Improving Our Understanding of Earth System Processes: GREENCYCLES Annual Network and Midterm Review Meeting, Barcelona, Spain, 21–23 March 2007

The latest Intergovernmental Panel on Climate Change report documents numerous examples of how human activities are profoundly affecting our global environment with long‐term consequences for the climate system. However, considerable uncertainty remains concerning future Earth system responses and likely impacts on the sustainability of life on Earth under the threat of changing climate. The International Geosphere‐Biosphere Programme recognizes that understanding and quantifying the complex interactions between the biosphere and the climate system are essential for assessing potential sustainable futures. Major limits to our current understanding of biosphere‐climate feedbacks result from (1) a lack of observations on biosphere‐atmosphere fluxes of important radiatively active gases and aerosols; (2) insufficient mechanistic understanding of the processes driving these exchanges over different temporal and spatial scales; (3) a lack of Earth system models adequately constrained to predict these exchanges as a function of environmental change; and (4) a lack of integration between scientific disciplines and research centers.