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Feedbacks and Linkages between Climate and Surface Processes with Mountain
Building and Decay
The rugged topography of mountain environments reflects the interplay of
spatially variable tectonic uplift and erosion. The consequences of rapid erosion in
response to snowmelt, intense rainfall, or glacial dam-break floods are familiar to
those living in mountain environments. Less widely appreciated is how rates and
patterns of deformation in tectonically active mountain belts can be greatly influenced
by the spatial distribution and pace of erosion by landslides, river incision, and
glaciation (NRC, 2010a). Recent recognition of the strong coupling between erosion
and surficial mass redistribution and deeper tectonic and structural deformation
creates new opportunities for interdisciplinary research that bridge climate science,
geomorphology, structural geology, and geophysics.
Precipitation and erosion induced by orogenic effects impact the distribution
of deformation in mountain belts. Conversely, the size and distribution of high-
elevation topography influence global, regional, and local climates (e.g., Meehl,
1992; Wu et al., 2007). While much of the work on climate-erosion linkages in the
past decade has focused on steady-state landscapes, new research opportunities in
transient responses of landscapes include the buildup and tearing down of mountains,
the evolution of rift zones or volcanic arcs, and the role of climate variability (ranging
in scale from glacial-interglacial periods to surface response to changes in storm
frequency-magnitude relationships). The response of crustal-scale processes and
feedback through climate linkages is central to understanding the controls on
mountain building and decay and landscape response times to climatic changes and
climate variability.
Erosional unloading and sediment loading of Earth's surface also influences
the structural geology and rheology of the lower crust. While coupled tectonic-surface
process models predict that the structural evolution of a mountain belt is sensitive to
spatial and temporal variability in climate forcing (see Figure 2.16), the common
assumptions that erosional efficiency increases linearly with precipitation, discharge,
or stream power have not been demonstrated over orogenic timescales. Similarly, the
role of lithological variability on long-term patterns of landscape evolution remains
poorly constrained.
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