Up to 100 miles of Wales' coastline is at risk of erosion over the coming century, the National Trust is warning.
More storms are predicted to batter the coastline
The organisation, which owns 10% of the Welsh shore, said rising sea levels and an increase in storms were to blame.
The tip of the Llyn peninsula and parts of Gower are most at risk if the sea were to rise a predicted 86cm (33in).
At present, there is no way for the public to find out if their homes are threatened. The trust said people had to work with the forces of nature.
After the south-west of England, Wales has the longest area of coastline likely to be affected by erosion, according to the trust.
It said 169km (105 miles) of shore and up to 788 hectares (1,947 acres) of surrounding land would be hit within the next 100 years.
The trust wants greater public awareness of the looming problem.
It believes improving sea defences is unaffordable and, in many cases, counter-productive, as it can create greater problems for communities and the environment elsewhere.
It said people had to accept the forces of nature and devise new ways of compensating those affected.
The trust also wants decision making to be simplified. At present, over 30 local agencies and authorities are currently involved in coastal management, which the trust said made finding accountable solutions difficult.
Last December, a report presented to Carmarthenshire council estimated up to £20m may be needed to build sea defences to protect Llanelli's Millennium Coastal Path from the sea.
Over a stretch of just 10 miles, a sea wall at Llanelli was in danger of collapsing, there was erosion at Burry Port and sand dunes at Pembrey were reported to be disappearing.
A recent report headed by the government's chief scientific adviser estimated the costs from flooding and coastal erosion could rise from about £1bn at present to £20bn by 2080.