This is a Nature Matters Arising submission to the Nienhuis et al., 2020 paper: Nienhuis, J. H., Ashton, A. D., Edmonds, D. A., Hoitink, A. J. F., Kettner, A. J., Rowland, J. C., & Törnqvist, T. E. (2020). Global-scale human impact on delta morphology has led to net land area gain. Nature, 577(7791), 514-518. Abstract: The growing vulnerability of river deltas is the backdrop of a study that identifies 10,848 marine river “deltas” and uses land cover data to claim that global-scale human impact on delta morphology has led to net land area gain (Nienhuis et al., 20201). A scrutiny of the manuscript, workflow and datasets shows that this overarching conclusion is based on an unconventional definition of deltas, fallacious identification of delta area changes, spurious statistics, and data display errors. Together, all of these issues not only do not support the main conclusion of the paper but misinform delta science.

Codes available at: https://github.com/FlorinZai/Global_Delta_Check