Protected marine areas are at risk too

24% of Earth’s sandy beaches, a coastline distance of almost 50,000 miles, is eroding

The world’s sandy shorelines are declining in protected marine areas which could threaten plant and animal species and cultural heritage sites, a global survey of beaches with satellite data from NASA and the US Geological Survey shows.

Worldwide, the study found that 24 per cent of Earth’s sandy beaches are eroding, a coastline distance of almost 50,000 miles, NASA said in a statement.

The view from space provided a team of scientists and engineers from the Netherlands with a more accurate picture of just how much of Earth’s shorelines are beaches.

They found that about a third (31 per cent) of all icefree shorelines are sandy or gravelly. Africa has the highest proportion of sandy beaches (66 per cent) and Europe has the lowest (22 per cent).

The team used machine learning to “teach” its classification software to accurately identify sandy beaches from images taken by Landsat satellites from NASA and the US Geological Survey.

This allowed them to quickly and automatically examine 30 years of data and determine how many of Earth’s beaches are sandy instead of rocky or icy, and how those sandy beaches are changing with time. “It only took about two months’ calculation time to generate this data set of annual shorelines between 1984 and 2016 for the entire world,” said Arjen Luijendijk, a coastal development expert at Deltares, an independent research institute in the Netherlands.

“The alternative of taking aerial images, placing the images in world coordinates, and sometimes manually detecting shorelines, takes weeks or months to capture a coast longer than 50 miles,” Luijendijk said.Taking this kind of global snapshot gives scientists a clearer idea of what large scale processes govern the growth and retreat of beaches around the world, Luijendijk said.