On the 15th of March 2019, more than 1.6 million students have protested in 125 countries against the climate change effects, as part of the Fridays for Future movement. The manifestations represented the biggest day of global climate action ever taken, according to media outlets. At the core of this movement stands Greta Thunberg, a Swedish 16-year old climate activist and a Nobel Prize nominee, whose actions and speeches serve as inspiration for both students and adults. 

With a focus on environmental communication and climate activism, this research aims to find how the teenager addressed climate change topics and how she succeeded in conveying her ideas to audiences. It discusses how the rhetoric was constructed within her speeches, and which of the argumentative elements gave Greta Thunberg the ability to convince the public. The study combines frame and rhetoric analysis with a focus on the text of the speeches that Greta Thunberg delivered in three major international events. The purpose is to observe and understand the nature of Greta Thunberg’s activism by analyzing how the high school student used the linguistic tools and tactics in her public speeches, and to explore a few theories within the text: the issue framing of the climate crisis; the argumentative and discursive techniques that helped her to gain media and public attention. 

The thesis concludes that the evolution of Greta Thunberg’s climate activism, from ‘no attention’ to global reputation, is based on grassroots activism, particular personality features, and efficient use of rhetoric devices combined with moral purpose argumentation.