In a small town in Italy or Japan, the primary school closes for lack of pupils, while in a district of Dakar it turns children away for lack of places. The world is ageing on one side and growing younger on the other, and the two movements will together weigh on employment, pensions and peace in the decades ahead. Macky Sall places this question in the first rank of his candidacy for the office of UN Secretary-General.

A world that is ageing. According to the United Nations, the number of people aged 65 and over will double by 2050 to exceed 1.6 billion. Across much of Europe and East Asia, births no longer replace the generations, and the working population shrinks year after year.

Africa, the youngest continent. The median age in Africa is close to twenty, against more than forty in Europe. Each year, millions of young people there enter the labour market. That demographic dividend enriches a nation provided school and jobs follow, and their absence turns it into a source of instability.

Two needs that answer each other. Ageing societies lack workers and contributors, while young societies lack jobs and capital. Left to chance, that difference feeds tensions on both sides. Cooperation that organises training and investment, with managed mobility, turns it into a shared strength.

Demography in the negotiations. The Secretary-General can give demography the place it does not yet hold in negotiations on employment and mobility. He can also bring ageing and younger countries together around shared training programmes. Population policies will remain the business of each state. The instrument already exists: the World Population Prospects published by the United Nations give every government the state of its own age pyramid.

A head of state's experience for both pyramids. To bring young and ageing countries together, President Macky Sall draws on twelve years as head of state and on the chairmanship of the African Union in 2022. The same experience set the form of the vision statement filed with the United Nations, whose proposals (development conceived together with peace and security, a renewed multilateralism, a better-governed Organization) are written as obligations.

Africa at its heart, the world in its sights.

The United Nations' World Population Prospects are public. Read all public positions at www.mackysall.net