Scientists who study the climate are still arguing about how fast the earth is warming and how much it will warm, but they do agree that the earth is warming and that it will keep warming if we don't do anything about it. Scientists agree that the burning of fossil fuels   like oil and coal cause greenhouse gases to escape into the air and that these gases are causing most of the warming. Another cause is deforestation (cutting down trees) . Trees _ carbon dioxide, one of the greenhouse gases, from the air. There are already some changes happening because of global warming. Sea level is rising and some animals are already moving to new homes. It's already too late to stop global warming completely. If the warming gets worse, as scientists expect, there may be some kinds of plants and animals that is disappearing because they can't move to new homes. There may be more storms and floods. Sea level may rise so much that people have to move away from the coasts. Some areas may become too dry for farming. Global warming is a very difficult problem to fix. People are having a hard time agreeing on what to do about it. For example, everyone agrees that wasting energy is a bad thing to do. But some people think that the federal government   should make laws about it, while other people think it should be up to each person or business to decide what to do. Many states and businesses in the United States are not waiting until the federal government decides what to do. They have already started working on the problem. What is the best title of this passage?
The reason for global warming How to stop global warming The changes to the world The global warming