Environmental Engineering Reference
In-Depth Information
FIGURE 4.23 Estimates of the contribution of glaciers and ice caps to global change in sea level equivalent
(SLE), in millimeters SLE per year. Source: Allison et al. (2009b).
land and Antarctica, can potentially contribute a total of approximately
0.7 m to global sea level, and they provide a source of freshwater in many
mountain regions worldwide (Bahr et al., 2009). For 1961-2003, glaciers
and ice caps contributed 0.5±0.2 mm y
-1
to global sea-level rise (Figure
4.22), increasing to 0.8±0.17 mm y
-1
for 1993-2003 (Allison et al., 2009b).
This new assessment (Figure 4.23) shows ice loss from glaciers and ice caps
slightly higher than those reported in IPCC AR4, contributing now about
1.2±0.2 mm y
-1
to global sea level rise. Glaciers and ice caps are not in
balance with the present climate; glaciers need to decrease in volume by
27% on average, and ice caps need to decrease by 26% to attain equilibrium
