With all the recent media attention on global warming, some of you may be wondering what causes it.

The Mechanisms

Energy reaches the surface of the earth from a number of sources: the sun, geothermal energy, and non-renewable energy generation by humans. The sun is by far the largest source of such energy, and the rate at which solar energy reaches the earth is amazingly constant.

The problem is the rate at which energy escapes from the earth. Greenhouse gases (mainly carbon dioxide and methane – methane is a much more powerful greenhouse gas than carbon dioxide) in the atmosphere slow down the rate at which energy can escape from the earth (the greenhouse effect), and cause warming. Some solar energy is also reflected by the oceans and most especially by snow and ice, which is one reason why scientists are so concerned about the loss of polar ice.

The increase in the levels of greenhouse gases is being caused by the human race burning fossil fuels (oil, gas, coal and wood), and by the release of methane (melting permafrost, caused by global warming, and leaks of gas from gas wells and pipes).

The Root Cause

Of course, humans have been burning fossil fuels since the discovery of fire, but it wasn't a problem until recently.

The thing that has changed, and made a tolerable pollution problem into a crisis, is that the population has increased so dramatically: world population is now around seven billion, and still growing. Global warming is caused by there being too many people. Even if the nations which contribute most to greenhouse gases (Australia, China, the USA and Western Europe) were to immediately reduce their pollution levels to amounts in line with the rest of the world, we would still have a global warming crisis.

What Can You Do?

There is a saying: if you are not part of the problem, then you are part of the problem. It is time for all of us to take action to deal with the problems that we have caused. Global warming is not someone else's problem; it is yours and mine.

The most important single thing that people can do is: have fewer children. People are the cause of pollution. Children born now will be 36 years old by 2050 (the latest date by which the predictions in the IPCC report are expected to come true), by which time they will be creating their full load of greenhouse gases and other pollution. What gives you the right to take away the right to life and to damage the quality of life of me and my children, by having a large family? What gives you the right to make other species extinct, by having a large family?

Some of you may argue that you have religious grounds for having large families. Do you really think that you will be rewarded in the afterlife for helping to destroy our planet?

There are other things that you can do, which will have faster effects, but will only buy us a little more time if the population of planet earth continues to grow. These include more recycling, and better energy use (less energy, and more of it from renewable sources). From a global warming perspective, energy from nuclear, wind, hydroelectric and bio-fuel sources are good; gas-guzzling cars, coal and oil, air-conditioning, inefficient household appliances and inefficient lighting are not good.

I already live a much lower impact life than most: I have high-efficiency lights throughout my home, I have modern high efficiency (energy and water efficient) kitchen appliances, I do not have a car (I use public transport and use my bike), and I recycle a lot (metal, plastic, glass, paper, electrical/electronic equipment, etc.). I know that I need to do more. What are you going to do?