Climate activist Greta Thunberg has warned world leaders the 'eyes of the world will be on them' at a key UN summit next week. 'We are not just some young people skipping school,' she told thousands of school strikers in Manhattan, on a day when millions around the world demonstrated for action. 'We are a wave of change. Together, we are unstoppable.' Subscribe to Guardian News on YouTube ► bit.ly/guardianwiressub Across the globe, millions join biggest climate protest ever ► www.theguardian.com/environment/2019/sep/21/across-the-globe-millions-join-biggest-climate-protest-ever Support the Guardian ► support.theguardian.com/contribute Today in Focus podcast ► www.theguardian.com/news/series/todayinfocus The Guardian YouTube network: The Guardian ► www.youtube.com/theguardian Owen Jones talks ► bit.ly/subsowenjones Guardian Football ► is.gd/guardianfootball Guardian Sport ► bit.ly/GDNsport Guardian Culture ► is.gd/guardianculture