Scientists can be important public advocates in environmental issues. But scientific activism can take different forms, and deciding when and how to become an activist can be difficult for people who are trained to understand science as the objective pursuit of truth. This case study explores these issues through the history of the Oxygen Depletion Crisis. Between 1966 and 1970, it appeared that the global oxygen supply might be endangered by pesticides, industrial pollution, or the ongoing combustion of fossil fuels. The science was uncertain, but the potential threat was considerable. One response came from geophysicists Lloyd Berkner and Lauriston Marshall, who quietly initiated a research program and refrained from speaking publicly until the full scope of the crisis was better understood, in a conscious effort to avoid provoking public concern. We label this approach “public reticence.” Ecologist LaMont Cole instead made oxygen depletion a prominent talking point in his Congressional testimony and presentations across the country, so successfully stimulating the public concern that oxygen depletion became one of the multiple environmental anxieties motivating mass action on Earth Day in 1970. While the oxygen depletion crisis had a relatively clear scientific resolution, its legacy for environmental policy is interestingly complicated. This case uses historical perspective to help students to debate on scientific activism, an issue especially relevant today in light of climate change and events like the March for Science on Earth Day, 2017.

## KEY MESSAGE

Scientists can be important public advocates in environmental issues. However, deciding when and how to become an activist can be difficult for people who are trained to understand science as the objective pursuit of truth. Historical perspectives can help students explore the tensions between public reticence and scientific activism.

## INTRODUCTION

When should scientists “go public” with their concerns about potential environmental crises? What kind of danger, and what degree of scientific proof, should prompt a scientist to step outside the lab and issue a warning? And to whom should the warning be communicated: fellow scientists, policy makers, or the general public via the mass media?

Scientists have often been divided over how to answer these questions. While stimulating public concern is a common tactic for creating political or social change in a democracy, some scientists have considered advocacy to be incompatible with their commitments to be impartial and dispassionate seekers of objective knowledge. Other scientists recognize the importance of advocacy, but choose to act by doing more research to first clarify the key uncertainties [1]. They leave public advocacy for change to other groups. As climate modeler Michael Mann has described that “We scientists are, in general, a reticent lot who would much rather spend our time in the lab, out in the field, teaching and doing research. It is only the most unusual circumstances that gets us marching in the streets” [2]. But activist scientists like James Hansen see dangers in this “reticence” of scientists to write and speak publicly about environmental hazards that are not yet proven, but potentially catastrophic [3]. Events like the People’s Climate March and the March for Science in the Spring of 2017 have prompted today’s scientists to ponder their own positions on the spectrum of actions between quiet research and public activism [4].

This case study explores a historical moment when scientists debated between reticence and public activism. Between 1966 and 1970, it appeared possible—even plausible—that human activities endangered the global oxygen supply, whether due to the use of pesticides, industrial pollution, or the ongoing combustion of fossil fuels. Like some other global environmental threats, the science behind oxygen depletion was then uncertain and theoretical. In light of these uncertainties, some scientists called for more research before engaging the general public. Others sought to warn the general public through media interviews and public speeches. The existence of an oxygen depletion crisis remained a matter of scientific debate even as public anxiety about it became one of the many concerns that motivated public protest and activism in the lead-up to the first Earth Day in April 1970. The oxygen depletion story offers a way to discuss scientists’ responses to potential environmental risk with the perspective offered by historical distance.

## CASE STUDY EXAMINATION

During the 1930s, chemists and physicists began to develop a new generation of instruments for identifying and analyzing trace substances. These instruments were often faster, more sensitive, and more portable than earlier “wet chemical” methods of analysis that relied on reacting chemicals and measuring their weights and volumes. This “instrumentation revolution” helped scientists to synthesize new chemicals, identify their properties, and manufacture them in larger quantities. Although the long-term effects of these thousands of new substances were unknown, the chemical manufacturer DuPont celebrated an era of “Better Living through Chemistry” [5].

