Geodesy is not just for static measurements any more

After three decades and three orders of magnitude of advances, space geodesy is poised for prime time in observing the integrated mass transports that take place in the Earth system, from high atmosphere to the deep interior of the core. As such, space geodesy has become a new remote sensing tool, in monitoring climatic and geophysical changes with ever‐increasing sensitivity and resolution. The transports of mass and energy are key processes that determine the dynamics of our Earth system. The Earth system can be conveniently viewed through its components, so‐called geophysical fluids—the atmosphere, hydrosphere, cryosphere, biosphere, lithosphere, and the deep interior of mantle and cores. All geophysical fluids undergo a host of mass transports for various reasons, external as well as internal. Studying these processes is undoubtedly a most interdisciplinary field in all of Earth sciences. However, mass transport has not received due attentions. For example, all ocean general circulation models (GCMs) working today do not correctly conserve the water mass; instead, they conserve the water volume under the Boussinesq approximation. Neither do the atmospheric GCMs in conserving the dry air mass, including those used daily for weather forecasts. A most critical piece in the global water mass puzzle, the large‐scale land hydrological and cryospheric mass budget remains least known.