Agriculture, Climate, and Technology: Why Are the Tropics Falling Behind?

The tropics, sadly, continues to be a belt of poverty. The countries of the tropics all have low or middling incomes, with a few tiny or natural-resource-rich exceptions, and few of the poorest countries are outside of the tropics. The causes of tropical poverty are surely complex, involving initial endowments (Diamond), history, especially colonization, and geographical isolation (Gallup and Sachs 1999a). Central to the tropical poverty trap, though, is the impact of climate on productivity through the channels of tropical disease ecology and agriculture. This paper investigates the last channel: the causes of lower agricultural productivity in the tropics. The disparity in agricultural productivity between the tropics and the temperate zones is even greater than the disparity in income levels (figure 1). Income per capita in nontropical countries was 3.3 times the level of income per capita in tropical countries in 1995, but agricultural output per worker in the non-tropical countries was 8.8 times the level in the tropics. One would expect that the productivity of agricultural labor in poor tropical countries would be lower whether or not tropical climate or soils had an impact on agriculture. In poor countries, all labor has low wages so that a lot of labor is used in agriculture relative to other factors of production, ensuring low labor productivity in agriculture. Is poverty (due to other causes) rather