Abstract
Environmental impact assessments for new Arctic infrastructure do not adequately consider the likely long-term cumulative effects of climate change and infrastructure to landforms and vegetation in areas with ice-rich permafrost, due in part to lack of long-term environmental studies that monitor changes after the infrastructure is built. This case study examines long-term (1949–2020) climate- and road-related changes in a network of ice-wedge polygons, Prudhoe Bay Oilfield, Alaska. We studied four trajectories of change along a heavily traveled road and a relatively remote site. During 20 years prior to the oilfield development, the climate and landscapes changed very little. During 50 years after development, climate-related changes included increased numbers of thermokarst ponds, changes to ice-wedge-polygon morphology, snow distribution, thaw depths, dominant vegetation types, and shrub abundance. Road dust strongly affected plant-community structure and composition, particularly small forbs, mosses, and lichens. Flooding increased permafrost degradation, polygon center-trough elevation contrasts, and vegetation productivity. It was not possible to isolate infrastructure impacts from climate impacts, but the combined datasets provide unique insights into the rate and extent of ecological disturbances associated with infrastructure-affected landscapes under decades of climate warming. We conclude with recommendations for future cumulative impact assessments in areas with ice-rich permafrost.
Highlights
Most roads and most permanent infrastructure in northern Alaska are built on thick gravel pads (Ferrians et al 1969)
Thermokarst refers to the process by which thawing of icerich permafrost or melting of massive ground ice creates subsidence of the ground surface and irregular topography consisting of characteristic landforms, such as thermokarst pits, ponds, lakes, mounds, and high-centered polygons (Fig. 1) (Jones et al 2013; Kanevskiy et al 2022)
We present the results from each method, discuss changes to landforms and vegetation in each trajectory of change, and conclude with recommendations for future Cumulative impact assessments (CIAs) for roads and related infrastructure in ice-rich permafrost landscapes
Summary
Most roads and most permanent infrastructure in northern Alaska are built on thick gravel pads (Ferrians et al 1969). The pads are needed to protect structures from thermokarst and thermal erosion of the permafrost beneath them, but they alter the hydrology and snow patterns, add large volumes of dust to adjacent ecosystems, and promote a variety of other roadside impacts that cause complex cumulative impacts to the underlying permafrost and adjacent ecosystems These impacts have been studied separately to some extent in previous studies of road-related impacts in northern Alaska (e.g., Benson et al 1975; Everett and Parkinson 1977; Brown and Berg 1980; Everett 1980a;Auerbach et al 1997; Kidd et al 2006; Myers-Smith et al 2006; Gill et al 2014; Walker and Peirce 2015; Raynolds et al 2014a, 2020; Ackerman and Finley 2019; Connor et al 2020; Schneider von Deimling et al 2021; Kanevskiy et al 2022). Efforts are being made to develop engineering solutions to reduce the impacts to infrastructure (e.g., Schneider von Deimling et al 2021), but the long-term cumulative impacts of road-related and climaterelated impacts to permafrost, landforms, and vegetation in adjacent Arctic ecosystems remain poorly studied and are not adequately considered during the planning process for new roads
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