Ten African nations have pledged, ahead of Rio+20, to include the economic value of natural resources in their national accounts. Africa has taken the lead in the quest to persuade nations to include the full economic value of their natural resources in their national accounts, with the promise last month by ten of its nations to do so. The heads of state or government of Botswana, Liberia, Mozambique and Namibia, along with ministers from Gabon, Ghana, Kenya, Rwanda, South Africa and Tanzania, signed the 'Gaborone Declaration' at the Summit for Sustainability in Africa (24-25 May), co-hosted by the government of Botswana and the nongovernmental organisation Conservation International.