In the last few years we have seen some very hot summers. The summer of 2006 was the hottest on record. Its true that one really warm year doesn't prove that the earth is getting warmer, but there have been an unusual number of hot summers recently. The summer of 2007 might not have brought scorching temperatures to the UK, but many people died from heat stroke across other parts of Europe. Since 1991 there have been ten record-breaking summers. And since 1981 there have been twenty! This doesn't mean that each year will get warmer, but it shows that over time the trend is for higher temperatures.
Myth four - we shouldn't trust scientists, they can't even get the weather forecast right