Climate activists from Just Stop Oil painted over the grave of British naturalist Charles Darwin at London's Westminster Abbey on Monday.

Two activists entered Westminster Abbey - Britain's site for royal weddings, coronations, burials and a major tourist attraction - on Monday morning and used spray chalk on Darwin's grave, the campaign group said in a statement.

The activists wrote "1.5 is dead" in orange over the surface of the white marble gravestone - a reference to recent news that global temperatures in 2024 had exceeded 1.5 Celsius above the pre-industrial era for the first time.

"We have passed the 1.5 degree threshold that was supposed to keep us safe," one of the activists said. "Darwin would be turning in his grave to know we are in the midst of the sixth mass extinction."

Darwin, best known for his theory of evolution by natural selection, died in 1882. He is buried in Westminster Abbey's Scientists' Corner, where Isaac Newton and Stephen Hawking are also buried.

The church confirmed the incident in a statement.

"The Abbey’s conservators are taking immediate action to clean the memorial and do not anticipate that there will be any permanent damage," a spokeswoman said.

"The police were called to the scene and dealt with the incident. The Abbey remains open for visiting and worshipping."

London's Metropolitan Police said two women had been arrested on suspicion of causing criminal damage at Westminster Abbey and taken to a central London police station.

Just Stop Oil activists have staged a number of high-profile protests in Britain including by disrupting sports and theatre events, painting over the U.S. embassy building in London and throwing soup at Van Gogh paintings.