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

Sentence topic analysis Each sentence in the passage about climate change was coded as: 1) a description of the green- house effect, 2) effects of climate change, or 3) actionable solutions for the problem. In the 1970s textbooks, the content was almost exclusively a description of the greenhouse effect (Fig 4). The description sentences decreased to approximately 50% of the content in the 1990s, remained stable through 2009, and then decreased to less than 40% in the last decade. The average number of description sentences was the same in 2000–2009 and 2010–2019 (23.6 and 23.7, respectively), yet the passage grew overall due to the number of sentences addressing effects of climate change (an average of 22.4 in the 2000s and 41.4 in the 2010s). Coverage of the consequences of climate change in the most recent books is almost double the description of the greenhouse effect. Sentences offering actionable solutions peaked in the 1990s, at 15.5% of the passage, and declined in the most recent books, to 3.1% of the passage. We further categorized the effects of climate change addressed in textbooks published from 1990 to 2019 (earlier decades had few sentences addressing the consequences of climate change). Impacts on extinction rates made up the largest number of sentences in all three decades, and the topic increased over time. The coverage of climate’s impact on sea level rise, agriculture, rainfall, and temperature all decreased over time, while coverage of human health

Fig 1. Amount of coverage addressing climate change in college introductory biology textbooks. The average amount of coverage increased over time, though the largest increase occurred in the 1990s. Due to the large range in passage length, the median number of sentences for each decade was calculated. The 1990s still showed the largest increase in passage size, though textbooks published in the 2010s decreased in median length. https://doi.org/10.1371/journal.pone.0278532.g001 PLOS ONE Climate change in biology textbooks, 1970–2019 PLOS ONE | https://doi.org/10.1371/journal.pone.0278532 December 21, 2022 7 / 16