Why do I get jealous over a girl even though I don't want to be with her at all?

 Both sentences are correct, and they have the same meaning. The phrase "getting hotter" is synonymous with the phrase "warming."

The first sentence, "The planet is getting hotter year by year," is more direct and concise. The second sentence, "The planet is warming year by year," is more formal and scientific.

Which sentence structure you choose to use will depend on the context in which you are using it. If you are writing a scientific paper, you might choose to use the second sentence. If you are writing a news article or a blog post, you might choose to use the first sentence.

Here are some examples of how the two sentences might be used in different contexts:

Scientific paper: The planet is warming year by year, primarily due to human activities.

News article: The planet is getting hotter year by year, and scientists are concerned about the long-term effects of climate change.

Blog post: The planet is warming year by year, and it's important to take steps to reduce our carbon footprint.

Ultimately, the best way to choose which sentence structure to use is to consider the context in which you are using it and the tone you want to convey.