Ice Sheet Mass Changes and Contribution to Sea Level Rise  Greenland and Antarctic ice sheets were close to balance 1992 to  Net only 1% of annual mass input (-19 Gt/yr; mm/yr sea level rise).  Reduces uncertainty in IPCC estimates and provides baseline for ICESat.  Greenland was growing inland & thinning at margins. West Antarctica was thinning and East Antarctica was thickening.  Antarctic ice shelves: losing -95 Gt/yr in West, gaining 142 Gt/yr in East  Paper by Zwally et al. accepted J. Glaciology (2005, in press).  Based on ERS-1,2 radar altimeter data (& ATM on Greenland margins). (+10.8 ± 2.5 Gt/yr; mm/yr sea level) (-46.5 ± 4.4 Gt/yr; mm/yr sea level). (+16.5 ± 10.7 Gt/yr; mm/yr sea level) (1 Gt = 1Km 3) Jay Zwally, Cryospheric Sciences Branch, Hydrospheric & Biospheric Sciences Laboratory

Global Carbon Cycle: Recent Progress Toward a Bicarbonate Ion Raman LIDAR Frank Hoge, Wallops Flight Facility, Hydrospheric & Biospheric Sciences Laboratory, Ocean Sciences Branch The goal of this research is to develop airborne LIDAR technology to remotely sense the massive (~97%) global oceanic inorganic carbon pool (to complement the ~3% organic carbon pool now being addressed by satellite ocean color instruments). Future research capabilities: A higher resolution double monochrometer spectrometer increased laser power improved CCD detectors are now being investigated to extend the laboratory system sensitivity to allow detection of carbonate ions within natural seawater. The NASA Shipboard Laser Fluorometer Laser detection of sulfate Raman in natural seawater and carbonate Raman in concentrated solution

The high resolution airborne detection of the OH stretch water Raman has been demonstrated (below right) from low altitude airborne LIDAR flights in a Twin Otter (below left) but the weaker bicarbonate ion signals have yet to be detected in the nm spectral region. Why is this important?: It is necessary to acquire all bicarbonate ion signals because the oceans are Earth’s greatest storehouse of carbon primarily in the form these bicarbonate ions. This will eventually lead to a better understanding of the levels that aquatic ecosystems withdraw carbon from the atmosphere and oceans through photosynthesis and replenish it through respiration and decay Twin Otter lidar aircraft at NASA Wallops Flight Facility Water Raman spectrum collected from the Twin Otter aircraft lidar