Carbon-climate feedback: Interactions with nutrient cycles
Dr Yingping Wang, CSIRO Marine and Atmospheric Research

Presentation (2285kb)

We developed and implemented a land surface model into the CSIRO global climate model for studying carbon-climate interactions. Following the protocol of C4MIP Phase I experiment, we carried out two simulations involving integration of the global climate model forward from 1900 to 2000. One uses the prescribed sea surface temperature (SST), prescribed radiative forcing, CO₂ emissions from fossil fuel use, land use change and ocean and the land biosphere is driven with the observed global mean atmospheric CO₂ concentrations from 1900 to 2000 (simulation 1). The other uses the same prescribed fields from 1900 to 2000 except the global atmospheric CO₂ concentrations seen by the land biosphere after 1970 was kept constant at the level of 1970 (simulation 2). Results from simulation 1 show that the agreement is quite good between modeled and observed monthly mean surface CO₂ concentrations at most stations in the northern hemisphere, but rather poor in the southern hemisphere. The net ecosystem production from the global terrestrial biosphere changed from being slightly positive before 1950 (0.1±0.8 Gt C year^-1, or a carbon source), to being negative (-0.7 ±1.1 Gt C year^-1, or a carbon sink) after 1970. Differences in the predicted net ecosystem production of the global terrestrial biosphere between the two simulations suggest that CO₂ fertilization can explain a significant part of the decadal trend of CO₂ uptake after the 1970's. Variations of land surface temperature are significantly negatively correlated with the inter-annual variation of net ecosystem production from 1900 to 2000.

In collaboration with Australian Bureau of Meteorology and universities, we have imported the earth system model from UK Meteorological Office to study the interactions of terrestrial and marine carbon cycles and global climate in the earth system. In this talk, I shall outline the major tasks and scientific questions we shall address within the next three to five years.

Dr Yingping Wang received his PhD in Plant Physiology from Edinburgh University, UK in 1988. He has been a research scientist with CSIRO since 1990. He currently is the leader of land surface modelling team in ACCESS. His interests include terrestrial ecosystem modelling, sources and sinks of greenhouse gases, application of model data fusion in terrestrial ecosystem modelling.