Journal Article

Evaluating the Land and Ocean Components of the Global Carbon Cycle in the CMIP5 Earth System Models

Anav, A., Ciais, P., Zhu, Z., Cox, P., Friedlingstein, P., Myneni, R., Kidston, M., Jones, C., Jung, M., Bopp, L.

2013

Overview

The authors assess the ability of 18 Earth system models to simulate the land and ocean carbon cycle for the present climate. These models will be used in the next Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) for climate projections, and such evaluation allows identification of the strengths and weaknesses of individual coupled carbon–climate models as well as identification of systematic biases of the models. Results show that models correctly reproduce the main climatic variables controlling the spatial and temporal characteristics of the carbon cycle. The seasonal evolution of the variables under examination is well captured. However, weaknesses appear when reproducing specific fields: in particular, considering the land carbon cycle, a general overestimation of photosynthesis and leaf area index is found for most of the models, while the ocean evaluation shows that quite a few models underestimate the primary production. The authors also propose climate and carbon cycle performance metrics in order to assess whether there is a set of consistently better models for reproducing the carbon cycle. Averaged seasonal cycles and probability density functions (PDFs) calculated from model simulations are compared with the corresponding seasonal cycles and PDFs from different observed datasets. Although the metrics used in this study allow identification of somemodels as better or worse than the average, the ranking of this study is partially subjective because of the choice of the variables under examination and also can be sensitive to the choice of reference data. In addition, it was found that the model performances show significant regional variations.

• Publisher: American Meteorological Society
• Subject: 20th century / Aerosols / Atmospheric models / Biogeochemistry / Carbon / Carbon cycle / Carbon dioxide / Climate / Climate change / Climate cycles / Climate models / Climatology / Climatology. Bioclimatology. Climate change / Computer simulation / Datasets / Earth / Earth Sciences / Earth, ocean, space / Exact sciences and technology / Experiments / External geophysics / General circulation models / Geophysics. Techniques, methods, instrumentation and models / Global climate models / Greenhouse gases / Identification / Intergovernmental Panel on Climate Change / Land / Leaf area / Leaf area index / Mathematical models / Meteorology / Modeling / Modelling / Ocean models / Oceans / Performance measurement / Photosynthesis / Primary production / Probability density functions / Probability theory / Regional variations / Sciences of the Universe / Seasonal variation / Simulation / Simulations / SPECIAL C4MIP COLLECTION / Variables