Warming Climate, Greening Earth, Carbon Sink

Model Simulates Leaf Area Changes: We compare monthly Leaf Area Index (green leaf area per unit ground area, LAI) anomalies for the boreal zone, derived from a recent version of the AVHRR satellite data, with monthly LAI anomalies independently predicted by the LPJ (Lund-Potsdam-Jena) Dynamic Global Vegetation Model, a biogeochemical process model, driven by monthly climate observations and by the global mean CO2 concentration increase. Both simulated and observed LAI anomalies show an overall increasing trend, but periods lasting several years with positive or negative deviations from the trend can be discerned in the observations and are correctly simulated (figure below). The pattern of LAI anomalies within each year is in general correctly simulated, although discrepancies are seen in 1988 and 1996. The similarity between the model results and the observations is seen not only for the whole boreal zone, but also for each separate continent, even though the patterns differ substantially among the continents.

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