A 14-year-old girl from Kenya has achieved global fame for her efforts to save the planet, meeting the likes of King Charles and teaming up with Grammy award-winner Meji Alabi and ex-football star David Beckham in the campaign against climate change.

Ellyanne Wanjiku Chlystun was just four years old when she was motivated to act on the issue with her inspiration coming from Kenya's most-famous tree planter and Nobel laureate, Prof Wangari Maathai.

“I was doing a project in kindergarten about people who had made a difference in the world, such as Martin Luther King, Nelson Mandela and Florence Nightingale.

"However, it was Wangari Maathai, this amazing Kenyan woman, who had planted millions of trees in her community to spread awareness about what tree planting can do, and how it can develop a country or continent, who inspired me,” Ellyanne tells the BBC.

Prof Maathai championed the view that women, especially in rural areas, could improve the environment by planting trees to provide a fuel source and to slow deforestation and desertification.

She became the first black African woman to win a Nobel Peace Prize in 2004, and was also referred to as the first "green" Nobel laureate.

Prof Maathai founded The Green Belt Movement in 1977. It planted an estimated 45 million trees in Kenya by the time she died in 2011.

Determined to follow in her footsteps, Ellyanne went home to tell her mother, Dorothy, about what she had learned.

However, her mother - who was very familiar with the story of Prof Maathai, including her role as a political activist who challenged the regime of then-President Daniel arap Moi - tried to discourage her.

Recalling the conversation, Ellyanne says: “I said I want to be just like her [Prof Maathai]. But because mum knows of her and how she got beaten and hurt and put in jail, she said: ‘No, it’s better to become a lawyer or doctor and go to Harvard'.”

However, the young child was persistent until her mother agreed that she could emulate her hero.

“I remember at the time eating either an orange or lemon and I took the seed... and put it in the soil and then it started growing and sprouting,” adds Ellyanne.

“I fell in love with what I was doing, so I planted more."

This motivated her to learn about the science behind trees.

“Dr Jane Njuguna, from the Kenya Forestry Research Institute, taught me about Species Site Matching, which is finding the right tree to plant in the right area at the right time with the right tools and the right soil," she says.

With the help of her family, Ellyanne launched a not-for-profit organisation, Children With Nature, in 2017.

“Through Children With Nature, I wanted to teach kids. Some of them don’t know how they can make a difference in the area they live in,” Ellyanne says.

She says that she had personally planted about 250,000 trees by 2020, but had built a "community" of tree-lovers - not just in Kenya but also abroad - and together they had crossed the 1.3 million mark.

"I have planted trees all over the world in countries I have visited, including Uganda, Poland, the UK, Crater Lake in the USA, Zanzibar, Morocco and Zambia," Ellyanne says, adding: "I have planted the most trees here in Kenya."

However, she has fallen behind on tree-planting in the last three years as she has became involved in other campaigns to tackle climate change.

"I usually get sponsorship and collaborate with various partnerships to fund the travel. Brands can pay for the tickets and hotel. As a child I can’t pay for my tickets yet, although I’m getting there," Ellyanne adds.

On how she juggles her time between going to school and being a globe-trotting campaigner, the 14-year-old replies: "School has been very easy for me as I have excellent grades. I'm very proud of myself and so is my mum."

She attended the climate summit in Dubai in 2023, where she met the British monarch, and gave a speech that drew a link between climate change and the water-borne disease malaria.

“As weather patterns change, malaria cases are rising. Where I live in Kenya, malaria is appearing in new places where it has never been seen before,” Ellyanne told the delegates.

She returned to the theme in a video released by UK-based charity Malaria No More.

Directed by Alabi and featuring Beckham, she is the presenter of the video, which dramatically illustrates the effects of climate change.

"An angry sun, erratic skies, cyclones, floods of a cosmic size, thirsty land, falling trees - the perfect storm to spread disease," Ellyanne says in the film.

Along with children from other parts of the world, she also features in SaveOurWildlife, a documentary film produced by Sky News and Sky Kids FYI that looks at the impact of climate change on animals.

It has been nominated for a prize in the children's category at the Wildscreen Panda Awards ceremony, billed as the Oscars of the wildlife film and TV industry, currently under way in the UK city of Bristol.

In the film, Ellyanne reports on her favourite animal - elephants - and says that drought caused by changing weather patterns now poses a greater threat to their survival than poaching.

Despite the fact that she has branched out into filming, she tells the BBC that she remains passionate about tree-planting, and intends to take it up again.

"My greatest dream is to plant trees in Africa's Green Belt," Ellyanne says, referring to the initiative to halt the advancing Sahara Desert by planting trees from Senegal in the west to Djibouti in the east.

And she wants to be a "catalyst" for the planting of one-trillion trees around the world by the time she turns 18 - a goal that she regards achievable.

"I was brought up to believe that everything is possible, especially for me as a young person.

"Look what GenZ has done in Kenya, out of resilience, they managed to get a whole finance bill cancelled and the entire cabinet fired," she adds, giving a glimpse of the political streak of her hero, Prof Maathai.

But she says has no intention of forging a political career like Prof Maathai, saying: "I want to graduate from primary school and then get into high school and then get into college. I want to specialise in economics, that’s for sure."