Fig. 2: Trends and patterns of global continental coastal waters from 2000 to 2023.
From: Global coastal water clarity has increased due to human intervention
a Spatial classification of SPM trends in global continental coastal waters based on model-derived annual mean concentrations from 2000 to 2023. Trends are categorized into five classes: Further Clearing (dark blue), Gradually Clearing (light blue), Steady (white), Gradually Turbidifying (light orange), and Further Turbidifying (dark red). Pie charts indicate the proportional distribution of each trend class by continent: NA (North America), SA (South America), EU (Europe), AF (Africa), AS (Asia), and OC (Oceania). Insets (outlined in dark purple) highlight four representative river mouths and delta systems in Asia: (1) the Yellow River Estuary in China, (2) the Yangtze Estuary in China, (3) the Mekong Delta in Vietnam, and (4) the Ganges-Brahmaputra Delta in Bangladesh. b Temporal change in the average distance between the coastline and the spatial boundary where SPM concentrations match the 2000 global mean. Blue line shows the inland retreat of turbid waters; the orange line shows the declining trend in global annual mean SPM concentrations. Shaded bands represent 95% confidence intervals. Both trends are statistically significant (P < 0.01). c Contribution of each trend class to the global change in coastal SPM concentrations. Negative values indicate decreasing SPM (clearing), while positive values indicate increasing SPM (turbidifying). Contributions are calculated as the product of slope magnitude, pixel count, and mean concentration.
