Earth system models: a test using the mid-Holocene in the Southern Hemisphere

Abstract

Palaeoclimatic reconstructions from proxy data have been compared with climate model outcomes for three decades. It has become evident that explanations of past climates can rely on neither data source alone, the former often being descriptive tools and the latter dependent on model structures and parameterisations. The status of vegetation changes, either as a follower of climate changes or as a modulator of insolation-terrestrial system responses, is vital if proxy records are to be effectively interpreted in climate terms and if models are to be more robust in appropriately incorporating vegetation roles. We use an earth system model (CLIMBER) and proxy data from Southern Hemisphere locations to compare postdictions of mid-Holocene climates. It is concluded that climate simulations and predictions are likely to be inaccurate if vegetation is not properly incorporated, and appropriate models can allow hypotheses to be developed that better explain atmosphere-earth system linkages.