What was done
In a study of tropical forests, the authors say they "simulated and analyzed 1982-1999 Amazonian, African, and Asian carbon fluxes using the Biome-BGC prognostic carbon cycle model driven by National Centers for Environmental Prediction reanalysis daily climate data," after which they "calculated trends in gross primary productivity (GPP) and net primary productivity (NPP)."

What was learned
Solar radiation variability was found to be the primary factor responsible for interannual variations in GPP, followed by temperature and precipitation variability, while in terms of GPP trends, Ichii et al. report that "recent changes in atmospheric CO2 and climate promoted terrestrial GPP increases with a significant linear trend in all three tropical regions."  In the Amazonian region, the rate of GPP increase was 0.67 PgC year^-1 per decade, while in Africa and Asia it was about 0.3 PgC year^-1 per decade.  Likewise, they report that "CO2 fertilization effects strongly increased recent NPP trends in regional totals."

What it means
In response to the supposedly most dramatic global warming of the past two millennia, which is claimed to have been driven by the even more unprecedented concomitant increase in atmospheric CO2 concentration, earth's tropical forests appear to have fared remarkably well, growing ever more robustly and removing ever more carbon from the atmosphere in some of the hottest places on the planet.

Is this the stuff of which catastrophes are made?  Or is this the stuff that reveals such claims of catastrophe to be pure and utter nonsense?