Long term coastal monitoring along the Yukon Coast indicates acceleration of coastal retreat in the last 20 years

• Main Authors: Irrgang, Anna, Manson, Gavin K., Lantuit, Hugues, Overduin, Paul, Grosse, Guido, Günther, Frank
• Format: Conference Object
• Language: unknown
• Published: 2016
• Subjects: Arctic; Canada; Yukon; Ice; permafrost
• Online Access: https://epic.awi.de/id/eprint/42895/; https://epic.awi.de/id/eprint/42895/1/AMIrrgang_AGU_2016_epic.pdf; https://hdl.handle.net/10013/epic.49455; https://hdl.handle.net/10013/epic.49455.d001

It is accepted that the Arctic is warming, and may continue to warm, but the impacts on its coasts are not well documented. Permafrost coasts make up one third of the world’s coasts, though few studies quantify recent changes. Remote sensing allows the detection of patterns in regional coastal dynamics, and provides a quantitative evidence of average coastal change and trends in rates on decadal scales. We investigated a 230 km long coastal stretch along the ice-rich and thus erosion-sensitive Yukon coast in north-western Canada over the time period from 1951 to 2015. Georeferenced aerial photographs from the 1950’s, 1970’s and 1990’s as well as World View and GeoEye satellite imagery from 2011 were used to extract shoreline positions which were analyzed using the Digital Shoreline Analysis System (DSAS) extension for ESRI ArcGIS. To provide better temporal resolution of the shore dynamics over the last 20 years (1996-2015), seven coastal monitoring sites maintained by the Geological Survey of Canada were re-surveyed using real-time kinematic differential GPS. Remote sensing data analyses show that coastal retreat accelerated substantially between the 1990s to 2010s, to an average erosion rate of 1.3 m/a. In contrast, the temporally higher resolution ground survey data indicate that coastal erosion rates among the monitoring sites were stable or even showed a decelerating trend over the last 20 years. However, within the last three years, coastal retreat at three sites increased at an unprecedented rate, locally up to 9 m/a. Ground surveys and observations, with remote sensing data, indicate that the current rate of coastal retreat along the Yukon Coast is higher than at any recorded time.