O Green World by Gorillaz is a haunting reflection on the state of the environment and humanity's impact on it. The lyrics express a sense of loss and yearning for a time when the world was not tainted by pollution and degradation. Key themes include environmental destruction, nostalgia for a purer past, and a call for change. Particularly poignant moments include the opening lines that set a desolate tone and the repeated pleas for the 'green world' to protect and heal, underscoring the urgency of the environmental crisis.