The rationale being that if photosynthesis increases, so should biomass and therefore also rates of respiration and decompostion. One result from their investigation can be seen above in the Graph output from the model. The model indicates that with increasing atmospheric CO2 and a proportional increasing uptake of CO2 by the biosphere, there is no indication, after a century, that a new equilibrium will soon be established. The feedback incorporated into the the model can account for a reduction in the impact of fossil fuel emissions on rising atmospheric CO2, but not bring it to an equilibrium within the next century. Photosynthesis would not be expected to increase in all parts of the biosphere, but rather only in areas where CO2 is the prime limiting factor.
Recent evidence points to a significant sink in the eastern North American decidous forest.
Diffusion into the oceans may also play a significant role. This inquiry resulted in students attaining a much higher level of intimacy with the global carbon cycle and the possible effects of altering it. Also, they are able to take real advantage of the computational power of the computer. The activity promotes attention to common themes as emphasized in systems thinking, the AAAS National Benchmarks and the Maryland Core Learning Goals. Students are mindful of the limitations of the model and the assumptions which were built into it.