1.   But if the level continued its steady increase, he warned, the planet would warm beyond historic levels, disrupting the balance that made life possible.

2.   If you want a revelation sure to melt the ice caps, consider Gov. George W. Bush going on the record recently saying that the planet is warming.

3.   On the other hand, the planet has been warming somewhat.

4.   Some scientists believe that as the planet warms, melting ice caps will raise the oceans, endangering coastal areas and islands.

5.   The theory is that these gases can trap heat from the sun, causing the planet to warm.

6.   While most agree that the planet is warming, opnions differ about the root causes.