I can’t give you a paragraph to use in an assignment, that would be plagiarism, but I can get you on the right track.
I don’t know what assignment you’re working on specifically, but climate change is a very broad topic. Is there any chance you could narrow it down? Maybe you could argue that climate change is happening, or propose a solution for climate change.
Once you have some direction, you’re ready to start researching. If you have material given to you by your teacher on climate change, like a textbook or a handout, start with that. Then do further research if needed.
When you sit down to write, try not to worry about making your writing perfect on the first go. Just get your thoughts down. You can fine tune them later.
Good luck!