MOST OF THE WORLD, reviewing the economic progress of the past decade, grumbles that growth and prosperity were less than everyone had expected. But there is one region in which the 1970s imposed a far more dire trend than a mere slowing of upward progress. In a broad band across Africa, tens of millions of people are living in poverty more severe than when the 1970s began.

The World Bank has published its annual statistical atlas, an outstanding accounting of humanity's struggle against its ancient enemies, famine and privation. In the industrial -- and industrailizing -- countries, the deceleration of economic growth had a lot to do with the sharp increases in the cost of oil. In central Africa, older and more familiar causes were at work: war and natural disaster. The steady encroachment of the desert has created a band of devastation from the Atlantic eastward, and sent floods of refugees into the next tier of countries not yet physically touched by the changing climate. To the east and south, a decade of wars and revolutions has left poor countries more desperately poor than ever. That's the zone from Ethiopia and Uganda down to Zimbabwe, and from Angola across to Mozambique.

Of 125 countries throughout the world above mini-state rank, only 17 were poorer per capita in 1978 than in 1970, the World Bank finds. One of those 17 was Jamaica, which came close to committing economic suicide in a series of ill-advised political experiments. One was Bhutan, in the Himalayas. All of the remaining 15 are in sub-Saharan Africa. The bank's preliminary figures for 1979 suggest a measure of recent improvement in some of these countries, but hardly any reversal of the general pattern.

In their tidy and detached way, these columns of numbers reflect an enormous accumulation of misery. There is no possibility that the countries along the desert's rim can begin to feed themselves without help from a distant and more fortunate world. One of the responsibilities of rich countries' wealth is to support the economic development that can interrupt this spiral downward. One of the responsibilities of stable and peaceful countries' diplomacy is to keep pressing for peace in Africa so that development can proceed.