But still simplistic.

To date, climate models ignored the nutrient requirements for new vegetation growth, assuming that all plants on earth had access to as much "plant food" as they needed. But by taking the natural demand for nutrients into account, the authors have shown that the stimulation of plant growth over the coming century may be two to three times smaller than previously predicted. Since less growth implies less CO2 absorbed by vegetation, the CO2 concentrations in the atmosphere are expected to increase.

However, this reduction in growth is partially offset by another effect on the nitrogen cycle: an increase in the availability of nutrients resulting from an accelerated rate of decomposition – the rotting of dead plants and other organic matter – that occurs with a rise in temperature.

Combining these two effects, the authors discovered that the increased availability of nutrients from more rapid decomposition did not counterbalance the reduced level of plant growth calculated by natural nutrient limitations; therefore less new growth and higher atmospheric CO¬2 concentrations are expected. . .

"The biggest challenge has been bridging this multidisciplinary gap and demonstrating to the very broad range of climate scientists who range everywhere from cloud dynamicists to deep ocean circulation specialists that [incorporating the nitrogen cycle] is a worthwhile and useful approach." . .

This breakthrough is one more step toward a more realistic prediction for the future of the earth's climate. Nevertheless, potentially significant processes and dynamics are still missing from the simulations. Thornton also stresses the importance of long-term observation so scientists can better understand and model these processes. . .

Other shortcomings of climate simulations include the disregard of changing vegetation patterns due to human land use and potential shifts in types of vegetation that might occur under a changing climate, although both topics are the focus of ongoing studies.

It takes more than nitrogen to grow plants, and all of that "rotting of dead plants" is actually a population explosion of microorganisms. Model that.