"We have to make a stand – and now is a good time," he tells PEOPLE
Credit: Lionel Cironneau/AP

As 150 heads of state gather today in Paris for the beginning of COP 21, the world summit on climate change, Monaco’s Prince Albert II is leading the charge.

A longtime environmental advocate, the prince – whose lobbying efforts have succeeded in placing a first-time emphasis on the role of oceans on this conference’s agenda – spoke with PEOPLE exclusively, just hours before addressing today’s opening session.

“Everyone realizes the urgency is upon us,” says the royal dad, 57, who marched in the COP 21 walk on Sunday alongside wife Princess Charlene and their twins Prince Jacques, who turn 1 on December 10. “We have to make a stand – and now is a good time.”

In the wake of the recent terrorist attacks in Paris, “I know there are dangers,” he added, “but I think everyone is ready for this [summit] to set us on the right course. Climate change has moved onto everyone’s agenda. And we’re at a point now where I think we have no other choice but to move towards alternative energy sources.

“If you look at the scientific evidence it’s very apparent: If we go about business as usual it is going to cost us way more.”

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The conference, he feels, comes with fuller recognition of the science. “There’s very strong evidence that the majority of greenhouse gases are human-produced and things need to be done,” he added. “Of course, this won’t be our so-called ‘last chance,’ because there’ll be other COP meetings. But we’ve never been so close to an agreement.

“Whether it is to be a completely binding agreement, we’ll see. But we’re close to having all the major players agreeing to putting us on the right course.”

The prince’s personal preparation for the conference this year has included global fact-finding visits to South America, Pacific regions and several island nations threatened by rising ocean levels.

Leaders of the countries coming, he feels, “know they’re being watched. There’s more public awareness now, and importantly, they’re beginning to understand jobs can be created if you get the right agreement.”

“What’s a little different this year as well is that there’s greater understanding of what a green or blue economy can produce in terms of new skills, new jobs. The economic impact is slow in being recognized. The vast majority of people don’t understand that alternative energy can produce tremendous job creation and economic growth. Statistics are there to prove it. They just need to be viewed.”

With world leaders attending from around the globe, “it’s funny,” observes the prince, an experienced diplomat, “but what happens in the hallways at a conference like this is as important as what goes on in the assembly hall. The agreements and networking are invaluable.”