Climate Indicators of Landslide Risks on Alaska National Park Road Corridors

Lader, Rick; Sousanes, Pamela; Bhatt, Uma; Walsh, John; Bieniek, Peter

Landslides along road corridors in Alaska national parks pose threats to public safety, visitor access, subsistence activities, and result in costly remediation of damaged infrastructure. Landslide risk in these areas, which contain near-surface permafrost, is associated with mean annual air temperatures (MAATs) above freezing and heavy precipitation events. Historical (1981-2020) ERA5 values of MAAT and summer precipitation (JJA PCPT) were compared to mid-century (2021-2060) and late-century (2061-2100) downscaled climate model projections across Gates of the Arctic National Park and Preserve (GAAR), Denali National Park and Preserve (DENA), and Wrangell-St. Elias National Park and Preserve (WRST). Observed trends of MAAT and JJA PCPT from 18 stations were compared with ERA5 trends to give context to the model projections. Road corridor values are given for the: proposed Ambler Road through GAAR, Denali Park Road in DENA, and McCarthy Road in WRST. ERA5 showed that all locations historically had MAAT values below freezing, but all three parks were warming significantly; similarly, all stations had below freezing MAATs, but all showed warming trends with 11 of the 18 being significant. Observed trends of JJA PCPT were mixed. Projections were considered to indicate elevated landslide risk when the projected MAAT exceeded freezing or the projected JJA PCPT value exceeded the ERA5 40-year maximum. Elevated MAAT risk was projected in the mid-century period for the Denali Park Road and McCarthy Road and across all three park road corridors in the late-century period; elevated JJA PCPT risk was projected in all periods for all road corridors with model variability.

Climate Indicators of Landslide Risks on Alaska National Park Road Corridors

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