Fairfax teen Vivienne Harr has been an activist for many years. A few months ago, Vivienne Harr, of Fairfax, woke up to texts of congratulations on her phone. To her surprise, during Pope Francis’ Regina Caeli address, he applauded the youth working for the Laudato Tree movement, led by Harr.

The 16-year-old San Andreas High School student has been driving the charge for awareness and fundraising for the project’s mission to plant 7 million trees along the Great Green Wall in Africa, which will help sequester CO2, combat desertification and provide food security, jobs and a hospitable environment.

After being asked by humanitarian Don Mullan to join the cause in April, she jumped at the chance.

Activism is not new to her. After seeing a photo of two enslaved boys carrying boulders in Nepal, Harr, then 8, opened a lemonade stand to fight modern-day child slavery — which found immediate success, raising around $100,000 for the charitable organization Not for Sale in a few short months. he rang the bell at the New York Stock Exchange when Twitter went public in 2013, starred in “#standwithme,” a documentary about her work, and wrote a book, “Make a Stand,” about her experiences. She also spoke on a panel with the Dalai Lama.

Q What drew you to want to be part of this?

A I have done my share in helping children out of slavery and helping people, but I have always wanted to help the environment. It came at the perfect time, I was trying to get back into serving the world and I saw it as this beautiful sign that I need to help again.

Q What do you want people to know about the cause?

A As coronavirus came in, people started to think that it wasn’t a very good time to plant trees, but in fact, it is one of the best times. Keeping a healthy climate and wildlife by planting more trees and getting more oxygen in the atmosphere is so important right now for stopping another pandemic or other diseases that come from animals. We are so close to turning around the effects of climate change. If we stay on track, things can really get better. Q What drove you to activism?

A I have always been on the side of justice, and felt like if I don’t do it, who will? This has been where it has led me, wanting to serve people. I was born in Marin and I am so lucky to have all the things I have. So many people aren’t as fortunate as me. It’s 100% my job to give back to everyone and everything. Q After your lemonade stand went viral, what was that time like?

A I can’t even believe that happened. When I was little, I loved to do lemonade stands. It made me feel so good. I used to give the profits to the Humane Society, people I knew or people who needed money. I decided to do one for child slavery and that one really just stuck with people because I don’t think people understood that was still happening, and it led me all these places. It was so fun and felt like I had a purpose in the world. There’s no better feeling than that.

Q Looking back, what stands out?

A Meeting the people I had impacted and when I was at a young age, meeting other people my age who were inspired by my work. I couldn’t believe I was the reason that they were wanting to help the world. I thought that’s a crazy effect I had on people, seeing people, just like me, feeling like they had a chance to do things in the world, and that one person could affect the course of history.