As world leaders, UN officials and thousands of hangers-on gather in Rome to talk about food, the US Department of Agriculture has released a fascinating map showing how food price increases affect trade balances.
On the face of it, this looks like bad news for developing countries, especially in Africa. A few traditional food exporters, mostly temperate-zone countries like the USA and Argentina, stand to improve their trade position, while densely populated Asia and Africa will see their trade balances move towards deficit.
However, we should beware the mercantilist fallacy that a trade surplus is somehow a sign of virtue: in fact, it could be a sign of excess saving (Japan, after all, ran a trade surplus throughout the recession years of the 1990s). So maybe a slide towards deficit in countries like Nigeria or Peru, where high commodity prices have created trade surpluses and risks of 'Dutch disease', isn't such a bad thing.
The problem with this graph is that it doesn't tell us anything about the terms of trade between countries. Trade in food, like anything else, is determined by relative prices: so the real question is which countries stand to improve their terms of trade as a result of food price changes. After all, if your terms of trade improve, you can afford more imports for the same quantity of exports. You could conceivably increase your import volume while the value of your imports falls. That's a real welfare gain. A trade surplus is nothing of the sort.