GRACE is unique among remote sensing systems in its ability to " see " below the first few centimeters of the land surface , and it has provided the first global observations of total terrestrial water storage variations . Now that we have more than seven years of GRACE measurements , it is tempting to look for trends in the data . Auxiliary information is almost always required in order to arrive at the correct diagnosis of an apparent trend . Here we will present a map of GRACE derived terrestrial water storage tendencies since 2002 and attempt to explain which are likely to continue due to climatic or human pressures , and which are short - term expressions of natural interannual variability .