Atmospheric Chemistry Research that Changed Global Policy: _{The work of Mario Molina}

Science for the good of society

Molina’s interest in science began when he was a child, first reading biographies of famous scientists and later progressing to the thrill of observing amoebas and paramecia with his own toy microscope. As he became more sophisticated, he converted a little-used bathroom into a laboratory, where with guidance from his chemist aunt, Esther Molina, he was able to do college-level experiments when he was just 11 (Nobel Prize Organization, 2011).

After high school and college in Mexico and graduate studies in Germany and France, Molina entered a PhD program at University of California Berkeley. Molina recalls his years at Berkeley as some of the best in his life. The research was exciting, and the environment was intellectually stimulating. In the 1960s and 1970s, Berkeley was a major seat of unrest over the Vietnam War and a center for radical ideas. Molina’s research project, which involved chemical lasers, did not sit well with student activists. The socio-political climate at Berkeley caused Molina to think hard about the impact of science on society for the first time. In an autobiographical essay for the Nobel Foundation, he reveals:

I was dismayed by the fact that high-power chemical lasers were being developed elsewhere as weapons; I wanted to be involved with research that was useful to society, but not for potentially harmful purposes. (Molina, 2007)

After graduating from UC Berkeley, Molina was able to pursue a project that did not conflict with his evolving ideology when he became a postdoctoral student at UC Irvine. His advisor, F. Sherwood “Sherry” Rowland, was interested in exploring a new direction as well. Of the possible projects that Rowland suggested, one in particular piqued Molina’s interest. Rowland thought it might be worth looking more closely at chlorofluorocarbons, or CFCs, which were released into the atmosphere from a vast array of consumer products. These chemical compounds are inert in the lower atmosphere; that is, they do not react with other chemicals. Embraced for their safety and stability, CFCs were used in products from coolants to Styrofoam to aerosol sprays. Molina was immediately drawn to the project, seeing the practical implications.

Together, Molina and Rowland embarked on a voyage of discovery to answer the question: “What happens when society releases inert gases to the atmosphere?” Within three months, they realized that this was not just a scientific question but a potentially serious environmental problem concerning substantial depletion of the ozone layer. What they discovered, in Rowland’s words, was that “[e]ntire biological systems, including humans, would be at danger from ultra-violet rays” (Wilson, 2012).

Molina continued his research while Rowland was in Vienna on spring sabbatical. In a frenzied back-and-forth of phone calls and letters, the two refined their theory of ozone depletion. In the early months after making the CFC-Ozone connection, Rowland’s wife reportedly asked how the research was going. Rowland answered, “It’s going very well. It just means, I think, the end of the world” (Jones, 1988).

CFCs: Miracle compounds

CFCs had become extremely popular long before Molina and Rowland chose to focus on these chemicals; in fact, they were a fixture among consumer products even before Mario Molina was born. In 1935, the DuPont chemical company adopted the slogan “Better things for better living… through chemistry,” and nothing seemed more genuine than the promise of those words. Four years earlier the company had discovered chlorofluorocarbons, or CFCs for short, and launched them under the trade name Freon. These miracle compounds promised to be a safe and environmentally friendly alternative to the refrigerants used at the time, which had a bad track record of being flammable, corrosive, and toxic – even fatal – to humans.

By 1938, Freon had captured 15 percent of the refrigerant market, and was steadily growing. Then DuPont found that Freon was an ideal propellant, and by 1968 annual sales of CFC-powered aerosol cans reached a staggering 2.3 billion (Fisher, 1990). The commercial success and potential new applications for CFCs seemed unstoppable. That is, until Molina and Rowland claimed in a 1974 Nature article that these seemingly benign products that had swept the globe would eat away at Earth’s protective ozone layer, exposing humans and other living things to potential harm from radiation (Molina & Rowland, 1974).

Molina considered how CFCs would not be removed from the atmosphere by natural reactions because they were inert but rather over several decades would continue to migrate upwards through diffusion until they eventually reached the stratosphere. The stratosphere is the layer of Earth’s atmosphere that begins about 8 to 16 km (5 to 10 miles) above the planet’s surface. In the lower stratosphere sits the ozone layer, a belt of concentrated ozone gas (O₃) that absorbs much of the sun’s dangerous ultraviolet radiation (Figure 4). The thinner the ozone layer, the more ultraviolet B (UVB) rays reach the Earth’s surface, leading to skin cancer, cataracts, and weakened immune response in humans, as well as damage to marine ecosystems, plants, and certain materials (EPA, 2010).

Since no natural processes would remove CFCs from the atmosphere, Molina proceeded with knowledge of how diffusion works. Examining the weight of CFC molecules when compared with other compounds in Earth’s atmosphere, Molina estimated how long it would take CFCs to reach the stratosphere given their estimated lifespan of 40-150 years. He and Rowland posited that once CFC molecules reached the ozone layer, ultraviolet radiation would break apart the molecules, freeing chlorine atoms. These free chlorine atoms up in the stratosphere were not inert, however – they would react with ozone molecules with destructive effects (Molina & Rowland, 1974).

