Running before we can walk

'Ecological certainty' is not a phrase one often hears, primarily because ecosystems are complex and diverse. As a consequence, terrestrial carbon cycle models exhibit huge uncertainty in future projections. In an effort to represent ecosystem processes more faithfully, terrestrial carbon cycle models are becoming more complex, however, the contribution of added model complexity to model uncertainty is seldom thoroughly evaluated. Improved predictive certainty requires that modellers and experimentalists work together to fully evaluate multiple competing assumptions during model development, focusing on the greatest sources of global carbon cycle uncertainty.