Assisted by fellow islanders and visitors, Roc Sandford blocked the route with a boat.
He said: “The boat symbolises sea level rise. Gometra is already sinking, and blocking the bridge is intended to raise consciousness of the unfolding emergency by means of disruptive non-violent direct action.”
With only eight residents, Gometra, which is connected at low tide by a causeway and bridge to Ulva, does not attract much traffic.
Land Rovers and quad bikes are the only vehicles which normally attempt the eight-mile route across the rough track from Ulva.
But Mr Sandford, 61, who ditched his own quad bike two years ago and swapped his car for a bicycle, says Gometra’s action aims to highlight its solidarity with other islands, such as Fiji, which are sinking because of climate change. For more than 25 years, Mr Sandford, who farms a flock of 350 sheep on Gometra with help from a neighbouring family, has watched as the changing weather patterns have taken their toll on the island he loves.
The father-of-four said: “Islands are especially vulnerable. Gometra is already experiencing unseasonal weather extremes and sharp declines in our biodiversity.
“Sea level rise will flood our fertile machair and our causeway to the neighbouring island of Ulva. The incipient failure of the Gulf Stream will cause unexampled extremes of cold weather.
“Elsewhere on the world’s islands, people are dying because of climate and ecological collapse, and we affirm our solidarity with them.”
He added: “Gometra is off-grid and attempting to embody low-impact lifestyles, but we have much further to go and our ambition and hope is to be carbon-neutral before 2025.”
A number of South Pacific nations have already declared a climate emergency, claiming that developed countries have failed to act to halt the consequences their islands face, including the prospect of some areas becoming uninhabitable as early as 2030.