population expansions, cultural mores, climate, disease and warfare in changing human attitudes and responses through time. This is especially the case if the past is to be used in more sophisticated ways than as a simplistic analogue of projected future conditions. We also know that assessment of the sensitivity or vulnerability of modern landscapes and ecosystems to future human activities and climate can be greatly improved by knowing the rates and directions of past trajectories in key processes such as land cover, soil erosion and flooding, observing how thresholds have been transgressed and deducing the natural or pre-impact patterns of environmental variability. Already, such knowledge is leading to the improved formulation of resource management strategies.
The present nature and complexity of socio-ecological systems are heavily contingent on the past; we cannot fully appreciate the present condition without going back decades, centuries or even millennia. As we are witnessing today with global warming, current societal actions may reverberate, in climatic and many other ways, for centuries into the future. As such, there is the real danger that our visions of the future are becoming unconstrained by knowledge of what has already occurred, at least in part because information about human-environment interactions in the historical past has not been well organized for this purpose or properly utilized. If we continue to operate in ignorance or denial of this integrated historical understanding, we run the very real risk of mirroring the paths of the Easter Islanders, the Classic Maya or the Roman Empire. But if we can adequately learn from our integrated history, we can create a sustainable and desirable future for our species.