Most of us think of global warming as something that is bad for our planet. Every time you open a newspaper, there is an article about how the temperature on Earth is rising, causing floods, droughts and perhaps even earthquakes. Another common complaint is that winters used to be cold and summers hot, but now there isn't much difference between them.
Scientists say that global temperatures have risen 0.6 degrees centigrade over the last 140 years. The question is, should we see this as something unnatural? Climate change is not something new. When talking about global warming, we should look at more than the last century. This is because Earth has been in existence for billions of years, and during that time there have been both warm periods and ice ages.