Mass Balance Estimates of Global Mountain Glaciers and Ice Caps
Shum, C.K.¹; Braun, Alexander²; Cogley, Graham³; Duan, Jianbin¹; Guo, Junyi¹; Huang, Zhenwei¹; Howat, Ian⁴; Kuo, Chungyen⁵; Lee, Hyongki⁶; Tseng, Steven Kuo-Hsin¹; Wan, Junkun¹; Yi, Yuchan¹; Ding, Xiaoli^7
1Ohio State University/School of Earth Sciences, UNITED STATES; ²University of Texas at Dallas/Dept. of Geosciences, UNITED STATES; ³Trent University/Department of Geography, CANADA; ⁴Ohio State University/Byrd Polar Research Center, UNITED STATES; ⁵National Cheng Kung University/Dept. of Geomatics, TAIWAN; ⁶University of Houston/Dept. of Civil & Environmental Engineering, UNITED STATES; ⁷Hong Kong Polytechnic Univ, HONG KONG

The 2007 Intergovernmental Panel for Climate Change (IPCC) Fourth Assessment Report (AR4) narrowed the gap between the observed sea-level rise and various geophysical causes of sea-level rise as compared to the 2001 IPCC Third Assessment Report. Since then, post-IPCC AR4 assessment studies indicate a significantly higher sea-level budget discrepancy: circa 50-70% of the observed sea-level rise of ~2 mm/yr remains unexplained. Although the pre-AR5 literatures seem to have indicated reconciliation of various published estimates, we find that the sea-level budget closure remains elusive. The current sea-level budget discrepancy is primarily attributable to the wide range estimates of sea-level contributions from rapidly ablating mountain glaciers and ice-sheets. In particular, the Himalayan glacier system, as part of the Asian High Mountain glacier systems remains a focus of public and scientific debate, as the uncertainty of its mass balance estimates and its future projection have a significant implication of water resource problems potentially affecting 5 billion people, or ~43% of the world's population in the region. Here we provide results of a study comparing various geodetic measurement techniques with distinct accuracy, limitations and varying spatial resolutions, with in situ data, towards the goal of improved quantification of the global mountain glacier and ice cap mass balance.