Argo AT A CROSSROADS ACHIEVEMENTS, IMPACTS, AND THE IMPERATIVE FOR SUSTAINED GLOBAL OCEAN OBSERVATIONS

Over the past 25 years, the international Argo program has become the backbone of subsurface ocean observation and a prime example of a highly successful, sustained global scientific collaboration. Through evolving technology, the program has become more efficient while also expanding its suite of observations, with a subset of floats equipped with biogeochemical sensors or the ability to sample below 2,000 m water depth. By delivering continuous, global measurements essential for climate science and national security operations, Argo observations underpin advances in understanding ocean heat uptake, circulation, carbon cycling, deoxygenation, and marine ecosystem variability, while also supporting operational forecasting, ocean reanalysis, and coupled Earth system prediction. Here, we synthesize Argo’s scientific, operational, and societal contributions while emphasizing the importance of sustained continuity and expansion of the observing system. We, members of the US CLIVAR Phenomena, Observations, and Synthesis Panel, argue that Argo has become an indispensable global infrastructure whose long-term value depends on maintaining consistent global coverage and data quality. Emerging advances in biogeochemical sensing, deep-ocean observations, artificial intelligence, and data systems provide opportunities to further strengthen the network, but continued investment and international coordination are essential to preserve and expand humanity’s capacity to monitor and predict a changing ocean and climate system.