Environmental education (EE) is now clearly specified in educational standards in many parts of the world, and at the same time the view of language learning is moving towards a content and language integrated learning (CLIL) strategy, to make English lessons more relevant and attractive for students (Eurydice, 2006). In this respect, environmental and English instruction can be merged to benefit both purposes and to offer learning experiences that go beyond the school walls. Einztein, the social learning network for the education community, collaborates with the environmental project Inquiry-to-Insight (http://i2i.stanford.edu/) inviting high school students around the world to participate in the International Student Carbon Footprint Challenge (ISCFC), challenging students to learn about the environmental impact of their lifestyle choices on their carbon footprints. In the ISCFC, students use an online carbon footprint calculator to measure the amount of CO2 (carbon dioxide) released by their everyday choices (food, transportation, etc). Teachers then share student data with other classrooms around the globe and use Einztein to engage students in several environmental discussions online using English as the lingua franca. Students use Einztein to reflect upon their own carbon footprint, envision global and local solutions and share knowledge about environmental issues. For this study we focused on a specific discussion and investigated the discourse structure of students from six different countries (USA, Croatia, Switzerland, Iceland, Greece and Bulgaria) reflecting upon their very own CO2 emissions. Preliminary results indicate that the students' presumptions about their own impact are crucial and whether they are English natives or not is not as important when it comes to developing an understanding of their own responsibilities regarding carbon footprint. Thus, in relation to a motivating content, the students' English is productive and sufficient enough for communication and collaboration. [For the complete volume, see ED574893.]