A complex system

1 The world we live in is a very complex system of things and living beings. They interact with each other, and over time they create a balanced system which we call an ecosystem. Things and living beings in this system all depend on each other, and if there is a small change in one part, a significant change happens in another part over time – and that change can be enormous. We humans are a part of this ecosystem, and sometimes we do things that affect the whole system.

2 Have you heard of Thomas Midgley? He was an American mechanical and chemical engineer and inventor who made two very important but dangerous products. He added lead to petrol to make it burn better in car engines. This also helped car engines to last longer. These were the positive side of leaded petrol. The negative effects of this invention became clear in the 1970s. The fumes from cars contained lead, and this caused serious health and psychological problems. It made people around the world ill and increased violence and crime in cities.

3 Midgley also made the chlorofluorocarbon (or CFC) gas to use in fridges for better results. Manufacturers also started using CFCs in spray cans for everyday use. However, the effect of this invention became known in the 1970s. One CFC molecule can destroy 100,000 molecules in the ozone layer. In 1985, British scientists found a big hole in the ozone layer above Antarctica, which shocked the world. The ozone layer protects us from the dangerous radiations of the sun. You can guess what may happen to our skin if we don’t have the ozone layer.