What is a Greenhouse Effect?

Interviewer:  Dr Clarke, global warming was the threat of the 1980s, but it seems to have fizzled out of people’s minds--why, do you think that is?
Dr clarke:  Yes, in a way you’re right. I think scientists have become occupied with the task of trying to find out whether it really is happening and, if so, whether it’s caused by human activity.
Interviewer:  A greenhouse effect is, after all, a natural phenomenon.
Dr clarke:  Yes, as we know, naturally occurring gases float above us, acting as insulators that prevent heat being radiated into space.
Interviewer:  And the fear is that the insulation might get thicker.
Dr clarke:  Yes, and because of this, the earth might get warmer.
Interviewer:  The latest prediction we’ve heard is that temperature will increase by about a third of a degree every ten years. What are your feelings?
Dr clarke:  Well ... this prediction is difficult to make. You see the global climate is the result of a web of influences. Who is to say that a simple action such as adding carbon dioxide to the atmosphere will not have several effects which might even cancel each other out?
Interviewer:  And I understand that the prediction is hard to verify whatever ...
Dr clarke:  Precisely.
Interviewer:  Why is that?
Dr clarke:. Because the earth’s temperature surges and subsides naturally. In fact the best way of detecting global temperature change is to measure the temperature of the oceans as accurately as possible.
Interviewer:  And this avoids the sort of seasonal fluctuations of the temperature of land mass.
Dr clarke:  Yes--in fact an understanding of the oceans is crucial to understanding how the global climate works. The ocean transports heat around the globe. It’s like a great reservoir of heat--a tiny change in sea surface temperature denotes a huge change in the amount of heat it is storing.