There was no better person to speak on the UN’s International Day Of Happiness than the ‘Happy’ hitmaker himself Pharrell Williams, who took to the podium in New York on Friday. The singer used his speech to address the young crowd on the subject of climate change and why we need to protect our planet and act now.

Pharrell WilliamsPharrell Williams during the International Day Of Happiness

"Protecting our planet is fundamental to the pursuit of human happiness," Pharrell told the crowd at the UN General Assembly. "We only have one home and there's climate change... If you don't (take) care of your home, you don't have a life, and we have to transition from climate change to climate action.”

"If you look at our behaviour is hard to believe we’re all aware we only have one planet," Williams continued. "My main inspiration for being here today is that we’re in trouble, but we can change that. This earth is our home.”

More: See Our Pictures Of Pharrell During The 'International Day Of Happiness' At The UN

As for what makes the singer himself happy, Pharrell told the young audience, ”Music brought me happiness… You should know happiness is your birthright.”

An hour before delivering the speech the singer had helped make the Empire State Building look a little more cheerful, flipping the switch to turn the iconic building's lights yellow as part of the International Day of Happiness celebrations.

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All week, celebrities such as Charlize Theron, Michael Douglas, James Blunt, Ed Sheeran and John Legend have been getting involved in the United Nations #HappySoundsLike campaign, sharing some of their favourite songs to create "the world's happiest playlist.”

Established in 2012 by the United Nations General Assembly, the International Day of Happiness aims to recognise the importance of happiness and well-being as "universal goals and aspirations in the lives of people around the world.”