely debated (Houghton,
2003). In particular, the location and
drivers for the interannual variability of atmospheric CO2 are
highly uncertain. Here we examine links
between global atmospheric CO2 growth rate (CGR) and the climate anomalies
of biomes based on ten years (1986-1995) of global climate data and
accompanying satellite data sets. Our
results show that four biomes, the tropical rainforest, tropical savanna, C4
grassland and boreal forest, and their responses to climate anomalies, are the
major climate-sensitive CO2 sinks/sources that control the CGR. The nature and magnitude by which these
biomes respond to climate anomalies are generally not the same. However, one common influence did emerge from
our analysis; the extremely high CGR that was observed for the one extreme El
Niño year was caused by the response of the tropical biomes (rainforest,
savanna and C4 grassland) to temperature.
Author: C. Yi, T. Zhou, P. S. Bakwin, L. Zhu and R. K. Monson
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