USING MULTIPLE HIGH-RESOLUTION PROXY CLIMATE RECORDS TO RECONSTRUCT NATURAL CLIMATE VARIABILITY: AN EXAMPLE FROM THE CANADIAN ROCKIES
Mountain areas contain a variety of excellent natural archives that document former environmental changes with differing temporal and parameter resolution. These records involve both physical (e.g. glaciers, permafrost) and biological systems (e.g. trees) that respond to climate change and often occur in close juxtaposition, thereby providing complementary insights into former environmental changes. Since the time of Louis Agassiz, many key concepts about climate history have been developed from studies of the fluctuations of alpine glaciers (e.g. Penck and Bruckner, 1909; Matthes, 1939; Porter and Denton, 1967; Grove, 1987). Refining this history and supplementing it with new data, techniques and complementary sources (tree rings, lacustrine records, historical sources) allows us to document the magnitude and timing of past climate changes and benchmark natural climate variability at several timescales. Understanding and modelling this natural variability on decade-to-century timescales is a critical element in our ability to detect any anthropogenic signal in the relatively short instrumental climate record. It defines the background variability and trends upon which any future climate changes will be superimposed. Studies of historical system responses, particularly over the last century, also allow us to develop potential analogues to predict the future response of these systems.