Ice loss from ice sheets 2: Antarctica ice sheet

Hope you have enjoyed your Christmas holidays!


Following last post, we are going to look at Antarctica ice sheet.  About 90% of ice on the Earth, which is the largest potential contributor to sea level rise in the future. Antarctica ice sheet consists of three parts, West Antarctica, East Antarctica and the Antarctica Peninsula. Figure 1 show a schematic structure of Antarctica.


Observations and scientific understanding of Antarctica remain at low level (IPCC, 2013), which cause poor understanding of ice loss at Antarctica ice sheet. Overall, ice has kept losing over the last two decades though with large uncertainty, as showed in figure 2. The loss rate had increased from -135 to -58 Gt/yr during 1993-2010 to -221 to -74 Gt/yr during 2005-2010 (IPCC, 2013). The loss was caused by warming in temperature, as well as warming in tropical sea surface temperature (Ding et al., 2011). Shepherd et al. (2012) found that ice loss occurred at the Antarctica Peninsula and the West Antarctica with accelerating rate, while the East Antarctica had net gain ice. The three maps in lower Figure 3 show these changes in ice. 


Figure 1. Cross section of Antarctica ice sheet. (source: LIMA, NASA)



Figure 2. Cumulative ice loss from Antarctica ice sheet. (Source:IPCC, 2013)






Figure 3. Ice loss rate (Source: IPCC, 2013)


However, a relative new study by NASA indicated that Antarctica ice sheet gains more ice than losses. Though this study agreed with IPCC (2013) and Shepherd et al. (2012) that
ice loss occurred at the Antarctica Peninsula with accelerating rate, it showed that
East Antarctica and the interior of West Antarctica had net gain of ice with thicker at the rate of 1.7 cm/yr, compensating ice discharge over the whole ice sheet and even reducing sea level rise at the rate of -0.23 mm/yr. This challenges the statement that Antarctica ice sheet currently contributes to sea level rise at the rate of 0.27 ±0.11 mm/yr over 1993-2010 and 0.41 ±0.20 mm/yr over 2005-2010 (IPCC, 2013). Future studies are required here in order to solve the accurate contribution of Antarctica ice sheet on sea level rise.

Figure 4. Changes in ice by NASA's study.