The growing movement to divest from the fossil fuels causing climate change and invest instead in clean, sustainable energy reached an historic milestone today: $50 billion.

Over 800 global investors have now committed to divest their holdings in fossil fuels. New signatories encompass a broad diversity of sectors and regions—including foundations, individuals, faith groups, health care organizations, cities and universities around the world. Their pledge was revealed at a news conference in New York today, and will be presented tomorrow at the United Nations Climate Summit where over 120 world leaders will gather.

A leading advocate of the movement, Archbishop Desmond Tutu, called on institutions and people of conscience to divest in a video recorded for the announcement: "Climate change is the human rights challenge of our time. We can no longer continue feeding our addiction to fossil fuels as if there is no tomorrow, for there will be no tomorrow." He called for a freeze on all new fossil fuel exploration as the companies cannot safely burn 75% of known reserves.

The fossil free Divest-Invest movement has grown explosively since its launch three years ago. Today's announcement includes over 650 individuals and 180 institutions, including 50 new foundations added to the 17 who pledged in January. Together these institutions hold over $50 billion in total assets. Signers pledge to divest from fossil fuels over five years, taking a variety of approaches.

The foundations announced today include the Rockefeller Brothers Fund, whose original endowment comes from wealth generated in the Standard Oil Company. The Fund will be divested first from coal and tar sands by the end of this year, with more to come thereafter.

"John D. Rockefeller, the founder of Standard Oil, moved America out of whale oil and into petroleum," explained Stephen Heintz, President of the Rockefeller Brothers Fund. "We are quite convinced that if he were alive today, as an astute businessman looking out to the future, he would be moving out of fossil fuels and investing in clean, renewable energy."

New Divest-Invest signatories are regionally diverse, with many hailing from the climate frontlines in Australia and Africa. "African people are already experiencing global warming, including heat waves, drought and related food shortages," said Akwasi Aidoo, Executive Director of TrustAfrica. "We cannot continue to rely on fossil fuels if we are to chart a solid path to sustainable development and shared prosperity."

Beyond new philanthropic commitments, upwards of 650 individuals are joining under the banner of the newly formed Divest-Invest Individual. These include former Wall Street executives, businesspeople, celebrities, thought leaders and everyday Americans. In announcing the individual commitments, actor Mark Ruffalo called pushing to move out of fossil fuels "the fight of our lives."

"The economy is already decarbonizing," Generation Investment Management co-founder and senior partner, David Blood, explained at the news conference. "Investors must recognize that shifting away from fossil fuel dependency is no longer just about risk but also about opportunity."

Major NGOs, faith groups, and health organizations are also pledging their support, including most of the big environmental groups. The commitment of the World Council of Churches -- a fellowship of over 300 churches that represent some 590 million people in 150 countries -- increases the reach of the movement. They join other denominations and faith institutions, including The United Church of Christ and Union Theological Seminary.

"We encourage heads of state meeting at the United Nations to join with all people to take decisive steps to reverse climate change. Let us move together to rebuild, restore and reclaim a life-giving and life-empowering world where all live in dignity, peace and justice," said Dr. Agnes Abuom, Moderator of the World Council of Church's Central Committee.

An unprecedented convergence of reports made clear this year that climate tipping points of no return are approaching. From the Intergovernmental Panel on Climate Change's Fifth Assessment to the National Climate Assessment, "the message is clear. We need to end the fossil fuel era. It's doable and profitable, and the costs of inaction are unthinkable," said Wallace Global Fund Executive Director Ellen Dorsey, a founder of the divest/invest campaign.