Stonehenge spray-painted orange by Just Stop Oil protesters

The group said in a statement that it is “demanding that our next government sign up to a legally binding treaty to phase out fossil fuels by 2030.” It added that the paint was made of corn flour that will wash off with the rain. It identified the protesters involved as Niamh Lynch, 21, and Rajan Naidu, 73.

Local police said they had arrested two people following the incident.

English Heritage, the charity that manages Stonehenge, said the site remains open. “Obviously, this is extremely upsetting and our curators are investigating the extent of the damage,” it said on social media.

British Prime Minister Rishi Sunak tweeted after the incident that Just Stop Oil was “a disgrace.” Opposition leader Keir Starmer was also critical, saying in a post that the “damage done to Stonehenge is outrageous” and that those “responsible must face the full force of the law.”

There have been a spate of protests involving historic objects and art in recent years, with activists splattering paint, soup and other substances on artworks such as the Mona Lisa and Van Gogh’s “Sunflowers” to call attention to issues including the climate crisis — and prompting an international plea from museums for them to stop.

This week’s incident, however, seems like “a bit of an escalation,” said Shannon Gibson, a professor at the University of Southern California who researches global environmental politics and social movements. While previous incidents in museums typically left only surface-level damage to the protective cover of an artwork or historic object, the protesters at Stonehenge placed paint directly on a renowned UNESCO World Heritage site.

Critics say such protests can alienate potential supporters of climate justice movements and create spectacle rather than effect change.

But Gibson said protest is meant to be a spectacle — and that protests at sites like museums and historic monuments reach individuals who may be sheltered from the impacts of climate change.

“We don’t need to protest on the islands, on the coasts or in the Arctic — they get it, they know it, they live it,” she said. “This is saying to the people that hold the money, make the decisions and control the fossil fuels: ‘This is affecting you, too.’”

In targeting an ancient structure, something people “think could never change,” Gibson said, such protests provide “a juxtaposition between what has withstood the test of time and what will not if we don’t solve the climate crisis.”

Stonehenge’s unique stone circle was constructed about 2500 B.C. to align with the movements of the sun. On the summer solstice — the longest day of the year — thousands gather to watch the sun rise through a gap in the outer circle of stones.

UNESCO describes the site as the “most architecturally sophisticated prehistoric stone circle in the world.”