Molina calculated the chemical reactions that would occur once the CFC molecules were dissociated by ultraviolet radiation. In chemistry, the term dissociate means to break down a molecule into atoms or simpler molecules, freeing them to recombine in new ways. Molina looked more closely at what the chlorine (Cl) atoms would do once they were liberated from the CFC molecule. He discovered a potentially disastrous impact on the ozone layer.

Sobering calculations

How might the ozone layer be affected by the CFCs once they were broken apart in the stratosphere? Molina’s model predicted that the chlorine atoms (Cl) that broke free from the chlorofluorocarbons would react with ozone molecules (O₃), forming a chlorine-oxygen compound (ClO) and molecular oxygen (O₂):

Molecular oxygen also breaks down in the stratosphere, producing solitary oxygen atoms (O):

Although Cl reacts to form ClO, single chlorine atoms (Cl) are also produced when ClO reacts with the oxygen atoms that are formed when molecular oxygen is dissociated (see the reaction above). Thus:

In other words, chlorine atoms react to break apart ozone molecules, but they are still around after ozone has been broken down so they can destroy more ozone. This means that chlorine serves as a catalyst for the reaction of ozone with atomic oxygen: It produces O₂ while the chlorine itself is not affected. Thus, chlorine atoms can cause extensive damage to the ozone shield over the long term. In fact, each single chlorine atom that breaks free can destroy more than 100,000 molecules of ozone (Fisher, 1990).

Rather than designing a lab experiment to explore their hypothesis, Molina and Rowland used their knowledge of chemistry to build a model to predict what could – and did – happen. This is an example of prescriptive modeling, a method commonly used by scientists. In prescriptive modeling, scientists take the information they already have about the way the universe works to make predictions about what can occur if x and y happen.

A journal article that would change the world

Molina and Rowland published their findings in a three-page article titled “Stratospheric sink for chlorofluoromethanes: Chlorine atom-catalysed destruction of ozone” in the June 1974 issue of Nature. They pointed out that there were enough CFCs around to decrease the ozone concentration in the protective layer by several percent, a significant decline (Molina & Rowland, 1974). To put the number in perspective, Harvard researchers report that for each fractional decrease in the ozone layer, the incidence of skin cancer increases threefold (Harvard University, 2012).

Three months later, other scientists corroborated Molina and Rowland’s findings in print. In a September 1974 article in Science, University of Michigan researchers claimed that ozone would be displaced downward as early as 1985 (Cicerone, Stolarski, & Walters, 1974). That same week, the New York Times ran a front-page story on research by Harvard scientists Michael B. McElroy and Steven C. Wofsy, who also arrived at calculations that supported Molina and Rowland’s claims and argued that ozone layer reduction could be as large as 3 percent by 1980 and 16 percent by 2000 (Sullivan, 1974).

For Molina and Rowland, it was not sufficient to keep their findings within the scientific community. Given the seriousness of the issue, they realized that the only chance of the problem being addressed was to share their results with the media and policymakers. They talked to journalists, published more articles on the issue, presented at conferences, and testified at legislative hearings (Molina, 2007).

There was severe backlash from industry. Even the scientific community was skeptical. Molina and Rowland had essentially created a new discipline – atmospheric chemistry – and their calculations were not yet borne out through observation. Since it takes decades for CFCs to migrate upwards to the stratosphere, Molina and Rowland were talking about damage that would happen in the future. Rowland noted a definite distancing by the scientific community, evidenced by an absence of speaking invitations for the entire decade after the Nature article was published. But the snub didn’t bother him because he knew they were right (Barringer, 2012).

Hard evidence finally arrived in the 1980s – 11 years later – when British scientists confirmed an extreme thinning of the ozone layer over the South Pole that appeared in the Antarctic Spring (around October). The “ozone hole” began appearing every year, measuring a 20 percent depletion in 1982 and a 30 percent depletion in 1983. (Figure 5 shows changes in the ozone hole over 21 years). Molina admits, “We really sort of stumbled onto a problem of global proportions” (Wilson, 2012).

The Montreal Protocol: A global response to environmental crisis

The international community responded by enacting the Montreal Protocol on Substances That Deplete the Ozone Layer in 1989. This agreement called for a step-by-step phase-out of human-produced chemicals that harm the ozone layer. After several amendments over the years, in 2010 the Montreal Protocol became the first international treaty to be signed by all 196 United Nations members. Former UN Secretary General Kofi Annan described the Montreal Protocol as “Perhaps the single most successful international agreement to date” (United Nations, 2014).

Thanks in large part to Molina and Rowland’s ground-breaking work which led to international cooperation, the Montreal Protocol has succeeded in reducing ozone-depleting substances by 98 percent. This reduction helps to avert millions of cases of skin cancer and tens of millions of cases of cataracts, along with damage to crops and marine life. True to Molina and Rowland’s predictions, the ozone layer thinned out during the 1980s and early 1990s before stabilizing around the turn of the millennium. And in September 2014, more than 25 years after the Protocol was first enacted, a group of 300 scientists, including Molina, determined that the ozone layer is finally making a comeback for the first time since 1980 and is on target for recovery by the middle of this century (UNEP, 2014).

