Some women grow into being forces of nature, and others are born that way. Wangari Maathai, the Kenyan-born globalist with a vision for environmentalism that far exceeded the imagination of those she was surrounded by, was one of the latter.

Born in 1940 in Kenya’s central highlands, Maathai grew up surrounded by thick forests and clean rivers. When she returned home in the 1970s — after becoming the first woman in East and Central Africa to earn a PhD, which she did in the country’s capital, Nairobi — much of the landscape she knew was gone. It has been cleared for profit, its soil eroded away. So, in 1977, she began the Green Belt Movement, which aimed to mobilise women in rural villages to plant trees, restore land, and thereby reclaim their own economic and political power.

It was quiet work, uncontroversial even — but in a one-party state with little tolerance for dissent its impact rippled. To empower people and particularly women with knowledge and agency over their environment meant that the government had to be accountable on questions on land rights, clean water, and corruption. Maathai was arrested, beaten, vilified by the government of Daniel arap Moi. But she kept going. She continued to fight to save public parks from development, campaigned for political prisoners, and insisted that environmental destruction and human oppression were two sides of the very same problem.

In 2004, she was named the winner of the Nobel Peace Prize, the first African woman to do so, for proving that protecting the planet could also shore up democracy and contribute to human progress. When she died in 2011, she left behind millions of trees, a movement that had spread far beyond Kenya, and a simple but radical idea: that the fight for the earth, and for its trees, is linked undeniably to the fight for human freedom.