The year 2015 saw a record atmospheric CO<sub>2</sub> growth rate associated with a weaker than usual land carbon sink. Paradoxically, it was also the greenest year since 2000 according to satellite observations of vegetation greenness. To reconcile these two seemingly paradoxical observations, we examined the patterns of CO<sub>2</sub> fluxes using two atmospheric inversions. Inversion results indicate that the year 2015 had a higher than usual northern land carbon uptake in spring and summer, consistent with the greening anomaly. This higher uptake was however followed by a larger source of CO<sub>2</sub> in autumn, suggesting a coupling between growing season uptake and late season release of CO<sub>2</sub>. For the tropics and Southern Hemisphere, a strong and abrupt transition toward a large carbon source for the last trimester of 2015 is discovered, concomitant with the El Niño development. This abrupt transition of terrestrial tropical CO<sub>2</sub> fluxes between two consecutive seasons is the largest ever found in the inversion records.