A longtime environmental activist, Leonardo DiCaprio has already pledged millions to fund organizations focused on protecting wildlife and preserving natural resources.

The 40-year-old Hollywood actor announced this week that he is donating $15 million – his biggest single grant to date – to support 30 different groups, including Amazon Watch, Save the Elephants and the World Wildlife Fund.

"The destruction of our planet continues at a pace we can no longer afford to ignore," DiCaprio said on his foundation's website. "I am proud to support these organizations who are working to solve humankind's greatest challenge."

DiCaprio has been a vocal advocate for environmental issues throughout his career – his Leonardo DiCaprio Foundation supports conservation projects in more than 40 countries.

Last year, the United Nations named him a UN Messenger of Peace with a special focus on climate change. Speaking at the UN in September, he said, "This disaster has grown beyond the choices that individuals make. This is now about our industries, and governments."

(WATCH DiCaprio's UN speech below from The Guardian) – Photo: UN Speech, Guardian

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