According to Wikipedia, Climate Justice Now! (CJN!) is a global coalition of networks and organizations campaigning for climate justice. The coalition was founded at the 2007 United Nations Framework Convention on Climate Change (UNFCCC) meeting in Bali, and has since mobilised for UNFCCC meetings in Bangkok, Copenhagen and Cancun.
In a statement in 2008, CJN said that “Climate Justice Now! is a network of organisations and movements from across the globe committed to the fight for genuine solutions to the climate crisis. We are committed to building a diverse movement – locally and globally – for social, ecological and gender justice.”
Their website (https://climatejusticenow.org/) seems to have been inactive since 2012.
See here for an introduction to the concept of Climate Justice.