Rock coast erosion: An overlooked source of sediments to the ocean. Europe as an example

Abstract

Current assessments of the continent-to-ocean sediment budget assume that river discharge provides 11-21 Gt/a (72-89%) of the global sediment flux to the ocean. The remaining 11-28% supposedly comes mainly from glacially-derived sediments and airborne dust. Until recently, the contribution from rock coasts was estimated to represent 0.4 Gt/a, representing only 2-4% of the total flux. For the first time, and using the most complete global compilation of sea cliff recession rates in Europe, this study evaluates the rock coast contribution to sediment flux. We show that this sediment flux has been largely underestimated, and reveal that cliff derived sediment supply is only three times less than the solid discharge of rivers (111 ± 65 vs. 290 Mt/a) for Europe. This new estimate of the rock coast erosion should be included in future studies on the evolution of the surficial Earth system.