To know just what the effects of global warming will be in the future is extremely difficult, if not impossible.

Scientists use computer models to study the __1__ of global warming. These computer models have been fairly consistent in __2__ general future trends, but often __3__ greatly when looking at the specifics.

Some scientists say global warming has already been going on for a while. Others say that we do not have enough information now to know for sure. Despite the __4__, most scientists are convinced that greenhouse gases are __5__ the Earth. What they are still trying to figure out is how __6__ temperatures are rising, and what will happen as a result.

 The climate changes that will result from global warming are extremely __7__ to predict. The weather is determined by so many factors that it is often compared to chaos (complete disorder) by scientists. Changing the __8__ will likely have some effect on the planet’s weather, but just what that effect will be is __9__ impossible to predict.

If temperature do rise significantly, the most important __10__ would be that some part of the polar ice caps would melt, __11__ global sea levels.

The rise in sea levels would be __12__ for some places. Islands would __13__ , meaning their millions of inhabitants would have to move to other places. __14__ would occur along coastlines all over the world, forcing more people to move and ruining cropland.

In the case of major global warming and __15__ ice caps, some countries might simply stop existing. Global warming, if uncontrolled, could cause a major catastrophe.