Abstract:
Today, climate change is affecting virtually all terrestrial and nearshore environments, with effects that amplify a wide range of geologic hazards. This presentation will discuss ongoing and anticipated effects of a changing climate on landscape stability, focusing on threats to infrastructure and associated challenges of maintaining transportation corridors, utilities, water supply, and public safety. The growing problem of post-wildfire hazards provides an example of model applications for risk reduction. Scientific understanding of climate-exacerbated geohazards is growing rapidly, leading to substantial progress in protecting communities physically and financially, but major challenges remain.
Bio:
Amy East is a research geologist with the U.S. Geological Survey in Santa Cruz, California, where she studies Earth-surface processes related to climatic and anthropogenic disturbances. She holds a B.S. in geological sciences from Tufts University, a Ph.D. in geology and geophysics from MIT, a Professional Geologist license in California, and is a Fellow of the Geological Society of America.
Summary:
Landscape effects from climate change
Coastal retreat/inundation, sea level rise
Permafrost thaw
Thermal rock fracture
Slope failure
Erosion, sediment movement
Soil drying, drying, vegetation disturbance, drought
More extreme rainfall, precipitation shifts
Wind-blown dust, sand dune movement
Coastal effects due to sea level rises
Higher high-tides (sea level is 1 ft higher than 100 years ago)
Coastal property damage
Thermal effects
Permafrost normally is permanently frozen
When it partially thaws the waterlogged thawed soil destabilizes and flows off
Damage to buildings sited on permafrost, as well as linear infrastructure like pipelines
Landslide hazards
Many causes that weaken land
Trigger is usually water
Affect transportation, buildings
Can create compound hazards where a rockslide triggers extreme river flows that destroys dams and inundate settlements (e.g. Tibet rockslide)
Fires make landslides more likely to occur
Burned slopes are structurally weaker than land with active vegetation
Increased erosion, which can reduce water quality due to sediment deposition
Globally $215billion in physical assets exposed to wildfires in 2024/5
Droughts
Vegetation dies -> surface sediment becomes loose and airborne
Sand dunes cover roads and buildings
Airborne dust causes respiratory disease
Challenges in research
Limited time span of records makes it challenging to quantify these phenomena (~60 years)
Natural systems are noisy and stochastic
Many different dynamics are interacting
Makes it very difficult to localize the causes statistically (dust can be caused by vehicles or cattle)
Risk from climate change
Risk = probability of hazard * Exposure * Impact on Society
Quantifies society’s vulnerability to climate change
Key disruptions: Supply chains, water supplies, labor/productivity disruptions
Quantifications
Hazard awareness: simple categorization
Risk framework: quantifies every stage of the risk process, all the way to human impacts
Example: post-fire debris flows
Detailed USGS studies of post-fire landscape weakness
Estimated maps of debris flow probabilities across watersheds: based on rain flows along channels
Then estimate the downstream impacts of the debris flows: how far they may flow and what’s in the way (e.g. D-Claw: https://www.usgs.gov/software/d-claw-a-library-simulation-granular-fluid-flows-v100)
Sources of uncertainty:
Cross-regional transferability is challenging
Limited accuracy in soil structure data
Precipitation forecasts have limited precision
WEPP Model: https://www.nrcs.usda.gov/resources/tech-tools/water-erosion-prediction-project
Quantifies post-fire soil erosion without data on debris flows
Incorporates 3D topography, soil burn severity, land cover, hydrology and climate
WEPP applied to all of California and work is ongoing to scale WEPP to continental US
Success story: Blatten Switzerland
Landslide was forecasted ahead of time
Town was evacuated and 300 lives were saved
American Society of Civil Engineers has incorporated climate change risks
Flood load provisions (500 year flood plain, not 100 year)
Seal-level rise
NOAA’s Atlas 15 will incorporate extreme rainfall changes