A good cobber, Peter Adams of Windgrove, has a fascinating blog — Life on the Edge — that often challenges his readers.
Today’s entry was typical. He asks: How much of the earth’s land is available to grow food?
Imagine, says Peter, that the earth is the apple above.
Take this apple and cut it into four quarters. One part is covered by land. The others are covered by water. Discard these three pieces.
Cut this land section in half. One of these halves is covered with mountains, desert or ice. Discard this piece.
Cut the remaining piece into fourths. Three of these are rocky, too wet, too hot, too infertile, or covered with roads or cities. Discard these.
Only 1/32 of the apple remains.
The thin layer of red of this section, shown left, represents the topsoil that must feed the world.
We had better look after it.