As global citizens, we helped defeat Apartheid. As united Americans, we exposed and toppled Big Tobacco. What do these victories have in common? The core belief that it is wrong to invest in immorality. The fact that we, as average citizens, used our collective might to rise up against seemingly insurmountable and institutionalized Wrongs. And finally, the recognition that through de-investment, or divestment, money talks both economically and socially.

Divestment, which refers to pulling out of certain investments, operates on the simple principle that it is wrong to make unethical or morally ambiguous investments. Humanity’s next challenge: divesting from the top 200 offenders of the fossil fuel industry until their practices show that they have humanity’s long-term best interests at heart. Which means these companies need to immediately stop exploring for new hydrocarbons, stop lobbying in federal and state governments to preserve their special tax breaks, and pledge to keep 80% of their current reserves underground forever.

America’s divestment from fossil fuels is becoming a real and successful option as people across the nation are banding together to pressure governing bodies and organizations to pull out of fossil fuel stock. Six universities, fifteen cities, and nine churches have already committed to fossil fuel-free investments. Unfortunately, information relating to the exact proportion that organizations or even governments invest in fossil fuels stocks is not readily available. But when we start to talk about city and academic institution portfolios that are in the millions (and billions!), even investment levels of 1% make a substantial difference.

The other main power of divestment is in its hugely symbolic public message. For fossil fuels, this means the divestment campaign will succeed in America by bringing back the discussion of climate change to national awareness. Largely abandoned by a cleverly waged battle of special-interest backed misinformation campaigns, an honest scientific dialogue of climate truths has been starkly missing in American society for the past several years. So here are the truths:

Our heavy use of fossil fuels is contributing to the changing climate and severe national and international security crises. To keep the planet below the 2°C warming that climate scientists have warned to be a prudent warming limit for human civilizations, the most carbon dioxide that we can emit over the next forty years is approximately 565 to 1000 billion tonnes. Humans are currently on pace to emit 1500 billion tonnes of carbon dioxide by 2050. If all the proven international fossil fuel reserves were to be burned, we would emit nearly 3000 billion tonnes of carbon dioxide, which is three to five times our emissions limit. This means fossil fuel investments are a highly risky business—their stock prices are overvalued by 300 to 500 percent as a result of being based upon fuel reserves that consist of “ unburnable carbon

The only way we can move away from this unsustainable political, economic, and environmental situation is by decreasing our social and financial support of the fossil fuel industry’s business-as-usual practices. To this end I have been working to divest the portfolios of my school, Harvard University, and my home city of Cambridge, MA from their undisclosed investments in fossil fuels. Valued at over $30 billion, Harvard’s endowment is a particularly juicy portfolio to tackle from both an economic and a “hefty social message” point-of-view. In the process, I have had divestment discussions with a lot of people ranging from climate scientists to business experts and policy makers. The dialogues, paraphrased below, have been illuminating; the profound lack of solid opposing arguments has only served to strengthen why I think divestment is a great and viable strategy.

“I don’t think divestment is the solution,” was the short response one climate scientist gave me. Sure—I actually happen to agree with that. Divestment is not the only solution. But neither is climate research alone. Or funding of climate or energy research alone. Each of these is one of MANY critical components that contribute to the final solution. Humans are obsessed with finding a single silver bullet. But most of the time there are many different options that, in concert, lead to the desired outcome.

“A lot of fossil fuel companies are investing in academic research related to climate change and energy. What kind of a message will we be sending these funders if we pull out of our investments in their companies?” one tenured professor asked me. It is great that these companies are funding some climate and energy studies, but no amount of climate change research will make a difference if we still continue our business-as-usual path of supporting these same companies that are the source of the problem to begin with. In other words, environmental science research without an applied purpose is pointless.

We keep thinking of corporations as human beings with human ideas of morality and immorality. But businesses have one goal: to do whatever makes them the most money. They respond to market signals, and it is up to society to provide those signals. If Harvard, for instance, pulls out of fossil fuel investments the first thought the companies will have is “how do we get Harvard’s hefty investment back?” and certainly not “Oh, my feelings are so hurt….Harvard, you can take your $30 billion endowment and shove it.” It’s pretty simple: if we make it unprofitable to invest in fossil fuels, then these companies will start to forge new energy horizons to get their profits back.

Archbishop Desmond Tutu, one of the pillars of the movement to end Apartheid in South Africa, made this very point perhaps more eloquently than I just did in a conversation with the divest fossil fuel leaders from 350.org: “The divestment movement played a key role in helping liberate South Africa. The corporations understood the logics of money even when they weren’t swayed by the dictates of morality. Climate change is a deeply moral issue too, of course…Once again, we can join together as a world and put pressure where it counts.”

“I’m not an opponent of fossil fuels, but the world needs better cheaper choices of energy or we will fry the planet,” a business school professor stated following a vehement refusal to support the Divest Harvard campaign. Time to explain economics to the business experts themselves: there are two related ways carbon-free energy can be cheaper. One is by making them cheaper through a combination of heavy government subsidies and improvements in technology through research. The other—get ready for this—is by making the alternative (read: fossil fuels) more expensive! Divestment takes on the latter approach to get to the former. How else will something like a carbon tax become acceptable to citizens?

We know divestment has a long and successful history, but let me emphasize the particular challenge associated with divestment from fossil fuels. With tobacco and Apartheid, there were clear personal choices: one could choose to not smoke or not racially segregate. Energy, however, is a basic human necessity and for the past two centuries coal, oil, and natural gas have provided for our needs. We don’t have viable alternatives to fossil fuels yet only because of the resistance we have to changing what has become the driving force of nearly every aspect of our lives. The real purpose of divestment is to provide a solid push that forces us all to confront the severity of our situation, to force us all to realize that we must move ahead right NOW, and to get us all collectively thinking and acting effectively so that we can truly move beyond fossil fuels to a carbon-free energy future.

Archana Dayalu is a PhD candidate studying Atmospheric Chemistry at Harvard University.