Actor Leonardo DiCaprio, in his capacity as United Nations Messenger of Peace, addressed world leaders gathered at the UN on 22 April to sign a deal to slow climate change. The deal, widely known as the Paris Agreement, is set to be signed by more than 165 countries – the most states to endorse an international agreement, which its backers hope will inspire swift implementation.

But DiCaprio cautioned that signing the agreement is not enough and that real life implementations are needed to reverse climate change.

Our planet cannot be saved unless we leave fossil fuels in the ground where they belong. And upheaval, a massive change is required right now, one that leads to new collective consciousness, a new collective evolution of the human race, inspired and enabled by a sense of urgency from all of you, he told delegates gathered at the UN General Assembly hall.

He continued: We can congratulate each other today, but it will absolutely nothing if you return to your countries and fail to push beyond the promises of this historic agreement. Now is the time for bold, unprecedented action. My friends, look at the delegates around you, it is time to ask each other: Which side of history will you be on?

The UN expects some 60 heads of state and government at the signing ceremony. The previous first-day record for signatures was set in 1982 when 119 states signed the Convention on the Law of the Sea.

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 signs and policies that affect our future. This is the body that can do what is needed. All of you sitting in this very hall. The world is now watching. You will either be lauded by future generations or vilified by them, DiCaprio said.

Many states still need a parliamentary vote to formally approve the agreement. It will only enter into force when ratified by at least 55 nations representing 55% of man-made greenhouse gas emissions. China and the US, the worlds top emitters which together account for 38% of emissions, are due to sign, along with Russia and India, who round out the top four.