Environmental Effects of Acid Rain: The Tense Debate

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What are the issues in the debate about the environmental effects of acid rain? What’s the science and what doubts exist?

In Merchants of Doubt, historians Naomi Oreskes and Erik Conway discuss how doubt-mongering has affected the debate surrounding the environmental effects of acid rain. It’s a fascinating history of science, economics, and politics.

Read more to learn how merchants of doubt impacted the narrative about the environmental effects of acid rain.

Discovery of the Environmental Effects of Acid Rain

Anthropogenic (human-caused) acid rain was first discovered in North America during the pollution prevention era of U.S. environmentalism, but by the time it was well-studied years later, the government had moved away from prevention and regulation, which made it hard for scientists to spur policy action.

People first discovered natural acid rain (caused by volcanoes) in the Renaissance, and scientists discovered anthropogenic acid rain in the 19th century. Acid rain appeared to be a local phenomenon—it fell close to the pollution sources, such as factories and cities and central Germany, that caused it. No one had seen it in North America before. Certainly, no one understood the environmental effects of acid rain.

Then, in 1963, Gene Likens and three other scientists discovered acid rain in a remote, experimental forest in New Hampshire called Hubbard Brook. There were no nearby sources of pollution, but the rain had a pH of 4 or less. (pH is a measure of acidity; the lower the number, the more acidic the substance, and each integer represents a tenfold increase from the previous increase. Normal rain has a pH of approximately 5, so the Hubbard forest’s rain was 10 times more acidic than regular rain. One sample even had a pH of 2.85, which is about as acidic as lemon juice.)

The scientists determined that the forest’s acid rain was created when sulfur and nitrogen (released by burning coal and oil) mixed and dissolved in water in the atmosphere. The sulfur and nitrogen wouldn’t necessarily fall as precipitation right away—they could travel through the atmosphere and fall far away from their source. The acid rain in the experimental forest had been falling for around 20 years and was related to pollution stemming from the Midwest.

Why Now?

People had been burning fossil fuels since the 1850s, but anthropogenic acid rain hadn’t been falling for that long (for example, Hubbard Brook had only been experiencing it since the mid-20th century). This was because, in the 1950s, plants and factories introduced two new technologies:

  • Installed “scrubbers,” which remove the particles from emissions. Particles are especially dangerous to the human respiratory system—for example, in 1952 in London, the smog was so bad many people died from it.
  • Built taller smokestacks so that the pollution would disperse over a wider area rather than falling in high concentrations near the factories.

These technologies helped with particle and local pollution, but they also contributed to the creation of acid rain. The particles in emissions, while dangerous to people, neutralized acid. Once they were scrubbed out of the emissions, the pollution stayed acidic. Additionally, the combination of fewer heavy particles and higher smokestacks meant that the pollution could travel farther from its source.

Potential Effects

In 1974, Gene Likens submitted a paper to Science that explained this discovery and concluded that acid precipitation was falling on a large part of the northeastern U.S. The potential environmental effects of acid rain included:

  • Nutrient leaching (The acid in the rain chemically reacts with nutrients in soils and foliage, using them up so they’re no longer available for plants.)
  • Corrosion of architecture
  • Acidification of water bodies
  • Damage to wildlife (Shortform example: Acid rain can dissolve oyster shells.)

However, it was too early to say if any of these effects were actually happening yet.

Further Exploration of the Science

While Likens and his colleagues couldn’t prove that the environmental effects of acid rain were actually a problem or were already underway, other studies had also found some early warning signs. This science was mainly published in government reports (in the official languages of the government’s country) and specialized journals, so most journalists, politicians, and the public would never read them. 

In 1976, Likens summarized everything that was known so far—that acid rain was damaging, far-reaching, and could cross borders—in Chemical and Engineering News. Likens’s article clearly said that acid rain was a problem, but the magazine sowed doubt—it included a caption that suggested that the cause wasn’t entirely clear, and neither were the consequences. 

Here’s what was clear at this point:

  • Acid rain was definitely real and caused by increasing sulfur emissions.
  • The fish and forests were suffering.

Here’s what was still unknown:

  • How damaging the rain was
  • How the sulfur moved around the atmosphere 
  • Whether the smokestacks were the problem or just fossil fuel burning in general (which was increasing)
  • How much of the sulfur was anthropogenic

Was Acid Rain Caused by Humans?

The environmental effects of acid rain were becoming clearer. Another question remained: Are humans to blame? If acid rain was caused by naturally occurring sulfur, there would be no point in regulating human emissions of sulfur because they weren’t actually responsible for causing acid rain. Therefore, an important next step was figuring out if the sulfur was anthropogenic.

