Dressed all in black, members of Extinction Rebellion Brighton lay down on the floor of the Churchill Square Shopping centre in Brighton, East Sussex, for 11 minutes at 3pm.
The group said this was to symbolise the 11 years we have left to act to avoid climate catastrophe, according to the Intergovernmental Panel on Climate Change’s recent report.
They were joined by Brighton Extinction Rebellion’s choir, who sang This is an Emergency – the group’s anthem.
A spokesman from Extinction Rebellion Brighton said: “Humans are facing an unprecedented global emergency.
“Scientists believe out planet has entered a period of abrupt climate breakdown.
“We are witnessing a mass extinction bigger and faster than the one that killed the dinosaurs.
“The earth’s atmosphere is already 1°C warmer than pre-industrial levels.
“The chances of staying below the 2° C limit set by the Paris Agreement is tiny. Projections show at least 3° C of warming is likely.
“People in Brighton tend to be more conscious than most of the reality of the situation.
“The city has a Green Party MP and has long been known for its progressive and eco-friendly ethos.
“However, the truth is that most are still not fully aware of the unimaginable horrors we and our children will face – as a result of floods, wildfires, extreme weather, crop failures and inevitable societal breakdown – if governments around the world keep failing to act.
“We hope our fellow citizens understand that this is why we interrupted their Saturday afternoon shopping trip. We urge them to join us.”