"Tens of millions of human deaths, mass extinction, hundreds of trillions in costs."
The words above, splashed across a massive screen in big red letters in a Princeton classroom this spring, forecast the consequences by 2050 of people continuing to burn fossil fuels and degrade the environment.
"These are eye-popping numbers, world-war levels of trouble," said Stephen Pacala, the Frederick D. Petrie Professor in Ecology and Evolutionary Biology, as he delivered the last lecture of the semester for Princeton's new undergraduate environmental studies course "The Environmental Nexus."
"We can estimate the cost of business-as-usual through this century and through your lifetime — and the costs are considerable," Pacala told students packed into a McDonnell Hall lecture room on May 5 as he walked beneath the towering screen. "It's really critical to take home from this course that the accelerating damages are already among us."
The scientific knowledge and technology to mitigate these bleak effects already exist, Pacala said. The challenge will be overcoming the many other hurdles to confronting climate change — and the undergraduates who sat listening to Pacala will be the ones who have to figure out how. Before time runs out.
"The real impediments are economic, political, ethical and imaginative. We're going to have to solve those problems to solve this problem," Pacala said. "This is during your watch — we do this, or we don't."
The premise of the "Environmental Nexus," which debuted this semester, is that the undergraduates of today will be left to deal with the future effects of the global environmental crisis, particularly climate change, the loss of biodiversity, and food and water shortages. These calamities are expected to peak around 2050 when the first-year students of 2017 are around 50 years old.
Because every facet of their lives will be touched by the environmental crisis, the unique structure of "Environmental Nexus" approaches the topic from distinct perspectives represented by the four Princeton faculty who co-teach the course. Pacala, who developed the class, leads the scientific portions of the class.
Marc Fleurbaey, the Robert E. Kuenne Professor in Economics and Humanistic Studies and professor of public affairs and the University Center for Human Values, addresses the political and economic considerations — and challenges — students will contend with.
Rob Nixon, the Thomas A. and Currie C. Barron Family Professor in Humanities and the Environment and professor of English and the Princeton Environmental Institute, examines how the arts humanize the environmental crisis to inspire empathy and action.
"It's a course for which I don't know a parallel anywhere else," Pacala said.
The course centers on thrice-weekly lectures and discussions that often feature speakers who represent diverse areas of the climate problem such as engineering, communication and architecture. On April 7, Todd Stern, the U.S. Special Envoy for Climate Change under President Barack Obama and the country's chief negotiator at the 2015 Paris Climate Agreement, spoke on the political difficulties of curtailing climate change.
Paula Kahumbu, CEO of the Kenya-based conservation group Wildlife Direct who received her Ph.D. in ecology and evolutionary biology from Princeton in 2002, led a multi-part discussion on Kenya with Nixon and Dan Rubenstein, the Class of 1877 Professor of Zoology and professor of ecology and evolutionary biology. The series was intended to provide students with a sense of climate action and climate change as it exists outside the United States — where the effects are often already felt, Kahumbu said.
"The huge impact of Western consumerism on other parts of the world, including Kenya, means that global poverty is going to get a lot worse," she said. "We have people today who can't have meals because of climate change."
Students in the "Environmental Nexus" choose from one of six precepts that delve into a specific topic, such as ethics, mathematical modeling, laboratory sciences or arts and literature. The photos below capture a session in the science with a laboratory precept.
"Where are ethics in this debate? I think we've seen in this course that ethics are everywhere," Lane said to students at the last lecture.
In the ethics precept led by Lane, students such as Dyonishia Nieves, a senior in ecology and evolutionary biology, consider their personal responsibility to help solve the problems posed by the "Environmental Nexus." "We are more privileged than most, and we have so many amazing opportunities to incite change with our actions and words," Nieves said. "However, with this privilege and opportunity comes responsibility."
Added Nieves: "If there is anything that I have learned from the 'Environmental Nexus' course and throughout my time at Princeton as a whole, it is that to solve global environmental issues is to tackle issues of global inequity.
