Remote Sensing‐Based Assessment of Carbon and Water Ecosystem Services in Response to Climate and Vegetation Cover Changes Across Global Major River Basins

ABSTRACT Improving our understanding of terrestrial carbon‐water coupling processes at the basin scale is crucial for assessing the impacts of global change on river basin's ecosystem services. Supported by remote sensing technology, previous studies have investigated the variability of carbon sequestration or water yield of a basin separately. However, the integration of these two components in an assessment system has rarely been considered, which may lead to partial appraisals of eco‐hydrological services. To address this knowledge gap, we have developed a new remotely sensed index, the Carbon‐Water Efficiency Index (CWEI), which is derived as the product of the normalized precipitation use efficiency (PUE) and water yield efficiency (WYE) during a specified period for a given basin, to quantify the coupling carbon‐water ecosystem service. In this study, the spatial and temporal variabilities of CWEI were investigated using satellite‐based products across the 38 major river basins from 1982 to 2016. Furthermore, the response patterns of CWEI to its components were explored, and the contributions of the three variables (i.e., temperature, precipitation, vegetation coverage) on changes in CWEI were quantified for each of the basins. The results demonstrated that the CWEI exhibited an increase in 31.6% of the world's major river basins, of which 83.3% with an increasing CWEI demonstrated a response pattern of increasing PUE and decreasing WYE. Furthermore, temperature was identified as the primary contributor to CWEI in 50% of the basins. It is noteworthy that green hotspot basins, where afforestation projects were underway, exhibited enhancements in reduced water yield pressure and demonstrable benefits to local ecohydrology. The proposed CWEI provides a new framework for comprehending the sustainable development of river basins worldwide.