For which task you wrote this essay? Is it for IELTS? or TOEFL or some class assignment. It's good to mention the task so that we can provide you with more task related comments. :)
they are very useful for me.thanks you very much
Yes, septem1821 has provided a very good feedback for you. Thanks septem1821.
1) pollution is one of the causes of environmental instability and the task is about the environmental protection. so, I think you should not have used pollution in the introduction part.
This is a good point. You need to highlight the key point of your prompt and introduce the same. The key point here is that people do not pay enough attention to environmental protection. So start your introduction with an effective hook that talks about the environment;The survival of all living beings depends upon the environment.
Then tell the Background of this issue;Therefore, it is our responsibility to protect the environment. However, the people pay very less attention in this regard.