Leonardo DiCaprio admitted in the recent UN Climate Summit, "As an actor I pretend for a living". He believed that humankind looked at climate change the same way - "as if it were a fiction".

But it's for real and it's happening now. He discussed about undeniable climate events to point out to people and leaders of the world that climate change is not about "hysteria" - it is "fact". He called on world leaders to take action and address this concern.

"The Wolf of Wall Street" star said, "We need to put a price tag on carbon emissions, and eliminate government subsidies for coal, gas, and oil companies. We need to end the free ride that industrial polluters have been given in the name of a free-market economy. They don't deserve our tax dollars; they deserve our scrutiny. For the economy itself will die if our ecosystems collapse."

Leonardo DiCaprio, who is finally on Instagram, was not only there in the UN Climate Summit - he was also one of the more than 400,000 protesters who walked in the streets of New York City to do the two-mile People's Climate March. Other environmentalists present in the protest were Bill McKibben, Jane Goodall, and Vandana Shiva. Policymakers, UN Secretary General Ban Ki- moon and former US Vice President Al Gore were also in attendance.

US President Barack Obama, in his speech in the UN summit, said that pollution must be controlled. He specifically called on China, said to be the most populous on earth and the country with the fastest increase in carbon pollution, to join in the efforts of the U.S. to lead in the reduction of carbon emissions.

"In each of our countries, there are interests that will be resistant to action. In each country there is a suspicion that if we act and other countries don't -- that we will be at an economic disadvantage. But we have to lead."