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The world’s wealthiest person will launch the world’s largest fund devoted to the world’s biggest problem.

That will happen on Monday, when Bill Gates is expected to announce a multi-billion dollar initiative to back clean energy, the largest ever, according to ClimateWire. Other, unspecified business leaders and billionaires are expected to join the announcement, which comes on day one of the United Nations climate change talks in Paris.

Update: Now it’s official: The Breakthrough Energy Coalition, a global consortium designed to make “large funding commitments for basic and applied research.” No specific fund totals are mentioned. But Gates is joined by a litany of tech luminaries, including Mark Zuckerberg (who posted his own note on it), Jeff Bezos, Jack Ma and Reid Hoffman, among others.

At the summit, the world’s largest nations, including China, India and the U.S., are also expected to arrive at agreements for clean energy investment and kicking fossil fuel addictions. There is some tension: Developing countries, notably India, an increasingly important actor in talks, have asked richer countries to help foot the bill through direct spending or access to tech. Gates’s donation is reportedly set to ease this tension and jump-start talks.

It should not come as a surprise. Back in August, the Microsoft founder told us why he was investing $1 billion of his personal wealth in clean energy. Global investment in research and companies using solar, wind and other solutions aiming for “zero-carbon energy” should double or triple, Gates wrote:

My own personal investments include companies working on new batteries and other storage methods and advances in solar technology. The nuclear design I am investing in would be safer than previous designs and would go a long way toward solving the nuclear waste problem. I spend a lot of time with the CEOs and scientists at all these companies discussing how to build a business around an innovative idea and take a product to market. If government research budgets open up the pipeline of innovation, not only will I expand my investments, but I believe other investors would join me in taking these risks.

According to ClimateWire, the fund launched in Paris will exceed $1 billion.

Hal Harvey, CEO of the clean energy firm Energy Innovation, told the publication that sum could still be higher. The U.S. spends more on popcorn and “at least that much defending oil fields in the Middle East,” he said.

Reps from the Bill and Melinda Gates Foundation did not respond immediately for comment.