By the 1950s, some scientists suspected that some of these new chemicals posed serious short- and long-term hazards to human health and the natural environment. The United States Congress passed the “Delaney Clause” stipulating that “No additive shall be deemed safe if it is found to induce cancer in man or animal.” In 1959, advances in spectrophotometry enabled food inspectors to detect a recently developed weed killer, aminotriazole (3-AT), at concentrations below 1 ppm. Some cranberry growers had been using 3-AT to kill poison ivy between growing seasons, even though it had not been approved for use on crop lands and caused thyroid tumors in rats. Seventeen days before Thanksgiving, the Secretary of the Department of Health, Education and Welfare seized several contaminated lots and warned consumers not to eat cranberries unless they knew where their berries had come from. Restaurants changed their Thanksgiving menus, and grocers pulled cranberries off the shelves. Cranberry growers were outraged. Presidential candidate Richard Nixon defiantly ate four servings while campaigning in Wisconsin. Though ultimately <1% of total cranberries tested were found to be contaminated, the cranberry industry announced that it had suffered US$40 million in losses. Advocates for the chemical industry called it “The Cranberry Scare” and recounted the story to show the ridiculousness of worrying too much about trace chemicals ([6, 7]: pp. 67–68, [8]). While the Cranberry Scare was at its scariest, the bestselling nature writer Rachel Carson was working on a book explaining the dangers of pesticides. Carson was an experienced biologist who brought together numerous ecology studies showing that pesticides harmed fish, birds, wildlife, and livestock. Chlorinated hydrocarbons including DDT did not readily break down in the environment. They became concentrated in larger vertebrates, spread into the ocean, and could even be detected in human breast milk [9]. Published in 1962, Silent Spring stimulated national scientific and political debate over the harms that pesticides could cause, leading to new government regulations and a changed sense of responsibility among some scientists [10]. As one committee of ecologists argued “Silent Spring created a tide of opinion which will never again allow professional ecologists to remain comfortably aloof from public responsibility” [11]. The chemical industry’s reaction was swift and vicious. The National Agricultural Chemicals Association spent well over US$250,000 to stimulate public skepticism toward Carson’s work. Public challenges focused on Carson’s gender, her lack of a Ph.D., and her lack of a job as a research scientist. Other attacks labeled her an alarmist, emphasizing the social discord and worry that her words would cause. A review in Time magazine accused Carson of taking up her pen “in alarm and anger, putting literary skill second to the task of frightening and arousing her readers” (Time 1962 [12]; quoted in Lear [10]: p. 403). A nutrition scientist connected to the food and chemical industry writing in the Boston Morning Globe castigated Carson for “arousing an apathetic, unscientific public” and “abandoning scientific proof and truth for exaggeration” (Stare 1963 [13]; quoted in Lear [10]: p. 433). Former Secretary of Agriculture Ezra Taft Benson called Carson “probably a communist,” a potent slur in Cold War America ([10]: p. 429).

For a small subset of scientists, Silent Spring raised a more existential worry. Geophysicists Lloyd Berkner and Lauriston Marshall had recently theorized about the crucial role that photosynthetic marine algae played in creating the Earth’s breathable oxygen [14, 15]. If DDT or another new chemical harmed oxygen-producing marine organisms, then humans might inadvertently disrupt the planet’s oxygen supply. Studies had already detected the high levels of herbicides and insecticides in oceanic fish caught around Newfoundland, which seemed like an ominous development. What should scientists do?

Berkner and Marshall chose to write private letters, in an effort to start a quiet research program that would measure atmospheric oxygen levels. Unlike many ecologists including Rachel Carson, Berkner had advised presidential administrations and worked on sensitive projects connected to national security and nuclear weapons [16, 17]. Marshall had also been involved with military and nuclear research [18]. Given their ties to government and military circles, they wrote in 1966 to President Lyndon Johnson’s science advisor, and to Robert White, the head of the government’s Environmental Science Services Administration (ESSA), citing the Newfoundland fish study and describing oxygen deprivation as a “nasty ecologic problem” [19]. The Johnson Administration agreed to fund a 3-year study to collect oxygen samples around the globe and compare them with the records from 1910. Two researchers, meteorologist Lester Machta of the Environmental Science Services Administration and chemist Ernie Hughes from the National Bureau of Standards, were chosen to conduct the study. In the meantime, “out of fear of public reaction and perhaps improper action concerning a serious problem whose reality has not yet been numerically identified,” Berkner and Marshall advocated public reticence [19].

