Sea-Level-Rise Trends off the Indian Coasts during the last Two Decades

The present communication discusses sea-level-rise trends in the north Indian Ocean, particularly off the Indian coasts, based on estimates derived from satellite altimeter and tide-gauge data. Altimeter data analysis over the 1993-2012 period reveals that the rate of sea-level rise is rather spatially homogeneous over most of the north Indian Ocean, reaching values close to global mean sea-level-rise trend (3.2 mm yr^-1) estimated over the same period. The only notable exception lies in the northern and eastern coasts of the Bay of Bengal, which experience larger trends (5 mm yr^-1 and more). These recent trends derived from altimeter data are higher than those estimated from tide-gauge records over longer periods during the 20th century. This communication calls for an improved understanding of the mechanisms behind this accelerated sea-level-rise recorded over the past two decades, that could either be a direct response to global warming or a result from an aliasing by the natural variability.