Overview
- A deep-learning analysis of daily chlorophyll data from satellites and monitoring ships shows a significant decline in ocean greenness between 2001 and 2023 of about 0.35 micrograms per cubic metre per year.
- The study estimates an annual 0.088% drop in the oceans’ carbon sequestration capacity, equal to roughly 32 million tons.
- Declines are markedly stronger in coastal waters, about twice the basin-average rate, and more than four times greater near river estuaries.
- Authors attribute the trend to hotter surface layers intensifying stratification that suppresses nutrient transport to phytoplankton in low- and mid-latitude oceans.
- The findings challenge earlier reports of increasing algal blooms, acknowledge regional variability and runoff effects, and call for stricter coastal pollution controls alongside accelerated emissions cuts.