What started as a meme is now an international movement toward reforestation.

When the YouTube star Jimmy Donaldson ⁠- aka MrBeast ⁠- hit 20 million subscribers on YouTube in May, a fan suggested there was something he could do to commemorate the milestone and "single handedly save Earth" at the same time.

"Petition for MrBeast to plant 20 million trees for 20 million subscribers special," a Lisa Simpson presentation meme posted to Reddit read.

Donaldson took notice, then connected with fellow YouTuber and former NASA engineer Mark Rober to come up with a plan to complete the challenge, Reed Duchscher, Donaldson's manager and the president of the talent-management firm Night Media, said.

"They wouldn't let it go," Donaldson said in a statement. "All my video comments were about trees!"

Rober thought to enlist the help of the nonprofit conservation organisation Arbor Day Foundation, and five months later, the partnership known as #TeamTrees has grown to include "basically every digital creator you can think of," according to Duchscher.

The Arbor Day Foundation will use its international partnership network to plant 20 million trees in a year

Each dollar donated – over US$8 million since its official launch on Friday, including a US$1 million contribution from Elon Musk – funds the planting of one tree around the world, a process facilitated by the Arbor Day Foundation as part of its reforestation program.

"It's right up our alley," Arbor Day Foundation Vice President Woody Nelson told Business Insider. "We work with partners around the globe and try to align those funds with projects that really need help."

Local partner organisations, as well as those from as far as South America, Europe, and Australia, submit proposals to the foundation outlining their plans for planting. The foundation selects the ones with the greatest need to receive donations, Nelson said.

Fundraising will continue through December, then the first of the trees will be planted in January, starting in warmer climates like Florida and Texas, Nelson said, and eventually reach every continent except Antarctica. Not all the trees will survive, but the Arbor Day Foundation predicts only a 3 percent mortality rate.

The foundation usually racks up big donations from other large organisations, but Nelson said working with the YouTube community means #TeamTrees is generating small contributions from a massive audience.

"This is by far the fastest climb to $US8 million in individual, single donations that the Arbor Day Foundation has ever seen," Nelson said.

"Just to have it be so viral and to get so many small donations from individuals … it's just making so many people feel really good."

'This is like the Avengers of YouTube': Hundreds of influencers have joined the movement

Nelson credited the success of the campaign to YouTubers, starting with Donaldson, who personally messaged content creators he knew – many from his YouTuber Battle Royale, Duchscher said – to explain the initiative and get them on board.

Influencers like NinjaMarshmelloJeffree Star, and Joey Graceffa have already announced their involvement with the project, and Duchscher said hundreds more will soon follow in order to keep the conversation going.

"This is like the Avengers of YouTube, if the Avengers planted trees," Rober said in a statement.

While the movement started out as a "completely random" Reddit post, Duchscher said, #TeamTrees hopes it will continue to spark larger conversations about global issues like climate change.

"We know that planting 20 million trees isn't going to save the environment, but it's a step in the right direction," Duchscher said.

This article was originally published by Business Insider.

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