Serena Williams' husband Alexis Ohanian recently expressed pride about his elder daughter Olympia, who vowed to fight for the planet on a rather cute handwritten note.The 23-time Major winner Williams retired from professional tennis at the 2022 US Open after her third-round loss to Australia's Ajla Tomljanovic. Since then, the American has focused on her family, comprised of her husband Alexis Ohanian, her six-year-old daughter Olympia, and her seven-month-old daughter Adira River.On Wednesday (March 27), Serena Williams' husband Alexis Ohanian expressed pride at the six-year-old Olympia's call for action on climate change.Olympia penned a cute yet heartfelt note with the words "I promise to fight for the planet" inside a heart with thick red outlines. She also listed some of her promises for Earth Day, which is observed globally on April 22.Alexis Ohanian, for his part, was appreciative of her efforts, posting the note online. He also tagged his own organization '776 Foundation', which aims to support marginalized communities, in his caption."@olympiaohanian is ready. @776foundation applications open SOON," Alexis Ohanian wrote on his Instagram stories.Via Alexis Ohanian's Instagram story from Wednesday776 Foundation, meanwhile, is a two-year fellowship offered to adults aged between 18 and 24 that was founded by Alexis Ohanian two years ago for philanthropic purposes. Recently, the fund introduced its Climate Fellowship programme for its young aspirants.Serena Williams' husband also likes to help Olympia in her backyard science experimentsSerena Williams' husband and daughter spotted at the 2022 National Bank Open in TorontoSerena Williams' husband Alexis Ohanian and elder daughter Olympia get down to various fun activities in their family home in Florida. Last August, the American entrepreneur and Reddit co-founder documented on social media how he was helping Olympia explore backyard science.In multiple Instagram stories and a post on X (formerly Twitter), the six-year-old was seen mixing colors in a plastic cup with a dropper. She was visibly having fun, and her dad couldn't help but express happiness at being a part of her activities."The best times are often the messiest," Alexis Ohanian wrote on his X (formerly Twitter) handle."Backyard science with @olympiaohanian never goes according to plan," he wrote on his Instagram stories.Via Alexis Ohanian's Instagram stories from August 2023