The Guardian reported that one of the peaks at risk — Calf Top in the Yorkshire Dales — was only reclassified as a mountain a few weeks ago.
The Ordnance Survey (OS), the UK government body responsible for mapping the country, uses mean sea level as the starting point for measuring mountains, which must be at least 609.6 metres above sea level.
But there are several peaks in England, Scotland and Wales that are only a few centimetres over that threshold.
Mean sea level is calculated as the middle point between high and low tide. According to The Guardian the OS has used the same mean sea level for nearly 100 years but sea level rises due to climate change could them to reassess that marker.
“We have to measure from a fixed point, and there are no immediate proposals for a change, but rising sea levels could obviously be a factor if there is a change in the future,” an OS spokesman told the paper. “Clearly if the fixed point was taken from a higher level, the heights measured would drop by the same amount, and that certainly could affect many hills and mountains.”
Another peak that risks losing its mountain status is Thack Moor in Cumbria, which also only recently became a mountain after its true height was determined to be just 2cm over the 609.6-metre qualifier.
Myrddyn Phillips, an amateur surveyor who helped the OS reclassify Thack Moor, told The Guardian: “It will be incredibly interesting if Ordnance Survey change their datum point as this will affect all known heights throughout Britain, and even if this change equates to only 40-45cm it will affect a multitude of hill and mountain classifications.”