Actor Leonardo DiCaprio has applauded United Nations leaders for signing a historic climate change agreement on Friday (22Apr16).

The 41-year-old Oscar-winning The Revenant star, who is a United Nations Messenger of Peace, spoke at a landmark gathering held in New York City on Earth Day, and saluted the representatives from 175 countries, who came to the meeting to sign the Paris Agreement on climate change into international law.

Leo admitted his recent research into the issue left him "absolutely terrified" about what will happen to the planet if greenhouse gas emissions are not addressed.

“Our planet cannot be saved unless we leave fossil fuels in the ground where they belong," he stressed, according to Entertainment Weekly. “After 21 years of debates and conferences, it is time to declare: no more talk, no more excuses, no more 10-year studies, no more allowing the fossil fuel companies to manipulate and dictate the science and policies that affect our future."

The longtime environmental advocate also suggested the issue of climate change was similar to that of American slavery, citing historical U.S. leader President Abraham Lincoln, who served during the abolition of slavery and the Civil War.

The actor noted that addressing climate change is an equally important political issue that will affect many future generations.

“(Lincoln) was speaking before the U.S. Congress to confront the defining issue of his time: slavery,” he said. “Remarkably, his words ring as true today when applied to the defining crisis of our time: climate change.”

The Paris Agreement is a non-binding treaty existing within the framework of the United Nations Framework Convention on Climate Change (UNFCCC). The document was created in an attempt to slow down the effects of greenhouse gases, such as carbon dioxide, on the earth's temperature, which is rising rapidly.

The accord contains stipulations aimed at limiting global warming to "well below" two degrees Celsius by the year 2100.

The Paris Agreement must now be processed in each country in accordance with the nation's own governmental laws - a process that could take many months.