Toward a Realistic Estimate of Sea-Level Rise and Global Water Balance Due to Glacier Wastage

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The potential environmental, social, and economic impacts of rising sea levels are serious. A major potential source of water to the world's oceans that would result in sea-level rise is from melting of the world's glaciers. This research project will examine the contributions of meltwater from all of the world's glaciers except the Antarctic and Greenland ice sheets in the recent past and potential contributions in the future. The investigators will model results from mass-balance time series for different glaciers to the middle of the 20th century using observational data, repeated geodetic and mapping surveys, and aerial photographs. Statistical analyses will help determine teleconnections in glacier volume change between glaciated regions and relate these to teleconnections in climate. Static sensitivities of glacier mass balances to air temperature and precipitation change will be calculated using long-term records and glaciological data averaged by mountain ranges. Stochastic scaling and percolation theory will be used to estimate the number and size of glaciers and relationships among glacier area, volume, and response times. Expected outcomes of the project include greatly improved information and understanding of changes in glacier volume, which affect sea level and the global water balance, improved information on large-scale patterns of climate, and evidence of climate change as revealed by glaciers. Project results will be used by several world meteorological programs, including the Global Climate Observation System (GCOS), and also the United Nations Environmental Program (UNEP), Global Environmental Monitoring System (GEMS), World Glacier Monitoring Service (WGMS), and the National Snow and Ice Data Center in Boulder.There are significant social and economic reasons for improving capabilities to project future sea-level rise. A major fraction of the world's population and the world's most valuable real estate are at elevations within a few meters of sea level. Local effects like reductions in the sediment discharge of large rivers and subsidence caused by pumping water or oil out of the ground are exacerbated by sea-level rise. Improved estimates of sea-level rise based on better understandings of the contributions of melting glaciers to global ocean volume therefore will be important for land-use planning, coastal-zone management, and other social, political, and economic processes that are at risk. This study will produce a greatly improved estimate of changes in glacier ice volume which affects sea level and the water balance between land and ocean; significant new information on regional and temporal patterns of glacier-climate interactions, and algorithms for extending these results in studies of climate and glaciers in the past; regional information on changes in runoff to be expected as a result of global warming in those areas where the runoff is largely derived from glacier wastage, such as closed drainage basins in South America and Central Asia; improved information on large-scale patterns of climate and climate change as revealed by glaciers, and new scientific advances on the mathematical treatment of incomplete data sets.