Ecologist LaMont Cole felt that a much louder response was needed. One of America’s most distinguished ecologists, Cole had been inspired by Rachel Carson’s activism. ‌ He thought that it was just a luck that one of the untested new chemicals had not yet caused catastrophic effects [20, 21]. Testifying before Congress in 1966, Cole worried that “we are close to the critical point” where the rate of combustion of fossil fuels would exceed the rate of photosynthesis, while calling for more research and acknowledging that “satisfactory data of the necessary sort do not exist” [22, 23]. What was known, however, was sufficient to justify some degree of alarm. Laboratory experiments and field observations in Long Island Sound had shown that DDT concentrations as low as a few parts per billion reduced photosynthesis in species representing four major classes of algae. “This inhibition may be of ecological importance,” noted biologist Charles Wurster [24]. The apparent effects of DDT on oxygen levels paralleled Cole’s own concern that the rate at which industrialized nations burned fossil fuels may have already exceeded the global rate of photosynthesis [22, 23].

Cole’s public activism provoked a range of responses from the media and other scientists. He was invited to speak at campuses across the country and was interviewed by major news organizations, helping to make the oxygen deprivation crisis a subject of national concern. The editorial staff of the Biddeford-Saco Journal in small town Maine asserted that Cole’s public alarm about the oxygen crisis reinforced a sense of fear and resignation: “Americans do not have enough problems, it seems. There is a war in Vietnam, strife at home, and water pollution. Now a scientist says the country is running out of air to breath—even smog-filled air” [25]. Time magazine dismissed him as one of the “tiny band of ecologists,” these “new Jeremiahs” and “doomsayers” who predicted destruction [26]. John Ryther, a senior scientist at Woods Hole Oceanographic Institution, worried that public declarations about the oxygen deprivation crisis were inducing “near-hysterical alarm” [27].

Popular concern about the environment was certainly growing. Environmental activism reached a crescendo with about 20 million Americans participating in Earth Day activities on April 22, 1970. Earth Day was not one national event but 12,000 or 13,000 locally organized events, reflecting a range of local, national, and global environmental concerns. Some of the events were symbolic gestures like the Dead Orange Parade through Miami. Others built upon existing activist groups in ways that transformed the dynamics of local environmental politics. Educators organized teach-ins at universities and pollution-themed lessons in public schools; city governments featured their anti-pollution agencies at public events; and local community groups rallied support for reducing smog, cleaning polluted water, or collecting litter. Political observers noted the large number and the diversity of people motivated to action by environmental anxiety ([21]: pp. 116–164).

While the public clamored for environmental protection, Machta and Hughes were finishing their oxygen study. They compared observations from 1910 with 78 air samples taken between 1967 and 1970, analyzed using a Beckman Instruments model E4 Oxygen Analyzer, sensitive to “five or six significant figures” [28]. They found either no change or changes lower than the uncertainty in the measurements. In an article published in Science at the end of June 1970, Machta and Hughes explained these results ran counter to “several ‘doomsday’ predictions” promulgated in the media [29]. In a published letter that coincided with Machta and Hughes’s study, geochemist and geophysicist Wallace Broecker wrote that concern about the oxygen supply appeared “in almost all grocery lists of man’s environmental problems.” With “so many real environmental crises” beyond the phantom oxygen crisis, Broecker hoped the popular press would now “bury the bogeyman it created” [30].

While the results of their study made the potential oxygen crisis less pressing, Machta and Hughes could not undo the attention and anxiety it had already generated in the public sphere. Some newspapers did run stories about Machta and Hughes’s study, but the press did not “bury the bogeyman.” It is probably more accurate to say that the oxygen crisis faded from public consciousness as prominent scientists stopped talking about it and science reporters moved on to more urgent topics, such as protecting endangered species, and legislation banning DDT in 1972.

## CONCLUSION

Americans felt anxious about the potential risks to their health and to the environment in the decades after World War II, thanks to episodes like the Cranberry Scare of the late 1950s and the DDT controversy in the late 1960s, not to mention the well-publicized harms caused by things like the anti-nausea drug thalidomide and radioactive fallout [31]. These anxieties were attributable to many sources, including over-confidence in technology, undertested new substances, and irresponsible actors within industry and government. The oxygen depletion crisis highlighted how environmental scientists could contribute to public anxiety through their public activism.