Science without borders

Molina and Rowland’s pioneering work earned them the 1995 Nobel Prize in Chemistry, which they shared with another atmospheric chemist, Paul J. Crutzen. Molina feels a responsibility to use his position as a Nobel Prize winner to make sure that scientific findings have an impact on society and affect public policy. “People listen to you more,” he says, “but you have to use that very wisely” (Nobel Prize Organization, 2011).

Living and working in the United States has allowed Molina to have the greatest impact on society, so he became a naturalized US citizen. This permitted him to work in US national labs, have more access to resources, and have greater influence on international policy (UNAM, 1995). Indeed, he currently serves on the US President’s Council of Advisors on Science and Technology and in 2013 was awarded the Presidential Medal of Freedom by Barack Obama (Figure 6). Molina’s work, however, addresses problems that have no borders. Seeing the urgency of increasing scientific knowledge in developing countries, he donated most of his Nobel Prize money to scientists and science educators working in these parts of the world. “Science is a great means of unification for the peoples of the world,” he said in a 1995 interview (UNAM).

But Molina hasn’t forgotten his Mexican roots and hopes that his prize spurs scientific research in Mexico. In 2005, he established the Mario Molina Center for Strategic Studies in Energy and the Environment in Mexico City to tackle complex environmental issues. As climate policy advisor to Mexican president Enrique Peña Nieto, Molina was instrumental in pushing through an “ambitious” climate change law in 2012. He celebrates the improvement in air quality in his native Mexico City, which was formerly known as the most polluted city in the world (Nobel Prize Organization, 2011).

Molina also has a keen interest in encouraging minority students to pursue careers in science. In his youth, there was a lack of famous Latino scientists to look up to because, as he relates in an interview with students to celebrate Hispanic Heritage, “there wasn't as much a tradition to be a scientist in our culture” (Scholastic, 1998). Even in his adulthood, he has continued to believe that “We have too few scientists coming from, for example, Hispanic backgrounds, and it's clearly something that needs to be improved” (Thomson, 1995). He promotes this goal through involvement in the Society for the Advancement of Chicano and Native American Scientists and the American Chemical Society (ACS) Scholar Program, which encourages underrepresented groups to become scientists (UCSD, n.d.).

Averting catastrophe one issue at a time

Over the past several decades, Molina has turned his attention to climate change. He draws parallels between climate change and the depletion of the ozone layer: Both are global issues, both are largely the result of human activities, and both need to be addressed at a policy level. He sees both issues as undeniable proof of what human activities are doing to the Earth on a global scale, but acknowledges that the issues he is tackling now will be trickier to solve than the problem with the ozone layer. The science of climate change is more complex and controversial, and unfortunately, climate change can be as much a matter of politics as of science.

When it comes to climate change, the fundamental science is well established. In fact, 97 percent of the world’s climate scientists agree that the climate is changing and humans are the cause. However, some government officials politicize the issue and dismiss the science behind it. One of Molina’s chief missions is to try to communicate with the skeptics.

The basics of the climate system are well understood, but the details – for example, predictions about exactly how many degrees the temperature may change – are more complicated. Molina likens our scientific understanding of climate change to a jigsaw puzzle: “Many pieces are missing, and some might even be in the wrong place, but there is little doubt that the image is clear, namely, that climate change is a serious threat that needs to be urgently addressed” (US Senate Select Committee Hearing, 2010).

Molina stresses that it doesn’t make sense to require certainty before we take action. It should be enough to know that there is an unacceptably big risk to Earth if we do not control human actions that contribute to climate change. It is not wise to continue with “business as usual,” especially when it comes to the environment, since it is often necessary to act on a threat that is not seen. He offers an example: “When you drive your car, you wear seat belts and have air bags – and not because you have a certainty that you will crash.… It doesn’t make any sense to require certainty” (Nobel interview, 2014).

To bridge the gap between science and government, Molina has embarked on a globetrotting mission to communicate the science of climate change in an understandable way and to convey the importance of the problem, along with consequences and possible solutions. He says that one of the biggest challenges is to cut through misinformation and misconceptions.

“Our planet is small and there are too many people to continue living the way we are,” Molina cautions. If humans do not change their reliance on fossil fuels, we face bigger risks, such as abrupt climate change, which can have disastrous results (Nobel Prize Organization, 2014). UN Secretary-General Ban Ki Moon echoed the sentiment during the People’s Climate March, when he told reporters, "There is no Plan B because we do not have Planet B” (Westbrook, 2014).

Molina, ever the optimist, is certain that we can deal with the problem by working together. He says that we have the power to do something about global climate change; it’s not too late or too expensive. All sectors – scientists, economists, politicians, the public – must come together to work toward a plan, and with urgency since it will cost much less to deal with the problem now than being forced to deal with the impacts of a problem left unaddressed for too long (Yale Environment 360, 2014). He says, “Scientists may depict the problems that will affect the environment based on available evidence, but their solution is not the responsibility of scientists but of society as a whole” (Centro Mario Molina, n.d.).