Relative clauses

I've wrote a few sentences including relative pronouns. I will be glad if you help me with probably mistakes.Thank you.
* There is no obvious reasons why global warming is increasing.
* I guess he is the one who can make our car fix.
* It was Japan where the earthquake happened last night.
* Wednesday morning is the time when we must meet each other.
* That is the car whose owner was J.F. Kennedy.
* There are the mistakes which are made a lot by you.