Since Machta and Hughes had shown empirically that oxygen levels were not going down, and that humans were in no immediate danger of running out of oxygen, one could easily interpret their results as a vindication for the more reticent posture advocated originally by Berkner and Marshall. Even so, Machta and Hughes’s findings were not inconsistent with the theory that free oxygen levels should decrease as fossil fuels were burned. In fact, researchers have since developed a more sensitive technique to measure oxygen levels out to the seventh significant figure, finding that atmospheric oxygen is indeed diminishing [32, 33].

LaMont Cole experienced a significant professional backlash for his decision to “go public” and stimulate public anxiety about oxygen depletion. In addition to being chastised by some geophysicists, Cole was denied the high honor of membership in the National Academy of Sciences, as was Barry Commoner, another prominent activist scientist. Philip Handler, the nutritionist and biochemist then serving as president of the NAS, emphasized the value of public reticence in explaining his decision: it “behooves a scientist to be even more sure of his facts when speaking before the public than before a scientific body” [34].

But what other standards of conduct could scientists have adopted, if not Berker and Marshall’s public reticence or Cole’s highly visible environmental advocacy? As with any worldly matter, how scientists choose to communicate in a political environment constitutes a vast grey area of possibility [35]. Climatologist Stephen Schneider framed the challenge as a “double ethical bind,” one wherein scientists consider how best to “balance between being effective and being honest” [36]. To manage this dilemma, scientists have chosen from an array of options: to publicly acknowledge their own ethical values; explicitly distinguish their political views from their technical evaluations; or try to advise in a manner that is both ethically informed and scientific while working within the system [37, 38].

While the landscape of environmental politics has shifted since the late 1960s, scientists still confront the challenges of public communication and political advocacy. Scientists’ concerns about being called alarmist have interacted with politics to shape climate change communication in influential ways. In the case of assessing the impacts of the melting of the West Antarctic Ice Sheet, for instance, scientific assessment reports have been biased toward cautious estimates rather than more severe potential effects. This bias toward “erring on the side of least drama” may make it difficult to recognize and respond when dramatic changes in natural phenomena actually do occur [39]. Other scholars have noted how efforts by fossil fuel interests to cast doubt upon climate science have created a tendency to over privilege uncertainty-based arguments even when scientists know these arguments are misleading [40]. Some scholars have even turned to science fiction to warn present generations of the far-reaching consequences of global warming, most visibly represented in a new literary subgenre: climate fiction [41, 42].

In terms of policy, there is ample evidence to suggest that inducing public alarm has inspired the creation of international treaties to monitor and regulate the influence of CFCs on the ozone layer, as well as the creation of accords to manage the risks of climate change. Indeed, important policy changes resulted from public anxiety about environmental degradation raised by stories including the oxygen deprivation crisis. Earth Day’s massive display of public activism helped to ensure that Congress and President Richard Nixon acted on environmental protection. Without the public pressure generated in part by emotional anxieties, Nixon probably would never have created the EPA or signed the Clean Air Act in 1970 and the Clean Water Act in 1972, thus establishing a new institutional stronghold for environmental science within the federal government [43]; nor would his and subsequent administrations have incorporated the risks of environmental change into international diplomacy [44]. These actions will save many lives in the decades to come—plant and animal as well as human.

## CASE STUDY QUESTIONS

1. What lessons do you think scientists today should take from the story of the oxygen depletion crisis?

2. How is climate change comparable to the oxygen depletion crisis? In what ways is it different? Can this story help us to think about more wisely about other environmental crises?

3. In what ways were Berkner and Marshall also being “activist scientists” as they initiated further research? How did the results of their activism differ from the activities of Cole?

4. How do you think the magnitude of the potential crisis should affect a scientist’s decision about speaking out? Does a potential global catastrophe require more—or less—solid scientific proof than a smaller problem before going public?

5. Do you think having specialized scientific skills imposes a different set of obligations upon a scientist, compared with other people? What kinds of responsibilities come with the power to measure?

## AUTHOR CONTRIBUTIONS

This article was jointly written by the authors. Both authors drafted original text and made revisions throughout the case. The case emerges from the confluence of research conducted by both authors. Gabriel Henderson researched the oxygen depletion crisis as part of his dissertation on the politics of climate science between the 1960s and 1980s. Roger Turner’s research focuses on atmospheric science and scientific instrumentation during the twentieth century.

## COMPETING INTERESTS

The authors have declared that no competing interests exist.

## SUPPLEMENTARY MATERIAL

Teaching notes. Doc

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