News & Events

Noon seminar - Modeling Arctic coastal erosion

Monday, March 14, 2011, 12:00PM - 1:00PM

Speaker

Irina Overeem

INSTAAR

Location:

ARC 620

The extent of Arctic sea ice has been shrinking rapidly over the past few decades, and concurrent acceleration of erosion is now occurring along the Arctic coast. This both brings coastal infrastructure into harm’s way and promotes a complex response of the adjacent landscape to global change. We here quantify the effects of declining sea ice extent on coastal erosion rates along a 75-km stretch of permafrost coast along the Beaufort Sea, Alaska, where present-day erosion rates are ~14 m yr-1. Observations suggest thermal erosion controls the notching of the base of the 3-5m tall bluffs and subsequent bluff failure. We used a modified iceberg-melting algorithm to further investigate the erosion process.

To look at long-term changes we model the interaction between the nearshore sea ice concentration, the location of the sea ice margin, and the fetch-limited, shallow water wave field, since these parameters ultimately control both sea surface temperatures and the height to which these waters can bathe the frozen bluffs. Thirty years of satellite passive microwave data reveal that the nearshore open water season lengthened ~54 days over 1979-2009. Given these time series, we modeled daily wave heights during the open water season for each year. This “annual wave exposure” increased by 250% during 1979-2009. Ultimately, we aim to couple and employ these models to explore changes in coastal retreat rates for various climate change scenarios that include further increase in the duration of sea-ice free conditions, warming ocean temperatures, and changes in storm frequencies.