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

Figure analysis While textbook passages about climate change appeared in the 1970s, few data visuals were pre- sented until the 1990s. The number of data figures increased over time but have remained small (from an average of 1.2 data figures in the 1990s to an average of 2.6 data figures in the 2010s). The most common data figures are those that display CO2 levels and global temperatures. Almost every textbook published after 1988 showed a combined figure of these data series. These figures peaked in the 1990s and 2000s. In the 2010s, qualitative photographic evidence (e.g., glacial melt) sharply increased. Maps showing the impact of climate change on species movement also appeared in the 2000s and increased through the 2010s (Fig 7). Discussion and conclusion After analyzing the climate change content from five decades of introductory college biology textbooks, our findings indicate that the amount of content, placement within the book, and communication of solutions have not kept pace with the severity or scope of the problem. However, coverage of the effects of climate change, in text passages and figures, has increased and diversified over time. Amount of content We expected the amount of content to increase in proportion with publications on climate change and the severity of societal and environmental consequences. Despite the large growth in climate change research, funding, and journalism since the early to mid-2000s, textbooks have not reflected the same increased emphasis. The average size of the passage on climate

change grew more slowly in the 2000s; the median length of the passage surprisingly decreased in the 2010s. The stagnancy in climate change coverage may have multiple influences, includ- ing societal concerns, student mental wellness, and author interest. First, societal influence could have played a role in the decrease of content. The Kyoto Pro- tocol, Earth Day 2000, the film An Inconvenient Truth, multiple UN climate change confer- ences, and IPCC publications increased total media coverage of climate change from 1998 through 2010. This attention, however, was often met with backlash or controversy (e.g., 2010 IPCC email scandal, NSTA decline of 50,000 free copies of An Inconvenient Truth, or the polit- ical conservative alignment with the fossil fuel industry) [25]. Given the role of Texas in fossil Fig 6. Specific solutions for climate change addressed within the climate change passage of college introductory biology textbooks. Textbooks have focused on national and international actions, averaging over 80% of the solution-focused sentences. Sentences addressing individual or local actions were few. Of those, most suggestions described behaviors with a low impact on carbon emissions. https://doi.org/10.1371/journal.pone.0278532.g006 PLOS ONE Climate change in biology textbooks, 1970–2019 PLOS ONE | https://doi.org/10.1371/journal.pone.0278532 December 21, 2022 10 / 16