Beaches can survive rising sea levels if they have room to move

An international team of coastal scientists has rejected suggestions that half the world’s beaches could go extinct over the course of the 21st century.

The claim was made by European researchers in a paper published in Nature Climate Change in March 2020 (Sandy coastlines under threat of erosion by Vousdoukas et al).

However, academics from the UK, France, South Africa, Australia, New Zealand, and the US have reviewed the data and methodology that underpinned the original study and say they strongly disagree with its conclusion.

They have now published a rebuttal to the article in the same journal and concluded that with the global data and numerical methods available today it is impossible to make such comprehensive and far-reaching predictions.

Crucial to their disagreement with the original document’s conclusions is the fact that they claim that there is the potential for beaches to migrate to land as sea levels rise and coasts recede.

The key notion behind this is that if beaches have room to move to under the influence of sea level rise – referred to as accommodation space – they will retain their overall shape and form but in a more landward position.

The new research says beaches backed by hard coastal cliffs and engineering structures, such as dikes, are likely to disappear in the future due to sea level rise as these beaches are unable to migrate to land. They will first experience “coastal compression” resulting in a decrease in width and eventually drown.

However, beaches backed by low coastal plains, shallow lagoons, salt flats and dunes will migrate to land due to rising sea levels. In these cases, the shoreline will recede, but the beaches are likely to remain, albeit a little raised in elevation and located towards the land, and certainly will not “die out”.

The new document states that there is currently no information available globally on the number of beaches that fall into either category, and as such, it is impossible to quantify what percentage of the world’s beaches will disappear between now and 2100.