## 2 Materials and Methods
### Remote Sensing and Spatial Data
Areas of dead ice covered by moraines were not included in the estimate of the glaciated area for any of the analysed periods. Estimates of area change within each zone and period are based on a spatial analysis. Since the number of observational records available is not comparable with the record of local climatic change, the mean ratio of retreat (km\({}^{2}\)/year) was calculated for each period in 50-m altitude intervals for each glacier (Table 1). The basis for the elevation was the DEM based on the 2007 survey. The DEM was corrected to the ice elevation state from 1979. In order to assess long-term trends in the fluctuation of glacier front positions within ASPA-128, our results were compared with changes in the Equilibrium-Line Altitude (ELA, Table 2), climate records (temperature and precipitation), and changes in the Positive Degree-Day sum (PDD) from the Bellingshausen, Jubany, and Ferraz stations on King George Island (Figures 1 and 2). In addition, we used archival photographs and maps to analyse the reduction in glacier surface elevation. Such data were available for the Baranowski and Ecology glaciers at elevations below 100 m a.s.l. (for example, Figures 4 and 5). The geomorphological mapping of glacier forefields that have become recently ice-free in ASPA-128 point toward landforms related to the surface melting of ice. Our initial field observations from ASPA-128 indicated slow glacier flow velocities. The glaciers were divided into individual drainage areas based on the analysis of the course of contours. Additional adjustments were possible from aerial photos from 1979 and 2011 based on crevasses distribution and orientation (Figure 5). Next, the glaciers were identified as either tidewater or land-terminating. This approach allowed us to take into consideration the unique behaviour of each glacier type and to illustrate individual glacier profiles (Figures 6 and 7). In the case of the graph shown on Figure 7, the area covered by glaciers was summed from the lower elevations upwards in 50-m altitude intervals. Only the selected Equilibrium-Line Altitude (ELA) heights are shown on this figure. The full list of the ELAs is presented in Table 2. Note that the study area extent did not allow for the measurement of the entire feeding area of some glaciers (for example, the Dera Icefall and Windy Glaciers). The tidewater glaciers in this study (Dera Icefall, Ecology, Baranowski and Windy glaciers) are typically large and are supplied directly from the Warszawa Icefield (300-400 m a.s.l. ; Figures 5 and 1). Parts of these glacier fronts terminate directly in Bransfield Strait, Admiralty Bay, or in shallow lagoons that are disconnected from the ocean during low tide. In 2011, these glaciers terminating in lagoons formed 10-30 m high ice cliffs that were unstable under tidal influences and, thus, experienced enhanced calving during austral summer. The land-terminating glaciers in this study (Thawing, The Tower, Sphinx, and small glaciers) branching from the Ecology Glacier (Xa, and Xb zone, Figure 5) are smaller and have zones of accumulation at lower elevations (200-350 m a.s.l.). Changes for each glacier zone were analysed in 50-m altitude intervals. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Glacier Mass Balance Year** & **ELA (m a.s.l.)** & **Reference** \\ \hline
1969/1970 & 140 & Orheim and Govoruhka 1982 [36] \\
1970/1971 & 170 & Orheim and Govoruhka 1982 [36] \\
1985/1986 & 150 & [PERSON] et al., 1995 [37] \\
1991/1992 & 160 & Braun and Rau 2000 [38] \\
1992/1993 & 200 & Braun and Rau 2000 [38] \\
1993/1994 & 200 & Braun and Rau 2000 [38] \\
1995/1996 & 200 & Braun and Rau 2000 [38] \\
1996/1997 & 250–270 & Braun and Rau 2000 [38] \\
1997/1998 & 180–200 & Braun and Rau 2000 [38] \\
1998/1999 & 200–220 & Braun and Rau 2000 [38] \\
2006/2007 & 290 & this study \\
2012/2013 & 156 & [PERSON] et al., 2015 [9] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The changes in the Equilibrium-Line Altitude (ELA) heights on King George Island.