Coverage of climate change in introductory biology textbooks, 1970–2019

Science textbooks as historical documents Textbooks are important documents to study which information society deems valuable and appropriate [14]. Textbooks represent an authoritative source in education; most teachers identify textbooks as the largest influence on content selection, especially in the sciences [15]. Therefore, analyzing texts for topic coverage and organization, language use, and pedagogical recommendations can inform us of the intentions of curriculum experts, as well as the influ- ences of society or culture. The sequence of chapters can play a critical role in how, or if, content is addressed in the classroom. Controversial topics of reproduction, evolution, and conservation were placed at the rear of biology textbooks in the 1930s, beginning a tradition of book organization still observed today [16]. Instructors usually progress through a textbook from one chapter to the next and, in studies examining teachers’ use of textbooks, chapters at the end of the books are frequently skipped [17, 18]. Visual elements, such as graphs, maps, and photographs, play a positive role in students’ processing, organizing, and recalling textual information [19]. Complex data visuals, incorpo- rated into the text, improve students’ problem-solving and memory of facts [20]. Therefore, the data visuals displayed within the climate change passage should indicate content valued for this reinforcement. Predictions for textbook analysis If curricular decisions are based on progress toward an ideal goal, then we should see move-

ment toward this goal over generations of educational documents. In this case, the goal is a conceptual understanding of the greenhouse effect, the impacts of increasing greenhouse gas- ses, and immediate behavioral, political, and cultural changes to slow or stop global climate change. Our content analysis research focuses on any differences between this ideal goal and the operational curriculum used by teachers and students. While there are multiple other factors influencing the perception of climate change, textbooks are valued for the authoritative roles they play in education systems; this would make the textbook a persuasive instrument in the fight against climate change. We reviewed climate change passages in textbooks published between 1970 and 2019 and predicted that: 1. The amount of climate change coverage will increase. Since textbooks reflect societal values, educational goals, and expert knowledge, we predict that the length of the climate change passage in introductory biology textbooks will increase substantially over time. Scientists since the 1970s have gained more understanding of the topic of climate change, and the public’s awareness of the issue has grown as environmental conditions have worsened and the urgency of prevention or restoration increased. 2. The passage addressing climate change will move forward in the textbook. We expect that the sequence of chapters will transition from the traditional end-of-book placement of conservation issues to shift earlier in the book, indicating increased impor-

tance, decreased perception of controversy, and a reduction in the likelihood that instruc- tors will omit the content. 3. The climate change passage will shift from a description of the greenhouse effect to incor- porate coverage of effects and solutions over time. The solutions will also shift from a national or international focus to include productive individual or local actions. PLOS ONE Climate change in biology textbooks, 1970–2019 PLOS ONE | https://doi.org/10.1371/journal.pone.0278532 December 21, 2022 3 / 16