Sian joined Extinction Rebellion (XR) in November 2018. She has participated in all of its major London-based actions. She is a founding member of two local XR groups in Wales. She coordinated the training of XR activists across Wales until October this year. 

She delivers two public talks - 'Heading for Extinction (And What To Do About It)' and 'What is a Citizens' Assembly and Why is it XR's Third Demand?' - and trains other activists to deliver them. She also trains activists in non-violent communication: to listen to the anger of ordinary people disrupted by XR actions with empathy and respect; and to tell the truth about the gravity of the climate and ecological emergency with compassion. 

She is currently a coordinator of XR Cymru's work to raise awareness about Citizens' Assemblies. Her paid work is as a therapeutic caseworker with young people who have issues with substance misuse.