buy, buy, buySadly, the human world's economy depends on people buying more and more. This is called 'economic growth' and is supposed to be good. In a sense it is because when economies grow, more people have jobs. Not having a job is a very miserable thing for most humans because no job means no money. No money means... well, you can work that out.

But economies don't always grow. Sometimes they go bust and collapse. This happened famously in 1929 when all the world's big economies — especially the USA — crashed and millions of people lost their jobs. It has happened several times since, most recently in 2008.

So how do you arrange for people to have jobs without destroying the planet? This is a very difficult question and nobody knows the answer. The best hope seems to be to encourage people to buy — to consume — things can be be recycled, which don't harm the environment and which don't need to be transported long distances. Buying stuff you want — food, clothes, whatever it might be — need not be damaging if what you buy is made in some way which can be done over and over again. 'Sustainable' is the word.

The best example is food. Growing food depends on soil, air, water and sunlight. There's plenty of all of those in most places. So people can carry on growing lots of food for ever if they use sustainable farming methods (which they mostly aren't!). Fishing should be sustainable too. Because people are greedy and have caught so many fish, there are hardly any left in many seas. No adult fish means no baby fish and no new fish. So fishing areas, like economies, collapse.