"As members of a high-emitting, developed nation, we are obligated to do all that we can to mitigate the environmental and social effects of climate change," she said. "Don’t take more than you need or want. Start with small actions and build your way up. Above all, as students, we must set an example of sustainability for our peers and communities."
Lane challenged students to initiate a reframing of societal environmental values through social and political engagement. "You, each of us, is part of shaping those domestic perceptions of interest; we can reshape the norms that we find acceptable at a local, regional and global level," she said.
"The real challenge then is how are you going to define your own self-interest as you consider the nexus problem going forward," she said. "Self-interest is not just material interest — self-interest can also include your perspective on the harms to others — the harms to other species, to other people, to other future people — that can become part of our self-interest as we choose to understand and define it."
"If we think of all the great social struggles over the course of time, all of those have been fought out on the territory of the imagination," Nixon said during the last course lecture. "As the novelist Ruth Ozeki reminds us, 'The very act of storytelling is itself a form of hope.'"
Similar to slavery, apartheid and the destigmatizing of AIDS, for many people the effects of environmental degradation are too vast, too distant in time and space, and too inequitably distributed to have personal resonance. Arts and literature humanized these struggles to inspire action, and the same is happening for the environment, he said.
"In all of these cases, we have something that is both of immeasurable importance and ultimately immeasurable," Nixon said. "The data is so important, but also the translation of that data into visceral experience — what does it feel like?
"A lot of filmmaking, a lot of artwork, a lot of storytelling around climate change in particular is trying to get a foothold in the future, trying to humanize 2050 and see ourselves from that perspective," he said. "Again, to have some kind of emotional impact and to narrow that distance between ourselves and the middle of the century."
In a small room in Lewis Library one morning, students in the quantitative reasoning precept tried to estimate the worth of future generations' happiness, specifically when compared to the cost of curtailing carbon emissions now. As their last assignment of the year, the students had to construct economic models of the social cost of carbon.
"We all cared less about the welfare of future people to some amount," sophomore Elizabeth Wright said about her group's model. At the same time, "how can you enjoy things now if the climate's unpredictable, and how can businesses thrive if you don't know what will happen year to year?"
The climate and economic models the students build in the precept are how scientists and policymakers disclose the trends in scientific data, said preceptor Ian Bourg, an assistant professor of civil and environmental engineering and the Princeton Environmental Institute. "You can't necessarily know by looking at the equations what behaviors will emerge until you combine them together," he said.
Nonetheless, some factors are so intangible that students must make moral determinations. In presenting her group's model, first-year student Liana Cohen said that happiness and disease are "obviously big factors in terms of human happiness, but how can we measure them? At some point, our equations can't represent these factors enough so that we can put them in the model." Her groupmate Christian Kelling, a sophomore, added, "What our model fails to represent is human-life losses — that will impede economic growth in the future."
Matthew Ramirez, a sophomore in ecology and evolutionary biology and environmental studies, said that the precept increased his overall understanding of the environment and climate.
"One of the strongest features of this precept was its applicability to the broader course material, enhancing my understanding of the curriculum as a whole," Ramirez said. "I was reasonably familiar with the physical mechanics of climate change, but would have been at a loss if asked to independently model the various aspects of the phenomenon.
"The final problem set stood out as exceptionally insightful because it involved applying a number of economic and moral factors that we were free to alter in order to understand the various range of estimates for the social cost of carbon," he said. "I couldn't’t resist the opportunity to participate in a novel, inspired class format such as this."
"The strongest feature of this precept is that it is approachable to non-STEM concentrators and that it applies quantitative analysis to the general topics we discuss in lecture," said sophomore Daniel Shepard, who is majoring in philosophy.
"Climate modeling is very complicated, but even a simplified model like ours could still generate predictions that were reasonable," he said. "The final problem set showed me that the kinds of assumptions economists make about how much to value the future can be somewhat arbitrary, but are frighteningly important in how the social cost of carbon is calculated.
"Basically," Shepard said, "every lesson from this class has had some impact that will be important in the future."