Climate demonstrators on Wednesday triggered a lengthy tailback on Britain’s busiest motorway, warning that a record-breaking heatwave was a dire reminder for urgent action. Members of the group Just Stop Oil climbed gantries over the M25 encircling London, causing police to intervene and vehicles to back up for several miles (kilometres) in one direction. Surrey Police later said a 22-year-old woman who had climbed a gantry was arrested on suspicion of causing a danger to road users, causing a public nuisance and for being a pedestrian on the motorway. Three lanes that were shut as she was brought down were later reopened, the forced added. Temperatures topped 40 degrees Celsius (104 degrees Fahrenheit) in southern England for the first time on Tuesday, with a new record set at 40.3C. The extreme heat caused huge transport disruption and sparked the same kind of wildfires seen in Europe in recent years.