Frequency-dependent landscape response to climatic forcing

Abstract : Whereas the existence of pronounced orbitally controlled periodicities is a major feature of Earth climate, its impact on landscape dynamics remains poorly understood. We use a Landscape Evolution Model (LEM) to systematically investigate the response of landscapes to a range of periodic oscillations in precipitation. The resulting sediment-flux evolution displays a pronounced sensitivity to the period of the input precipitation signal, such that, for a given erodibility, a specific periodicity maximizes the amplitude of the response. This optimal period of “resonance” scales as the inverse of the erodibility, but is progressively filtered out of the response when the intensity of hillslope diffusion increases. This frequency-dependent landscape behavior displayed by our model provides a mechanistic perspective on Molnar's (2004) proposition that ubiquitous changes in Late Cenozoic continental denudation could result directly from modifications in the spectral content of the climatic signal.