Drone footage filmed at Beachy Head in Sussex shows a huge crack forming in the side of the cliffs with people being told to avoid the area.
It comes as a study revealed Eastbourne, Swale and Dover are some of the areas most at risk of being lost due to rising sea levels by the 2050s.
The study, from the peer-reviewed journal Oceans and Coastal Management, says sea levels will be around 35cm higher by 2050 in England than their historical level.
Foreshores, the part of a shore between high and low water marks, are also at risk of being eroded.
Professor Jim Hall, Professor of Climate and Environmental Risks and former Director of the Environmental Change Institute at the University of Oxford said: "We need to have honest conversations with coastal communities that it will simply not be possible to protect every house and business from sea level rise.
"These changes are coming sooner than we might think and we need to plan now for how we can adjust, including a nationwide strategic approach to deciding how to manage the coast sustainably in the future."