Half the world’s beaches to disappear by 2100
Published: 2 March 2020
A group of scientists from IHE Delft and Deltares, and led by the European Commission’s Joint Research Centre, have today published the first global projections of how sandy beaches around the world are expected to change over the course of the next century. Their findings emerge from combining 35 years of satellite observations with 80 years of climate and sea level changes as predicted by a range of climate models.
Climate mitigation and adaptation challenges ahead
The study shows that without climate mitigation and adaptation almost half of the world’s sandy beaches are under threat of near extinction by the end of the century. In addition to the loss of valuable ecosystems, the associated socioeconomic implications would be severe, especially in tourism-dependent communities where sandy beaches are the main tourist attraction. Small Island nations are among these more vulnerable regions.
In most parts of the world, the projected shoreline dynamics are dominated by sea level rise (RCP4.5 and 8.5), meaning that moderate greenhouse gas emission mitigation could prevent up to 40% of the projected shoreline retreat globally.
Sandy beaches currently account for more than 30% of the world’s coastlines. They are important natural habitats and serve as natural buffer zones that protect the coastline and coastal ecosystems from waves, surges and marine flooding. Their function as shock absorbers will become increasingly important with the rising sea levels and more intense storms that are expected from climate change. In many cases these same beaches also provide important coastal recreational areas and are fundamental to the livelihoods of millions. Today around 10% of the global population currently lives in low-lying coastal zones that are less than 10 m above sea level; a number which is expected to rise.
Different challenges for different countries
Discussing the significance of the findings, Rosh Ranasinghe, Professor of Water Science and Engineering at IHE Delft, highlights their importance at both global and national levels.
“This is the first time fully probabilistic (as opposed to deterministic) projections of future coastline change have been provided at global scale, and as such the utility of the projections are high for emerging risk-informed coastal management/planning frameworks.” He added that in addition to the global outlook, the group’s findings also provide country-by-country analyses that indicate major coastal adaptation needs for different countries.
“By the end of this century several countries, including Congo, Suriname, Comoros, Benin, Pakistan, Guinea and El Salvador could face losing more than 80% of their sandy coastlines. In terms of total length of coastline, Australia emerges as the potentially most affected country with 12,324 km – 15,439 km of sandy coastline threatened by erosion.”
Arjen Luijendijk, researcher at Deltares and TU Delft, sees a positive message from the present analysis as well: “While SLR will drive shoreline retreat almost everywhere, many locations show ambient erosive trends related to human interventions. The erosion could be avoided by more sustainable coastal zone management practices. Site-specific coastal planning can mitigate beach erosion, like we do in The Netherlands. Assuming a continuation of the present Dutch nourishment policy and its effectiveness until 2100 will result in sufficiently wide beaches at the Holland coast, that can cope with the projected shoreline retreat due to future sea level rise of up to 1 m and extreme storms”.
Deltares contributed to the study by providing global data on the ambient historical shoreline change rates, sandy beach occurrence maps and coastal slopes. The global future shoreline data for RCP4.5 and RCP8.5 will be added to the ShorelineMonitor per sandy transect in the next days.
You can read the full Nature Climate Change article, titled ‘Sandy coastlines under threat of erosion,’ here.
The projections detailed in the Nature article is intended to contribute to Chapter 12 of the Working Group I contribution to the sixth assessment of the Intergovernmental Panel on Climate Change (IPCC AR6), which will be finalized next year.
- Dr Michail Vousdoukas is a Scientific Officer in the Disaster Risk Management Unit of the European Commission’s Joint Research Centre.
- Professor Rosh Ranasinghe is the Head of IHE Delft’s Department of Coastal & Urban Resilience & Risk and holder of the prestigious AXA Chair in Climate change impacts and coastal risk. He is also coordinating lead author of IPCC AR6.
- Dr Arjen Luijendijk is an expert in the field of global shoreline dynamics and morphological modelling of nature-based solutions at Deltares.
- Luc Feyen is a researcher at the European Commission’s Joint Research Centre.
- Lorenzo Mentaschi is an oceanographer at the European Commission’s Joint Research Centre.
- Theocharis Plomaritis is a coastal oceanographer specialized in sediment transport, coastal morphodynamics and associated hazards during high energy low frequency from events at the University of Cadiz.
- Panos Athanasiou is a PhD candidate working on coastal hazards and coastal risk assessment at Deltares and the University of Twente.