When Wangari Maathai was awarded the Nobel Peace Prize in 2004, it was a vindication of her life-long argument that social and economic security cannot be achieved without environmental protection. “Wars are fought over resources,” she said. “If we did a better job of managing our resources sustainably, conflicts over them would be reduced. Protecting the global environment is directly related to securing peace.”

Maathai, who died of ovarian cancer on 25 September 2011, began her career as a biologist, studying in the United States and Germany before returning to Kenya for her doctorate. By 1977, she was a professor of veterinary anatomy at Nairobi University and the mother of three children. Despite impressive academic achievements, then unprecedented for a black African woman, it was her increasing involvement in poverty alleviation, and political and environmental activism that was to define her life — her cause revolved around exposing the link between poverty, power, governance and environmental stewardship. “The more you degrade the environment, the more you dig deeper into poverty,” she said. “But, poor people will cut the last tree to cook the last meal, because they are concerned about survival, not about the rules of climate change.” That same year, she set up the Green Belt Movement, a project that paid rural women small amounts to plant native tree seedlings.

Credit: MIA MACDONALD / GREEN BELT MOVEMENT

With the backing of international agencies, such as the United Nations Environment Programme (UNEP), the project planted an estimated 45 million trees in Kenya alone, benefiting 900,000 women, and was rolled out across the continent and beyond. The Billion Tree Campaign to plant a billion trees per year, was initiated by UNEP in 2006 under Maathai's patronage, and has so far planted almost 12 billion trees. On average, each tree removes an estimated 22 kilograms of carbon dioxide from the atmosphere per year. Tropical forests can sequester around 38 tonnes of carbon dioxide per hectare per year, in addition to providing other ecosystem services, including water conservation, timber and improved soil quality.

Maathai took on the poor world's struggle with development and its environmental impacts long before it became fashionable, and she did so despite overwhelming opposition from business interests, continual political harassment, imprisonment and many other hardships. The difference she made to the lives and landscapes of rural Africans could not have been achieved without the support and intervention of influential people and agencies in the rich world, and this continued persistent vigilance and assistance will need to continue if we are to enable other visionaries to carry on Maathai's work.

“We have a responsibility to protect the rights of generations, of all species, that cannot speak for themselves today,” she said. “The global challenge of climate change requires that we ask no less of our leaders, or ourselves.”