Satellites reveal hot spots of ocean changes in the early 21st century

Ocean change leaves a potentially important imprint on ocean colorimetry. Here, we present an overview and current evaluation of the global ocean color variability from 1998 to 2022, and satellites observe that 36% of oceans (~122 million square kilometers, derived from valid observations) have experienced changes (<i>P</i> < 0.1). In this context, 25% of the area (formerly blue hue) is turning light blue or green, while the remaining 11% becomes bluer, mainly concentrating in the low-latitude oceans. This study further identifies a "direct" notable impact of both sea surface temperature (SST) and climate on ocean colorimetry tendency and anomaly, especially in the low-latitude oceans. Extreme SST events cause "distinct" ocean colorimetry anomalies, although 94% of cases involve relatively small SST fluctuations. Causal analysis reveals important impacts of climate change on equatorial ocean dynamics, particularly ENSO events. Our findings prove the low-latitude oceans as one of the core changing regions that respond to climate change in the early 21st century.