Holocene and historic rates of rock coast erosion-A discussion focussed on Southeast England

Cliff erosion is of concern along inhabited coastlines especially under a scenario of increasing sea level rise. Extrapolation of past erosion rates are often used as a first approximation of future rates, which are or form part of the input into numerical models. However, cliff erosion rates in the Holocene are poorly understood. This is due to the generally short record based on historical maps, which can mask or accentuate erosion rates based on different event frequencies, and, for the more recent cosmogenic exposure dating method, it reflects the large number of variables influencing the concentration of cosmogenic nuclides in rocks at the surface of intertidal shore platforms. The study uses historic maps that go back 400 years, updated (to 2020) recent erosion rates, evidence from mid-Holocene terrestrial habitats in front of present-day cliffs, and a geomorphological landscape type interpretation to provide a better understanding of cliff evolution and erosion history for the cliffs in East Sussex (Southeast England). The paper demonstrates that cliff erosion can only have started in the last few centuries with remnants of Eemian cliffs still present in places. This is supported by published 10Be data. The coastline investigated also shows a persistent decrease in erosion rates to less than half the maximum rate observed in the late 19th to early 20th century despite sea level rise. As a consequence, it appears imperative to understand the local drivers of coastal cliff erosion to assess the future consequences of climate change rather than applying general concepts for example in relation to erosion changes with increasing sea level rise.

Automated summary

This study investigates the evolution and erosion history of cliffs in East Sussex, and finds that cliff erosion only started in the past few centuries and is decreasing despite sea level rise. Therefore, understanding the local drivers of coastal cliff erosion is crucial for assessing the future consequences of climate change.