Synergistic assessment of environmental pollutants and carbon emissions in the Yellow River Basin, China: An integrated study based on scenario simulation and process decomposition

Environmental pollutants (EP) and carbon emissions (CE) generated by fossil fuel combustion have the same root and origin, but the synergistic effect of EP and CE in specific management is not clear. This study develops a systematic method to evaluate the synergistic effect of EP and CE, which combines the EP-CE synergy performance under different scenarios and the process decomposition of "source prevention-process control-terminal output" based on the construction of the EP-CE synergy performance assessment, and forms a complete chain of EP-CE synergy performance assessment under the system view of ecological civilization. Furthermore, the synergy of EP and CE in 79 prefecture-level cities of the Yellow River Basin (YRB) is evaluated as an example. Results show that: (1) The overall EP-CE synergy performance in the YRB is in the transition to high-quality development, and the EP-CE synergy performance of each reaches show the evolution of "the lower the performance, the faster the progress"; (2) The EP-CE synergy performance under the scenario of collaborative pollution control and carbon reduction is significantly higher than those of separate pollution control, separate carbon reduction, or no consideration of environmental constraints, and there are noticeable spatial differences, with the upper reaches having the highest EP-CE synergy performance; (3) The EP-CE synergy performances among the different process decomposition in the YRB needs to be strengthened. The process control had the highest overall performance level, but the inclusion of environmental factors could significantly decrease the performance level, while the opposite is exact for the terminal output. The study provides a multi-scenario and process decomposition approach to assess the synergistic effects of EP and CE, and the scenario simulation assessment, process decomposition analysis, and synergistic control recommendations can be used as references for other regions or countries suffering from both EP and CE to formulate environmentally synergistic management development strategies and improve ecological quality according to local conditions.