# Landscape Response to Climate Change

**Problem and Objectives:** The onset of rapid changes in temperature,
precipitation, and seasonality and intensity of storms as a result of
global climate change is certain to cause landscape responses, such as
increased flooding from more intense storms, changes in sediment
delivery to basins, and changes in water resources as a result of
changes in mean climate. These issues must be addressed on local to
National levels. USGS is uniquely positioned to evaluate the suite of
landscape responses, from hydrologic to geomorphic to ecologic, and
their interwoven effects. Moreover, USGS is positioned to anticipate
landscape responses by two primary methods:

1.  Evaluate and develop paleorecords for climatic events of specific
    periods of the last few millennia, such as the Medieval Warm Period
    (\~1,000 AD), which may inform on landscape response to future
    warmer climates. For instance, archives of seeds and pollen,
    isotopic signals for many minerals including opal, calcite, and
    clays (as well as tree rings), and sediment characteristics all
    carry information on the past ecology, hydrology, and geology of an
    area.

2.  Develop predictive models based on mechanistic and empirical
    understandings of plants, hillslope behavior, sediment transport
    mechanisms, flood behavior, and the routes and the fate of
    sediments.

The development of predictive maps based on an integrated science
approach that couples paleoclimate, detailed geochronology and
geomorphology across paired landscapes is a particularly appealing
method because it will allow us to piece together the links between
landscape changes and climate in tandem, rather than focusing on
individual locations as separate entities.

**Strategy**: GD has much of the expertise needed for this research
within several programs, but coalescing and fostering the appropriate
talent within GD and across Discipline lines will accelerate this
activity. At the regional level, the approach would be to tackle paired
sites that address climate and landscape gradients or boundaries, e.g.,
sites on west and east sides of prominent mountain belts such as the
Rockies or Sierra; sites in warm and cold deserts; sites with
winter-dominated precipitation vs. summer monsoon precipitation. Sites
would be selected based on degree of expected climate impacts, degree to
which results could be extrapolated widely, and the depth of existing
knowledge that can jump-start the studies.

On the geology side of the topic, the most pressing needs are for higher
resolution paleoclimate records of the past few millennia, improved
climate proxy information, and improved understanding of hillslope
sediment storage. Improving these data using, for example, new isotopic
investigations into climate proxies in soils, LiDAR for hillslopes,
etc., brings promise of greatly improving the ability to hindcast and
forecast geomorphic response.

**An example**. Recent studies suggest that southwest deserts may be
more impacted by intense summer monsoons and tropical storms in the
future as a result of nearby tropical oceans warming and that similar
climate conditions a few millennia ago caused widespread alluvial fan
aggradation. We could develop higher resolution paleo-records to improve
this prediction, including pairing marine and terrestrial records to
confirm or deny the causality implied. We could evaluate hydrologic,
geomorphic, and ecologic response on various time and spatial scales. We
could evaluate the potential for similar occurrences in the near future,
such as sufficiency of hillslope storage to drive alluvial fan
aggradation. Communities and infrastructure in the vulnerable locations
could be warned to plan for sedimentation in future floods.

**Impact**. Landscape forecasts will help prepare communities for
upcoming changes as well as help federal and state agencies plan for
changes on Federal lands and changes potentially impacting critical
infrastructure. These future scenarios must be dovetailed with
comparable studies of other landscape-scale processes, e.g., effects of
changes in land-use, invasive species, and changes in fire regime, to
produce more comprehensive forecasts of landscape response.

**Partnerships**. Several large-scope studies are underway, such as the
NSF observatories (NEON, Hydrologic Observatories, geomorphology
consortia, Critical Zone Observatories (CZO)); studies within the
broader climate community (NOAA, academia), LTERs, and research groups
in BLM, NPS, USFS, ARS.

*Dave Miller (<dmiller@usgs.gov>)*