What was done
The authors used a mechanistic pasture simulation model (PaSim) to predict changes in net primary productivity and carbon stocks in differently-managed grasslands in response to increased atmospheric CO2 concentration and climate change.

What was learned
Elevated CO2 alone, or in combination with increased air temperature, enhanced net primary productivity at all simulated sites by 30 to 40%.  In addition, the effects of elevated CO2 and elevated air temperature were generally positive with respect to grassland carbon stocks.

What it means
In agreement with many results derived from empirical measurements, the model simulations suggest that the increasing CO2 content of the air will likely stimulate primary productivity in managed grasslands, thus leading to greater biomass production and enhanced carbon storage within their associated soils.  The significance of these findings can be better appreciated when it is realized that grasslands cover nearly 20% of the land surface of the globe and that they store at lest 10% of the soil organic matter of the planet.