Scientists did this in two ways:

1. Mass balance. Meteorologist Bert Bolin and his colleagues considered the two major naturally occurring sources of sulfur—volcanoes and sea spray—and then compared how much these sources produced to how much sulfur was falling in acid rain in Sweden. Northern Europe doesn’t have any active volcanoes, so they weren’t responsible for the sulfur. Sweden does have sea spray, but it doesn’t travel very far, so it couldn’t be a source inland. Therefore, a lot of the sulfur had to come from pollution, because there was nothing else that could have produced it in such large quantities.

2. Isotopes. Isotopes are heavier or lighter versions of the same chemical element. Their weight can be used like a “fingerprint”—for example, the sulfur isotope sulfur-34 appears in different quantities in different sources (volcanos have a different amount of sulfur-34 than car exhaust). Measuring the amount of the isotope present can tell scientists where the sulfur in acid rain comes from. 

  • For example, one study found that the sulfur in acid rain in Sudbury, Ontario, was the same type of sulfur as what was in the local mines.

Evidence of Nutrient Leaching

In 1979, geologist Noye Johnson shed more light on the environmental effects of acid rain when he published evidence of nutrient leaching at Hubbard Brook in scientific journals. Interestingly, though acid rain was falling on the forest, the streams weren’t acidic. Johnson and his team found that this was because of nutrient leaching—when the rain moved through soil, the acid reacted with nutrients. These reactions (and destruction of nutrients) neutralized the rain so that water running into the streams was a normal pH.

Announcing Discoveries to the Public

In October 1979, after acid rain had been studied for almost a quarter-century, Likens and his colleagues wrote a piece for Scientific American, which is aimed at the public. There was no uncertainty in the article or from the magazine’s editors about the environmental effects of acid rain.

Policy and Public Action

In November 1979, the Convention on Long-range Transboundary Pollution passed by the UN Economic Commission for Europe said that it was illegal for a country’s pollution to affect another country. This meant that the signatories would have to address atmospheric emissions, including sulfur. 

Also in 1979, the U.S. and Canada issued a Joint Statement of Intent to reduce emissions and therefore cross-border pollution and acid rain. Environment Canada had found that over half of the acid rain in Canada was created by pollution in the U.S.

In 1980, Carter signed the Acid Precipitation Act of 1980, which kicked off a 10-year research program on sulfur and nitrogen oxides. He also created a committee and started negotiations with Canada to work together scientifically and politically on acid rain. Canada and the U.S. signed a Memorandum of Intent—both countries would:

  • Enforce pollution laws.
  • Contribute scientists to working groups that would determine if stronger regulations were needed.

The MOD’s Response

In 1980, Reagan was elected and his views—deregulation, a hands-off government, and prioritizing private enterprise—conflicted with the acid rain science. He and the merchants of doubt were concerned by the memorandum of intent and the U.S.-Canadian working groups.

In 1982, Reagan, via the White House Office of Science and Technology Policy (OSTP), called for a review and summary of the working group’s work (which wasn’t completed yet). This seemed unnecessary because the science around acid rain was well-studied by this point—the National Academy of Sciences (NAS) had already done a review of the existing literature in 1981, concluding that acid rain was dangerous and needed to be addressed by reducing emissions. An Environmental Protection Agency (EPA) report concurred.

The OSTP created the Acid Rain Peer Review Panel to do the review and summary and chose William Nierenberg to chair it (possibly because he’d just wrapped up a report about the effects of carbon dioxide on climate that found everything was fine and the only thing to do was more research). 

Nierenberg’s panel included several respected scientists including Sherwood Rowland, who had shared a Nobel Prize in chemistry for his work on the ozone hole (see Chapter 7), and Gene Likens. It also included S. Fred Singer at the White House’s suggestion.

At the beginning of 1983, the panel determined that they would include everyone’s point of view, however dissenting, in the summary, and it would be jointly authored. There would be no appendices.

Further Exploration of the Science

In 1983, the U.S. and Canadian working group’s reports found three critical pieces of information:

  • Acid rain had been damaging large parts of North America for decades.
  • Acid rain was caused by anthropogenic emissions and long-range atmospheric transport.
  • Both countries should be invested in stopping the pollution because it was crossing the border in both directions.

Their suggested fix was to use the technology that already existed to reduce emissions. If emissions weren’t reduced, the problems would get worse. 

(The reports weren’t as explicit about these three pieces of information as they could have been. Scientists, like MODs, tend to emphasize uncertainty, though for different reasons—focusing on uncertainty is what pushes science forward.)

Most of the text of the U.S and Canadian reports was the same—“agreed text”—but the U.S. report found greater uncertainty in the cause-and-effect relationship between pollution and acid rain. (The Canadians probably were more motivated than the Americans to take action on acid rain because much of their economy depended on forests and fish. The Americans were probably less keen because most of the pollution was coming from the U.S., so they would have to pay for the cleanup.)

