Middle school students are learning about climate change in large part through textbooks used in their classes. Therefore, it is crucial to understand how the language employed in these materials frames this topic. To this end, we used systemic functional analysis to study the language of the chapters related to climate change in four sixth grade science textbooks adopted in the state of California. The linguistic variables investigated were: types of nominal groups; processes; circumstances; and the modality system. Our findings showed that these textbooks framed climate change as uncertain in the scientific community--both about whether it is occurring as well as about its human-causation. The implications for science education are discussed in relation to how the current political and public discourses of climate change, rather than the scientific discourse, is influencing how textbooks discuss this topic.