# Automatically Extracted Antarctic Coastline Using Remotely-Sensed Data: An Update
## 4 Results and Analysis
### Changes of Coastline in the Regions Around Six Ice Shelves
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Area Change of Ice Shelves (km\({}^{2}\))**} \\ \hline
**Period** & **WIS** & **RSIS** & **AIS** & **RIS** & **MGT** & **PIS** \\ \hline
2005–2010 & \(-\)4836 & 2971 & 698 & 2395 & \(-\)2582 & \(-\)852 \\
2010–2017 & \(-\)1900 & 3057 & 2124 & 3887 & \(-\)67 & 3174 \\
2005–2017 & \(-\)6736 & 6028 & 2822 & 6282 & \(-\)2649 & 2322 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Deviation of coastline area in each sector (km\({}^{2}\)) during three intervals. across the PIS continued during the 2010-2017 period, with and expansion totaling 3490 km\({}^{2}\) in some parts, and a loss of 516 km\({}^{2}\) due to calving in other parts of the PIS. Besides widespread local ice breakup events, some ice shelves have also undergone the reverse process (i.e., expansion), mainly in the more stable and wider East Antarctica ice sheet, such as the Amery Ice shelf. In the following, we calculate the expanded area and present an analysis of these expansion ice shelves. The AIS is located at the head of the Prydz Bay in East Antarctica, with an area of approximately 60,000 km\({}^{2}\)[34]. It is the third largest ice shelf in Antarctica, after the Ross Ice Shelf and the Filchner-Ronne Ice Shelf [35]. Between late 1963 and early 1964, a large piece of the ice shelf, about 9600 km\({}^{2}\), calved and drifted to the west [36]. The calving front proceeded equator-ward from 2005 to 2017. In our results, there is a growing pattern shown in the area change, especially in the Prydz Bay. As shown in Table 6, the AIS increased by 698 km\({}^{2}\) from 2005 to 2010 at a rate of +139.6 km\({}^{2}\)/year. It increased again by 2124 km\({}^{2}\) from 2010 to 2017 at a rate of +303.4 km\({}^{2}\) /year. The net rate is +235.2 km\({}^{2}\)/year. The RSIS is the largest ice shelf in the Antarctica with an approximate area of 500,809 km\({}^{2}\) in 2013 [37]. It is an important gateway through which signals of climate change approach West Antarctica. Based on coastline extraction results in this study, the coastline area increased by 2971 km\({}^{2}\) from 2005 to 2010 at a rate of +594.2 km\({}^{2}\)/year, and increased by 3057 km\({}^{2}\) from 2010 to 2017 at a rate of +436.7 km\({}^{2}\)/year. The net increase is 6028 km\({}^{2}\) at a net rate of +502.3 km\({}^{2}\)/year. According to [31], between 2005 and 2017, observed sea-ice concentration increased and sea surface temperature (SST) decreased with maximum trends near the sea-ice margin (where ice expansion is likely to occur), in particular north of the RSIS. The RIS is bounded on the west by the base of the Antarctic Peninsula. Although it has had several events of calving, the extracted coastlines still show a net expanding pattern from 2005 to 2017. In a previous study on the ice velocity changes in the Ronne Ice Shelf [38], it was concluded that the Ross and Filchner Ice Shelves exhibited signs of pre-calving events, representing the largest observed changes, with an increase in speed in excess of +100 m/year in 12 years. As shown in Table 6, the area increased by 2395 km\({}^{2}\) from 2005 to 2010 at a rate of +479 km\({}^{2}\)/year. There is a much more obvious trend of coastline expansion from 2010 to 2017, when the area increased by 3887 km\({}^{2}\) at a rate of +555.3 km\({}^{2}\)/year. The net rate is +523.5 km\({}^{2}\)/year. Based on the area change of the RIS and the RSIS, we noticed that the expansion of ice sheet could impact on the shape of these shelves. These two shelves have advanced, but there is not much protrusion into the ocean. For the RIS and the RSIS, the longest linear distance between the corresponding points from the coastline in 2005 and in 2017 was 16.28 km and 14.17 km, respectively. On the other hand, we found that when the shelf protrudes deeply into the ocean it would likely become mechanically unstable, such as the calving of Larsen-B in 2002.