The MOD’s Response

It would take over a year for Nierenberg’s panel to release their summary of the working groups’ report. Most of the panel found that the working group’s work was thorough and that acid rain was understood well enough to justify action now. There were uncertainties, but they were details, and if we waited until those were all settled (potentially 50 years in the future), too much damage would have happened in the meantime.

Singer didn’t see it like this. As the panel reviewed the science and wrote their summary, Singer:

  • Regularly brought up uncertainties and costs, the same concerns of the electric power industries who produced many of the emissions. 
  • Circulated evidence that acid rain wasn’t affecting tree growth
  • May have circulated a document criticizing the National Academy of Sciences’s review because, among other things, it didn’t consider economic effects (which had never been within its scope)
  • Suggested that other pollution was more dangerous than acid rain
  • Argued that if there was no way to prove the value of the environment, then it was worthless
  • Brought up market-based solutions even though the committee’s role wasn’t to suggest fixes; it was just to summarize the findings of the working groups. He argued that the market and the laws of supply and demand would naturally sort out pollution problems so no regulation was needed. For example, as the price of oil increased, supply would increase, driven either by extracting more oil or people choosing to use other less expensive fuels.
  • Tried to make it seem like the committee was divided on the issue. (They were only divided in that everyone disagreed with Singer.)
  • Wrote the chapter about how to calculate the economic benefits of acting on acid rain

An Early Draft of the Summary

In March 1983, the summary was almost ready. John Robertson, who was compiling the report and putting together changes, sent the latest draft to the panelists. However, there were more revisions needed—the rest of the panelists didn’t agree with what Singer had written.

Singer’s chapter didn’t actually include any of the cost-benefit analysis he’d insisted was necessary. (He said the numbers were too hard to quantify. In fact, it is possible to assign value to nature—the White House Council on Environmental Quality had put a number on the air quality benefits stemming from the Clean Air Act—$21.4 billion a year.)

Instead, Singer’s chapter said:

  • Nature had no value, so protecting it would have no economic benefit. Doing nothing would be free and have the same economic effect. 
  • There are many sources of pollution, so addressing one might not create any immediate benefit, particularly because pollution control is often only applied to new sources, not old ones. (Singer did acknowledge that regulations should apply to all sources, otherwise there would be no incentive for progress).
  • The cost of reducing acid rain would be incurred in the present, but any benefits wouldn’t be realized until the future, so the math had to be adjusted for that by “discounting.” (A dollar in the present is more valuable than a future dollar due to inflation and the value of the future.)
  • The best way to solve the problem was the market-based approach of transferable emissions rights, or cap-and-trade. (This approach would be used later for acid rain, but Singer didn’t analyze the details or provide a successful case study.)

Singer’s chapter ended with a question that implied that reducing emissions wouldn’t have a proportional reduction in acid rain.

The rest of the panel didn’t agree with his conclusions because they’d found:

  • There were ecological costs, so the relevant cost-benefit equation was how much to spend to mitigate them.
  • There would be an immediate benefit to addressing the environmental effects of acid rain. Acid rain was mainly caused by sulfur dioxide and if emissions were cut by a quarter, there would quickly be environmental improvements. Additionally, it was possible to apply pollution control to both old and new sources of sulfur dioxide emissions.

An Interim Update

In June 1983, the White House Office of Science and Technology Policy (OSTP) asked for an interim update. The panel put together the first draft of a press release which clearly stated that the U.S. and Canada collectively emit over 25 million tons of sulfur dioxide a year and that while scientists would prefer more certainty, there was enough known to start searching for solutions now. There were two particularly striking points: 1) the existing damage might take decades to repair, so it was fair to call it irreversible, and 2) soil damage could unbalance the food chain.

The OSTP sent back the press release with suggested revisions that weakened it. The two paragraphs about irreversible damage and soil damage were dropped, and the other paragraphs were reordered so that the press release no longer started with the emissions numbers. Instead, the release started by discussing what had already been done under the Clean Air Act and the uncertainties.

Another Draft of the Summary

Robertson provided a new summary draft in July 1983. This version also didn’t become final—the panelists still didn’t agree. Singer suggested revisions that implied that acid rain wasn’t that bad and was too expensive to fix. For example, a sentence in the report said that there was a need to understand the ecological consequences, Singer added the word “economic,” so it read “ecological and economic consequences.”

Another Interim Update

In September 1983, the panel’s vice chair shared interim conclusions with the House of Representatives Committee on Science and Technology. Singer wrote to the committee chair to complain that the vice chair’s claims were unsupported. Singer argued that there wasn’t enough information, brought up true but irrelevant information, and made it seem like the panel was divided when in reality, everyone agreed except Singer. 

