A.I. Explanation:

Option 1: "To call for the action to combat global warming."

Explanation: The author emphasizes the urgent need for humanity to prepare for and adapt to the effects of global warming, indicating a call to action. The phrase 'Science leaves no room for doubt: Climate change is the existential threat of our time' underscores the seriousness of the issue and the necessity for action.

Option 2: "To state the fact of climate change."

Explanation: While the text does mention climate change, it does not merely state it as a fact. Instead, it focuses on the implications and the need for action, making this option too narrow and incomplete.

Option 3: "To state the fact of global warming."

Explanation: Similar to Option 2, this option only addresses the existence of global warming without acknowledging the author's emphasis on the urgency and the need for action. The passage goes beyond stating facts to highlight the consequences and the necessity for a response.

Option 4: "To provide solutions for climate change."

Explanation: The text does not offer specific solutions for climate change; rather, it discusses the effects and the importance of understanding these changes. This option misrepresents the author's intent, which is more about raising awareness and calling for action than providing solutions.