Vancouver-born environmental organization Greenpeace is coming home on Thursday to celebrate its big 4-0.

Mayor Gregor Robertson will be proclaiming "Greenpeace Day" in the city at the Vancouver Maritime Museum to honour the origins of the organization.

The international executive director of Greenpeace, Kumi Naidoo, will be at the event to accept the honour along with Greenpeace acting B.C. Director Jessica Wilson and the executive director of Greenpeace Canada, Bruce Cox.

The event is a way to pause and reflect on the history of Greenpeace and celebrate its success around the world and specifically, in Vancouver, where it all began, said Wilson.

"It's not often with this movement – which is moving at breakneck speed – that we pause and reflect on where we come from, how far we have come and celebrate our successes," said Wilson. "Greenpeace could not have been born anywhere else – there is a deep connection people in Vancouver have with their natural environment."

Chief Janice George of the Squamish Nation will open the ceremonies, which will include the planting of a yellow cedar by the living founding members of the organization and their family members, said Wilson.

There will also be a performance by 10-year-old Greenpeace member Ta'Kaiya Blaney. The young activist will sing a song about the repercussions of oil spills she has written herself called "Shallow Waters."

Greenpeace was founded in Vancouver on Sept. 15, 1971. Its first campaign was launched under the original name Don't Make a Wave Committee.

According to the Greenpeace website, the organization got its start when a crew of 12 sailed to Amchitka, Alaska to protest U.S. underground nuclear testing. Although the bombs were detonated, the protest garnered international attention and shortly after the island was declared a bird sanctuary. In 1972, the name was changed to Greenpeace.

In the 40 years it's been active, Greenpeace has grown to become the world's largest independent environmental organization, with nearly three million supporters in 41 countries. The organization, which is entirely member-funded, employs 1,600 staff across the globe.