Quantifying the Global Dynamics of Terrestrial Photosynthesis, 1900-2100

Quantifying, explaining, and predicting the temporal and spatial dynamics of photosynthesis from regional to global scales is important for understanding the potential impacts of rising atmospheric CO2 and changing climate on future plant production and the global carbon cycle. A new high-resolution modeling approach is described, tested, and applied. Photosynthesis is modeled using a detailed biochemical/biophysical algorithm, nested within a full treatment of the surface energy and hydrological balances. Canopy processes are parameterized at an intermediate level of detail. Photosynthetic capacity is either prescribed from remotely sensed data and plant-type specific properties, or simulated prognostically. A range of sensitivity tests are used to determine key processes in different regions and key areas for future research. Simulations of the distribution of plant production to the end of this century are performed using a range of global climate model predictions, and the implications for future nutrient demands, hydrological dynamics, and the global carbon cycle will be discussed.