I need some help to check grammar please!

I was writing a script but I'm curious about some sentences
Please check each sentence the grammar or change it into native style sentence.

-If anything is concerned with environment, that's valuable.

-If anything is concerned with environment, it's valuable.

-Let's see how it's so important.

-In Korea there will no more be 4 seasons.

-In Korea there will be no more 4 seasons.

-Quiet many things changed for the worse.

-People don't seem to sense this danger in the flesh.

-It will support your purchasing hybrid cars.

-In the UNFCCC reference says, blabblabblab