Comparison of modelled and observed carbon flux anomalies. Global carbon balance during 1992/93 and 1998 using modelled and measured data of carbon sources and sinks and atmospheric reference data. Negative fluxes denote carbon uptake. Negative values of measured atmospheric ΔCO2 denote a reduction it's rate of increase. Temperature and precipitation anomalies are calculated from the climate data set . The histogram on the left is computed from measured carbon flux anomalies of last 25 years to illustrate the exceptional perturbation of the global carbon cycle in the two periods under investigation .