Contribution of climate-driven change in continental water storage to recent sea-level

• Main Authors: P C D Milly, A Cazenave, M C Gennero
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2003
• Subjects: Greenland; Antarc*; Antarctica; Ice; permafrost
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1059.9461

Using a global model of continental water balance, forced by interannual variations in precipitation and near-surface atmospheric temperature for the period 1981-1998, we estimate the sea-level changes associated with climate-driven changes in storage of water as snowpack, soil water, and ground water; storage in ice sheets and large lakes is not considered. The 1981-1998 trend is estimated to be 0.12 mm͞yr, and substantial interannual fluctuations are inferred; for 1993-1998, the trend is 0.25 mm͞yr. At the decadal time scale, the terrestrial contribution to eustatic (i.e., induced by mass exchange) sea-level rise is significantly smaller than the estimated steric (i.e., induced by density changes) trend for the same period, but is not negligibly small. In the model the sea-level rise is driven mainly by a downtrend in continental precipitation during the study period, which we believe was generated by natural variability in the climate system. S ea-level variation is an integrator and indicator of global climate variation. Although the rate of 20th-century sea-level rise is uncertain (1), during the past decades the global mean sea level has been rising at a rate that is still debated, but that might be as large as 1.5-2 mm͞yr (2). Recognized factors that have contributed to the 20th-century (specifically, 1910-1990) sealevel rise (3) include thermal expansion caused by warming of the oceans (0.3-0.7 mm͞yr), melting of glaciers (0.2-0.4 mm͞yr), mass imbalances of Greenland and Antarctica, including a long-term readjustment since the last glacial maximum and a recent climate-related response (Ϫ0.2 to ϩ0.6 mm͞yr), climatedriven loss from closed lakes (0.0-0.1 mm͞yr), and melting of permafrost (0.0-0.005 mm͞yr). In view of the significance of these terrestrial stores, it is important to assess the analogous role of climate-driven changes in ground water, soil water, and snowpack. Such an assessment is also motivated by the realization that these distributed terrestrial stores appear to be the dominant controls of ...