The first photograph of the earth from space came as part of the Apollo project in November 1967. One of the Apollo astronauts, James B. Irwin ... said of his view of the earth, “It was so far away... a little ball in the blackness of space. That does something to your soul... We saw how fragile our planet is...”... That image of the earth from space had a profound psychological effect, and we all saw it. Maybe that image was at least part of the reason why people became so worried in the 1970’s about population running ahead of resources.

The Club of Rome’s monumental book The Limits to Growth came out in 1972, with a picture of the earth on its cover. The book, written by a team of scientists, predicted disastrous shortages and mass starvation due to population pressure. Despite scientific critics of the Club of Rome’s methods, the public was ready to believe the dire forecast.

The great population scare led to various birth-control efforts around the world, notably to the “one-child policy” instituted in China in 1979. Partly due to such efforts, as well as to a change in family values, the rate of growth of the world’s population, began a long decline, to 1.1 per cent in 2005. That gradual decline led to gradual loss of concern about limits to growth. Commodity prices fell, too.

Today, we remain mostly unconcerned about global population growth. But, in the last ten years or so, we have become concerned about something else: rapid world economic growth. While it may seem that no image in the last decade was so dramatic as the first photo of the earth from space, think again.

Try searching YouTube, for example, on Greenland ice. More generally... The ability to communicate via email to everyone in the world creates a sense of the world’s smallness relative to the abundance of people in it.

We have seen photographs of hurricane and typhoon activity due to global warming, affecting people in Louisiana or Myanmar. We have seen devastation from the 2004 Indian Ocean tsunami, interpreted as a sign of crowding at the coasts.

The North Pole turned into a lake for the first time in 2000. We see aerial photos of the Aral Sea drying up. We practically can’t buy caviar from the Caspian Sea any more. The European Space Agency announced in September 2007 that satellite photos showed that the Northwest Passage appeared clear of ice for shipping for the first time ever, and that the Northeast Passage is almost clear.

With so many vivid images of a shrinking and damaged planet, is it really any wonder that human psychology is ripe for high commodity prices?

If this is the reason for high commodity prices, wouldn't we see evidence of hoarding? When there are appears to be more people at the party than there is food, how do people respond when they realize there won't be enough to go around? You can eat as early as possible so as to be sure to get your share, and that would increase the demand for food early in the party as everyone pursues the same strategy (driving up price if it is a market). And, if it is storable, you can stuff food in your pockets (or hide it somewhere else) so you'll be sure to have some later if you want it then. This also increases demand early in the party. It's the latter effect - storage for later - that seems to be missing from data on inventories.

Update: See Free Exchange for more.