December 8, 2017
Muller Ice Shelf (M) in 1989 and 2017 Landsat images fed by the Antevs (A) and Bruckner Glacier (B). The ice front is shown with yellow dots with separate calving margins on either side of Humphrey Island (H). The blue arrow indicates a developing rifted zone of melange ice. The pink arrows point out icebergs among sea ice.
Muller Ice Shelf is on the west side of the Antarctic Peninsula and is one of the smallest remaining ice shelves covering 40 km2 in 2007.
It is the northernmost ice shelf on the western side of the Peninsula and is fed by Bruckner Glacier (b) and Antevs Glacier (A), and is pinned on Humphreys Island (H). The glacier advanced from 1947 to 1956 with subsequent retreat until another advance period from 1974-1986 when the ice front advance led to a 4 square kilometer expansion Cook and Vaughan (2010). Retreat has since ensued Domack et al. (1995) suggesting that warm CDW that is currently within the fjord may be contributing to the rapid bottom melting and retreat of the ice-shelf in recent years. Here we use Landsat imagery to identify changes from 1989 to 2017.
In 1989 the western side of the ice shelf edge is near the north end of Humphrey Island and the east margin near a cape half along the eastern edge of Humphrey Island. By 2001 the western margin has retreated 1.5 km and the eastern margin 1.2 km. In 2016 the both the eastern and western margin have retreated to the southern end of Humphrey Island. The island still acts as a pinning point, but this connection is becoming tenuous. Of equal importance is the development of an area of substantial rifting north of the bluff on the southern margin of the ice shelf between Antevs and Bruckner Glacier at the blue arrow. In 2017 the rifting has further expanded, the ice melange now covering an area of ~1 square kilometer. From 1989 to 2017 the western margin has retreated 2.5 km and the eastern margin 1.5 km. The retreat due to calving is ongoing as indicated by the number of new icebergs in the Feb. 2017 image, pink arrows. Between this area of rifting and the decrease in connection to Humphrey Island the Muller Ice Shelf is poised for rapid disintegration like nearby Jones Ice Shelf. Bethan Davies provides a detailed look at the weaknesses of other Antarctic Peninsula ice shelves.
Muller Ice Shelf (M) in 2001and 2016 Landsat images fed by the Antevs (A) and Bruckner Glacier (B). The ice front is shown with yellow dots with separate calving margins on either side of Humphrey Island (H). The blue arrow indicates a developing rifted zone of ice weakness.
Google Earth image from 1998 and 2016 indicating rift development at blue arrow.
Figure 4.1 from Cook and Vaughan (2010) illustrating changes in ice shelf area.