According to the IPCC Fourth Assessment Report (FAR) (IPCC, 2007), global mean sea level may increase by 0.5 m over the next 50 to 100 years, and more if significant accelerations occur in the next couple of decades. There is already evidence of a recent acceleration. Current satellite altimeter observations show sea level rising at ~3 mm/yr, nearly twice as fast as the tide gauge measured rate over the past 100 years. Does the altimeter record reflect a long-term change or just natural decadal variability? What processes are responsible for this apparent increase and how reliable are the IPCC/ FAR model projections? The answers to these questions are critically important to understanding the causes of sea level rise and it's impact on society. We use a combination of TOPEX/Jason/Jason-OSTM altimeter observations of total sea level change, GRACE gravity observations of ocean mass change, and Argo profile observations of ocean density change to determine the current sea level budget as accurately as possible. We use this information to evaluate the performance of the FAR model simulations and a model reanalysis with the goal of trying to improve the reliability of long-term projections of sea level rise. At the core of this work will be an intensive effort to verify, calibrate, and improve the accuracy of observations from multiple altimeter missions. This work encompasses the study of heat and mass change in the ocean by different types of satellite and in-situ observations, consistent with NASA research goals in the areas of climate and climate variability.
Sea Level Rise from Satellite Altimetry