I absolutely adore the whole global warming/manmade climate change thing. The story has a mythic grandeur about it which is wholly lacking from most of the nonsense which one sees in the newspapers. This is essentially the tale of how Man’s wickedness and greed brings down a worldwide catastrophe upon the entire race. It is the story of the Biblical deluge, which was precipitated by the same sins, with much the same consequences; i. e. rising sea levels!
Those of us with long memories might perhaps recall the days forty years ago when the scientific journals were full of the danger of manmade global cooling. This was being caused by pollution from power stations and factories. Particles of smoke and dirt were filling the upper atmosphere and preventing the light from the sun reaching us. The evidence was compelling; global temperatures falling since the end of World War II, cold water fish moving south into temperate waters and many other things. Then we had the population explosion which would cause the end of civilisation, the exhaustion of oil and other natural resources by the year 2000, the threat of nuclear war and, best of all, the Nuclear Winter. Remember that one? It was great; a combination of nuclear war and Ice Age. Also to be brought about by our wicked and sinful nature!
Still and all, this is nothing to the purpose. Any child taking science GCSEs needs to know a little about this subject, even if it is a pack of fairy stories for credulous and gullible fools who are unable to think for themselves. Here are a few practical ways of demonstrating to children how the mechanisms of the climate work.
The easiest way to show the practical effects of the Greenhouse Effect is just to set a transparent plastic cup on a sunny lawn, trapping some air beneath it. Leave it for an hour of so and then get your child to check the temperature. It will be as hot as an oven. Explain that without this Greenhouse Effect, life on earth would be impossible. The planet would alternately bake and freeze. If not for the water vapour and carbon dioxide in the air which traps the heat, we would be in a sorry state indeed! You sometimes hear foolish people talking about the Greenhouse Effect as though it were a bad thing. Without it, life on Earth could not survive.
Now fill one transparent plastic cup with earth and another with water and set them side by side on a sunny window sill. You will find that the earth heats up very fast, but cannot retain the heat. As soon as you remove it from the sun, it cools very quickly. The water, on the other hand, heats up slowly, but retains the heat for a long time. This keeps the temperature of the planet fairly level. You could talk about heat-sinks and the Gulf Stream which keeps this country warmer than other European countries on the same latitude.
As every schoolchild knows, the Arctic ice is melting and this will not only drown a load of cute baby polar bears, it will also flood low-lying cities anywhere else in the world. Disaster! Easy enough to prove to your child that this is a lot of nonsense. There is no dispute that the ice in the Arctic might be at risk from record levels of melting. There is also little doubt that except in one or two atypical places, the Antarctic ice is growing thicker, so it’s only that pesky Arctic ice that we need to worry about. What would happen if all the ice in the Arctic melted tomorrow? It would surely have some effect upon sea levels; after all there is an awful lot of ice near the North Pole, isn’t there? Well, that’s right. There is loads of ice and no land at all; it is all floating in the water. To see what would happen if it all melted, let’s make our own Arctic Ice cap!
Take the largest clear glass bowl that you can find; the bigger the better. Fill it half full of water and then dump in as much floating ice as you can. Lots and lots of ice cubes, chunks of ice from elsewhere; just make sure that it is all floating, like the real Arctic ice. Now mark the level of the water and let the ice melt. You might expect that the water level would rise, but you would be dead wrong. Even when all the ice has melted, the water level is exactly the same as it was before. This is because ice expands when it freezes. Which is of course why it floats in water. You have now shown that if all the ice in the Arctic were to melt, it would make no difference at all to the world’s sea levels.
What might make a difference though, if the planet were to heat up, is thermal expansion. You can demonstrate this on the kitchen window-sill as well. Boil some water and then let it cool for a few seconds. Fill a clear glass jug with the very hot water and mark the level on the side. Now cover the top of the jug with tin foil or clingfilm, to prevent evaporation. You will find that as the water cools, the level goes down. In other words, hot water takes up more room than cold. If the oceans were to warm up, then sea levels would indeed rise. Not by very much of course, you can easily do the sums for this, but warming would cause a slight rise in sea levels.
The great advantage of home education is that you are free both to spend the day in experiments of this sort and also to avoid the majority views of society if you should wish to do so. This is very valuable, because it means that you and your child can learn to think for yourselves, without being browbeaten by the prevailing ideologies of the day. No wonder some people don’t like home education and feel that it is liable to produce dangerous mavericks and freethinkers! Not really all that good for society in general, perhaps.