How Salty Is the Global Ocean: Weighing It All or Tasting It a Sip at a Time?

Global ocean mean salinityS ¯is a key indicator of the Earth's hydrological cycle and the exchanges of freshwater between land and ocean, but its determination remains a challenge. Aside from traditional methods based on gridded salinity fields derived from in situ measurements, we explore estimates ofS ¯based on liquid freshwater changes derived from space gravimetry data corrected for sea ice effects. For the 2005–2019 period analyzed, the differentS ¯series show little consistency in seasonal, interannual, and long‐term variability. In situ estimates show sensitivity to choice of product and unrealistic variations. A suspiciously large rise inS ¯since ∼2015 is enough to measurably affect halosteric sea level estimates and can explain recent discrepancies in the global mean sea level budget. Gravimetry‐basedS ¯estimates are more realistic, inherently consistent with estimated freshwater contributions to global mean sea level, and provide a way to calibrate the in situ estimates.