Earth Day is a time to celebrate our planet and reflect on how our personal choices have an impact on the world around us. However, it is also a time to recognize that we need not only personal responsibility, but also social and institutional changes to address the colossal challenges facing our planet.

We know you’ve heard it before: Climate change poses an enormous threat not only to our natural ecosystems but also to the quality of life of humans around the world. Though scientists continue to tweak their sensitivity parameters and to better understand the precise impacts of a warmer world, the essence of our challenge is clear: Our society must rapidly curb our greenhouse gas emissions in order to avoid disaster.

Earth Day has a rich history of environmental activism. The first Earth Day in 1970 marked the beginning of the modern environmental movement; twenty million people in schools and communities across the country took to the streets to demand greater environmental protection. The momentum of this new movement prompted the creation of the Environmental Protection Agency, the expansion of the Clean Air Act and the passage of the Endangered Species Act and the Clean Water Act.

Today’s environmental challenges are more complex and more terrifying than those of the 1970s. The scale of the threat posed by climate change would have been unimaginable to those early environmentalists 43 years ago. But thankfully, the environmental movement is again gaining steam. And again, across the country and the planet, university students are leading the way. We are taking action to protect our future.

We are making personal changes to reduce our carbon footprints so as to live our lives in accordance with our own values, but we recognize that this alone will not be enough. We are demonstrating support for political action on climate change. And now, specifically, we are looking at the moral implications of Stanford’s investments in the fossil fuel industry.

We can afford to burn only one fifth of fossil fuel companies’ existing reserves if we wish to avoid internationally agreed upon two-degree warming benchmark of catastrophic climate change. However, the value of these companies is dependent upon their entire reserves. Their net worth is based on a massive “carbon bubble,” which will pop as humanity recognizes that most of these reserves are unburnable.

But aside from being poor investment strategy, investing in fossil fuels is simply wrong. Given all we know about climate change, and given our school’s founding commitment to “promote the public welfare by exercising an influence on behalf of humanity and civilization,” we must divest from companies whose business model is based on extreme climate change and whose massive lobbying budget has strangled all attempts at real government action.

Students at Stanford and more than 300 other colleges and universities are calling on our schools to divest our endowments from fossil fuel companies. The climate crisis cannot be solved by divestment alone, nor can it be solved if we continue to support business-as-usual environmental destruction. Divestiture will help to remove the social license of companies to exploit our planet and will open the door for meaningful dialogue and policy progress.

We are living at a pivotal time in Earth’s history, one that our kids will look back on in their history books. Climate change will be a defining issue of our generation. As the window for meaningful action gets smaller and smaller, we must decide to be on the right side of history. It’s time for Stanford to divest from fossil fuels. It’s time for us, as students, to keep our school’s actions in line with its mission. It’s time to fight for a stable climate – for our own future, for our children, and for the lives of millions of people around the world.

Sign our petition at act.gofossilfree.org/act/Stanford-University. For this Earth Day, join the movement.

Sophie Harrison and Graham Provost, Fossil Free Stanford