Geomorphic response to Late Holocene climate variation and anthropogenic pressure, northeastern Prince Edward Island, Canada

Abstract

Geomorphic response provides an index to climate change and variability. Differing time scales of both weather/climate events and landform response complicate interpretation. Anthropogenic modification, particularly in coastal and aeolian dune environments, represents a further geomorphic influence. Northeastern Prince Edward Island (PEI), Canada, is a marine-dominated environment subjected to rising sea level throughout the late Holocene. The combination of rising sea levels, increased anthropogenic utilization of the coast for residential, and tourism purposes, and limited offshore winter ice conditions have resulted in accelerated erosion and degradation of the dunes and coastline. The aeolian succession indicates that temporal and spatial transitions from isolated shield dunes to parabolic dunes to linked coastal transverse dune complexes are characteristic of the coastal dune fields. Sand supply is the most significant control on dune morphology, development, and extent. Superimposed dome dunes and shield dunes are prevalent in areas of anthropogenic disturbance. Dune migration along the coastal zone has varied considerably, with rates locally in excess of 10m/a over short times. Winters marked by relatively limited sea ice and scarce snow cover, resulting from more temperate winter conditions, allow increased erosion by strong storms. Deflation of dune crests and development of blowouts is notably accentuated along human trails. The climate variations recorded in Atlantic Canada over the past decade fall within the range of those recorded previously within the twentieth century, and thus do not indicate conclusive evidence of a pronounced trend of climate change in this region. However, analysis of northeastern PEI demonstrates that dune coastlines can evolve rapidly in response to short-term and intermediate-term climate variation, particularly when coupled with anthropogenic pressure. Similar geomorphic effects in combination with climate variation and storm activity should be anticipated along other dune coastlines that have been subjected to intense anthropogenic utilization during earlier periods of the Quaternary.