Extinction Rebellion's Chichester branch protested in the city centre on Saturday (August 10).
Members of the climate activism group met by the cross and held a die-in to raise awareness about the climate emergency and potential rising sea levels.
A die-in was also held with members representing different various local towns and would be lost to the with rising sea levels..
A spokesman for the group said: “If the government allows the nation to continue on its current course, with a 'business as usual' approach, then much of the world's flora and fauna is doomed, and humanity, too, could be facing extinction.
"The government recognises this fact and Parliament has declared a Climate Emergency – but very little is being done. The Environment Agency has said that the nation must prepare for a 2° to 4°C temperature increase and for a sea-level rise which will eventually put many of our local villages under water.
"Felpham, for instance, will become a harbour with just ONE METRE of sea level rise and Selsey will become an island! So we would like the government to do something more than simply acknowledge the state of affairs. In fact, we insist on it. And that is what this XR protest is all about.”
"We're hoping it won't come to this,” said Nick Schinas, a participant from Bognor. He said: “All we need to do, in order to stop the temperature from rising, is to stop emitting carbon gases. Obviously, that won't be easy - but at the moment, we're not even really trying.
"The government has declared a climate emergency, but that's all they've done. They've said that Britain's net emissions will be reduced to zero by 2050, but they haven't actually introduced any policies which will help to get us towards that target.”