The “Final Draft”

Another draft of the summary was ready in February 1984. This was the last draft most of the panelists saw and they had different opinions on how to handle Singer’s chapter. Some wanted to demote it to an appendix that was signed by Singer (the rest of the report was jointly authored, as had been agreed on and was the norm); others would accept it as a chapter if Singer revised it. Robertson input changes in March and made three copies of the final report, one for himself, Nierenberg, and the White House OSTP. The OSTP received the report in April.

The White House suppressed its release because they didn’t want to spur policymakers into action—in April, an important House subcommittee was considering acid rain legislation).

In May, the OSTP asked Nierenberg to:

1. Change Singer’s chapter to an appendix. If Singer was the sole author of an appendix, the rest of the panel wouldn’t have to sign off on it. 

2. Revise the Executive Summary. The OSTP asked to start with a description of the panel’s formation instead of the realities of the environmental effects of acid rain. The OSTP also wanted the sections about the dangers and causes of acid rain moved to the next-to-last paragraph. 

It’s normal for the leader of a panel (in this case, Nierenberg) to meet with the organization that commissioned the panel’s report (in this case, the OSTP) and present the final report to government officials. What’s not normal is for an official to ask for changes. However, Nierenberg did ultimately make the changes without informing all the panelists. 

Publishing the Summary

The summary was finally released in August 1984. One of the panelists, atmospheric chemist Kenneth Rahn, realized that someone had made changes without running them by the panel first. He thought the changes were so substantial that the panel wouldn’t have approved them if they’d been consulted. 

The Canadians weren’t impressed that the summary was so much weaker than the actual working group’s reports and asked the Royal Society of Canada to do their own review. The Royal Society found that the U.S. and Canada’s reports agreed on most things, but the U.S. summary was quite different from the actual reports. While there were uncertainties, the reviewers thought what was known was enough to take action. 

Policy and Public Action

In 1984, Congress axed the joint pollution control program. No acid rain legislation would go into effect during Reagan’s term because the MODs continued to claim that the cause of acid rain was still unknown and fixing it would be too expensive.

Setting the Record Straight

Likens tried to get the truth out. He published articles in niche scientific magazines, but mass media, especially pro-business publications, promoted Reagan’s view and ignored or missed the real science. For example:

  • Soil scientist Edward Krug found that soil acidification in the northeastern U.S. was caused by land-use changes or natural phenomena. Scientists had already considered natural acidification and determined that it wasn’t significant enough to produce the numbers, but Krug’s science was widely publicized. 
  • Fred Singer published an article about how the inaction had saved money.
  • Fortune claimed that the environmental effects of acid rain was minor.

As a result of all this conflicting press, the public thought that acid rain wasn’t well understood and that the issue was still in debate. Even Naomi Oreskes, the co-author of Merchants of Doubt, taught the acid rain debate as part of an earth science class at Dartmouth and used Krug’s work as a reference.

Further Scientific Exploration

People had kept researching the environmental effects of acid rain, and in 1989, the World Resources Institute’s Mohamed El-Ashry said that the last 10 years of research had just confirmed what was already known. 

Policy and Public Action

It wasn’t until 1990 that the Clean Air Act was amended to control sulfur emissions using a cap-and-trade system.

The cap-and-trade system was effective and inexpensive—between 1990 and 2007, sulfur dioxide emissions reduced 54% and the price of electricity went down (after being adjusted for inflation). The Environmental Protection Agency (EPA) reported that from 1993-2003, pollution control cost $8-9 billion and the benefits were worth $101-119 billion. All of the economic disasters that the industry claimed would befall the world if the environment were protected—costs, job loss, electricity price increases—didn’t happen.

Cap-and-trade is widely viewed as a success, and it could be effective for other types of pollution, but scientists aren’t sure if it’s actually worked in the case of acid rain. The 1990 caps were too high (which might have been influenced by Singer and Reagan’s claims that since there was uncertainty, it would be smartest to only take modest steps) and acid rain still exists and may still be damaging the environment at the same rate.

Further Scientific Exploration

Scientists, including Gene Likens, kept studying the experimental forest where they had discovered acid rain. In 1999, Likens wrote that acid rain still existed, and forests were even more susceptible to it because global warming was additionally stressing them. The forest no longer grew. A decade later, they wrote that the forest hadn’t grown since 1982 and had been significantly shrinking since 1997.

Scientists and policymakers have long discussed the environmental effects of acid rain, and it is important to understand how merchants of doubt have been part of the debate.

Environmental Effects of Acid Rain: The Tense Debate

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Elizabeth Whitworth

Elizabeth has a lifelong love of books. She devours nonfiction, especially in the areas of history, theology, science, and philosophy. A switch to audio books has kindled her enjoyment of well-narrated fiction, particularly Victorian and early 20th-century works. She appreciates idea-driven books—and a classic murder mystery now and then. Elizabeth has a blog and is writing a creative nonfiction book about the beginning and the end of suffering.

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