HOW ARE SEDIMENTARY AND GEOMORPHIC PROCESSES IN THE WESTERN U.S. RESPONDING TO MODERN CLIMATE CHANGE? (Invited Presentation)

Many studies have modeled potential landscape response to future climate, but thus far there has been no comprehensive evaluation of responses to recent, modern climate change that are already evident from field and remote-sensing data. Focusing on the western U.S., a region with generally steep relief and high sediment yield likely to be sensitive to climatic forcing, we review and synthesize current knowledge of sedimentary and geomorphic response to modern climate change. We test four hypotheses: that over the past 50 years new climate-driven changes will be detectable in (1) watershed sediment yields; (2) slope stability; (3) fluvial channel morphology; and (4) aeolian sediment mobility in drylands. We examine the extent to which these hypotheses are currently testable given the state of available data, natural autogenic and stochastic variability in earth-surface processes, and the human overprint on many western U.S. landscapes. Given the present availability of data with which these hypotheses can be tested relative to gaps in knowledge, we consider ways in which the earth-science community can make progress over the next several decades in understanding and resolving the responses of modern landscapes to recent and ongoing climate change.