Since global warming appeared during the last decade as a serious environmental issue, it has been the subject of a lot of debate. Global warming is defined as the warming of the earth by greenhouse gases emitted into the atmosphere naturally or by mankind. But there are many questions about global warming, from its causes to its full effects. 

Many people even question whether or not global warming exists. And if global warming does exist, people question why it exists. But there is one fact that no one has questioned - the surface temperature of the earth has increased 0.45 - 0.6 degrees Celsius in the past century. 

 
Is the increased temperature something we need to worry about? Well, there are two different viewpoints. The believers in global warming think that the increased temperature proves that global warming exists, and that it's a significant problem that should not be taken lightly. 

Skeptics of global warming believe that the increased temperature is a natural phenomenon, and that if global warming does exist, it's not something to be worried about. What makes this debate so interesting is that there is valid scientific data to prove either side. 

Global warming has been proven and disproven using computer climate models. Believers in global warming use them to show that in the next century there will be a significant rise in the Earth's temperature, and an increase in the height of sea level. Global warming skeptics suggest that the models are not entirely based on fact, and that they can not be trusted. 

There are many arguments for and against the existence of global warming. We'll take a look at some of the arguments for both sides on the following pages, starting with the believers in global warming.