Earth satellite scientists often put up a satellite sensor simply because it can measure some parameter that is known to be fundamental in geophysics, but we don’t know how good it will be or what it will reveal. We can postulate on its accuracy and run models, but until it is up and has a few years of data we don’t know what will be possible. A general rule is: the data is revolutionary, changing old ways of thinking, and can be applied in ways never anticipated.
So it goes for GRACE, which can accurately measure the gravity (actually the mass beneath it). It has been up for over 7-years and a presentation today in Venice shows that it reveals trends, increasing mass in the oceans, decreasing mass in Greenland & Antartica. Draw your own conclusions.
A side note: When new data appear in an old problem, there is a chance to correct bias/errors in some of the existing data. Prior satellites measured sea height, glacier volumes, sea temps and winds, all applied to get sea level height tendencies. (For some reason they’re really interested in this in Venice!).
Science skeptics will nod their heads when I say there were two erroneous trends in the satellite data existing from the two principal satellites. When they disagreed with the new data, all data was carefully checked for errors. Errors were found and corrections to data made. Global Warming deniers will nod their heads when I note that in both cases, the upward warming trend was confirmed. This is probably more an example of the basic conservatism of scientists, usually rejecting the unusual trends, accepting the expected.
We need more than one reinforcement of GW temps to believe it! It was not expected to be as strong as it is appearing to be, as shown here daily in a conference reviewing the satellite data of the past decade.