Answer:
1. Explanatory introduction: In this type of introduction, the author can explain what global warming is, in a few words. In this way, he begins the essay with a generalized explanation of the topic that he will develop during the essay.
2. Chronological introduction: The author can begin by explaining how the world we know came to global warming, showing how the climate evolved from a state with a low risk of global warming, until today.
3. Personal introduction: The author can tell a personal story of how the global warming affected some of his experience, with this, he manages to start the essay showing a real impact of this climatic phenomenon.
Explanation:
The introduction is a very important element of the text and manages to announce a subject that will be addressed and detailed throughout the text. This element is important to situate the reader or the audience about what will be addressed and thus create an organized and functional structure throughout the text.
There are several ways to write an essay and the author must choose the one that best suits his writing style and the audience he wants to reach, as well as the essay's objective.