Prince Charles, the heir to the British throne, addressed the opening session of the United Nations conference on climate change near Paris on Monday, calling for an end to procrastination in addressing the world’s environmental crisis.

After expressing his condolences for those who died in a series of terrorist attacks in the French capital this month, he identified climate change as the greatest threat to humanity.

Echoing the words of Christiana Figueres, executive secretary of the United Nations Framework Convention on Climate Change, Prince Charles said, “Rarely in human history have so many people around the world placed their trust in so few.”

He encouraged world leaders and delegates at the summit meeting to consider the needs of younger generations, saying, “I can only urge you to think of your grandchildren, as I think of mine, and of those billions of people without a voice.”

Saying that the world has “the knowledge, the tools and the money” to make a difference, Charles said it was essential that global warming be restricted to 2 degrees Celsius (3.6 Fahrenheit).

At a similar climate conference in Copenhagen six years ago, Prince Charles had warned that within 100 months, or a bit more than eight years, the world would reach a point of no return on climate change. He referred to those remarks in his speech on Monday: “Have we really reached such a collective inertia that ignores so clear a warning? Eighty of those 100 months have now passed, so we must act now.”

Addressing the leaders and delegates at the conference, he said, “You are all here to set us on the road to a saner future.”