If you were an American college student studying biology in the 1970s, your course textbook probably contained information about standard topics like photosynthesis, cellular division, genetics and food chains. But you might also have come across something less expected, tucked in the last few pages of your book: an explanation of the greenhouse effect and what it could mean for global temperatures in the future. 

“​​I was really, really surprised that it had been in our textbooks for that long,” said Jennifer Landin, an associate professor of biological sciences at North Carolina State University whose accidental discovery of a passage about global warming in a 1978 textbook sparked the idea to conduct a study of climate change coverage in undergraduate course materials. In the study, published in December, Landin and her co-author, Rabiya Arif Ansari, sought to understand how climate change was taught in college classrooms by analyzing 57 textbooks from the past 50 years. 

They found that textbooks’ coverage of climate change expanded from 1970 to 2019, but that the increase was inconsistent and that the books had failed to keep pace with the volume of new scientific research on the topic, especially in the last 20 years. More surprisingly, in the 2010s, textbooks contained fewer sentences about climate change than they had in the 2000s. Landin and Ansari also found a decrease in content addressing solutions to climate change, after a peak in the 1990s, and a trend of moving climate information further and further back in the book. 

One reason it matters what kind of climate information can be found in our textbooks, Landin said, is their audience, which includes the next generation of scientists, health-care workers, science teachers and researchers. “It’s important to consider that the behaviors that they form or reinforce at this stage in their lives will be hugely impactful,” she said. What young adults learn in school affects how they will view their roles in climate mitigation and adaptation, not just as students but for the rest of their professional and personal lives. 

For educators, textbooks sometimes serve as a “guide to what is expected to be taught,” and they can act as a counterbalance to the varying beliefs of individual teachers. The study notes that significant numbers of teachers approach climate change as a controversial issue that needs to be presented from “both sides,” and that some of them are still teaching students that global warming has natural causes, not human ones. My own education reflected this disparity. I had an exceptional middle school science teacher who taught us about the greenhouse effect in an engaging and thoughtful way, but in high school, one of my science teachers insinuated in class that global warming was caused by natural processes and not by burning fossil fuels, which sowed confusion among his students. In my biology course, the topic was not covered at all.

If textbooks contain little information about climate change and the teacher doesn’t supplement that content with other lessons, it sends a signal to students that it’s not an urgent issue. “If there’s minimal content, we’re implicitly telling people that this topic is worth a few pages way at the end of the book,” Landin said. “And that implies that it’s not important.” Textbooks offer a window into the priorities of the time and place in which they were published. To continue to produce textbooks that treat climate change as a tangential topic telegraphs a failure to grasp how much climate change will alter our future–and has already gravely altered our present. 

In the 1970s and ‘80s, the space that biology textbooks devoted to climate change–and the authors’ certainty about how greenhouse gases would ultimately affect global temperatures–varied, but the topic wasn’t uncommon. (The greenhouse effect has been known since the 19th century, an understanding that was solidified with further research in the 1950s and ‘60s.) Just like the textbooks of the 21st century, the books in use a generation ago give us a glimpse into the thinking of a particular time, one that turns out to be not so different from our own. 

One example appears in a 1982 textbook, “Elements of Biology,” which suggests that increasing levels of carbon dioxide in the atmosphere “could dramatically cause the world’s temperature to rise.” 

“It has been estimated that a rise of 2°C in the annual mean temperature would not only produce significant climatologic changes but would cause the glacial ice caps to melt,” the book explains, which would lead to catastrophic sea level rise and threaten to “submerge many of the world’s major cities.” 

Even textbooks from this era that don’t explicitly address global warming still warn of a looming “ecological crisis” triggered by pollution, deforestation, dwindling resources and an exploding human population. “Life on Earth,” from 1978, concludes with a bleak prediction: 

“We believe that mankind is about to enter one of the Dark Ages of human history. Most of the ecological problems that threaten us will be resolved by the end of the 21st century, either by human intelligence or by nature’s ruthless indifference.” 

“Biology: The World of Life,” also from 1978, strikes a similar tone in a section that feels both prescient and eerily familiar. “Will it be said by the survivors of our era that we stupidly and insensitively foreclosed their future and demeaned their existence? Will our children curse us?” the book asks. Unlike “Life on Earth,” “The World of Life” leaves the door of possibility open, if only a sliver: “Or will they gratefully stand in admiration of our strength, dignity and wisdom at a time when decisions are hard?” The book is frank with its readers, telling them that the answers to these questions “depends on what you do, what you will allow and what you simply will not allow.”

What will the science textbooks of tomorrow have to say about today, about what we allowed and what we did not? “The World of Life” was published 44 years ago, a message in an academic bottle from the past. But its questions linger in our own “time when decisions are hard,” a reminder to take seriously our obligation to the future before it’s too late.