Text by Lauri Laanisto
Wow, a 21-page Forum paper! The role of photosynthesis is global ecosystem and climatic models has been either oversimplified or plainly ignored, that is something I learned I think from the first meeting with Ülo. Of course the most emergent model to ignore photosynthesis (or at least mesophyll conductance) is the IPCC. If climate changes, then also the ecosystem processes that locally or regionally influence climate change will change, which is another pretty huge factor obstructing the predictability of climate change models. This viewpoint paper discusses seven different terrestrial biosphere models from the photosynthesis aspect. So, it´s a useful thing to read if you are using any of these models in your research.
Citation: Rogers, A., Medlyn, B. E., Dukes, J. S., Bonan, G., Caemmerer, S., Dietze, M. C., … Niinemets, Ü.,… & Prentice, I. C. (2017). A roadmap for improving the representation of photosynthesis in Earth system models. New Phytologist, 213(1), 22-42. (link to full text)
Accurate representation of photosynthesis in terrestrial biosphere models (TBMs) is essential for robust projections of global change. However, current representations vary markedly between TBMs, contributing uncertainty to projections of global carbon fluxes. Here we compared the representation of photosynthesis in seven TBMs by examining leaf and canopy level responses of photosynthetic CO2 assimilation (A) to key environmental variables: light, temperature, CO2 concentration, vapor pressure deficit and soil water content. We identified research areas where limited process knowledge prevents inclusion of physiological phenomena in current TBMs and research areas where data are urgently needed for model parameterization or evaluation. We provide a roadmap for new science needed to improve the representation of photosynthesis in the next generation of terrestrial biosphere and Earth system models.