That fully depends on your definition of what the "reversed" state is. Will ecosystems adapt to the changed climate? Yes. Can temperatures even drop again? Sure. But species lost are gone forever. Ecosystems destroyed will never be the same again. Different ones can develop with enough time and stopping the human interference... But that is hardly "reversible". That is... natural systems covering up the damage. Going on. Not reversing it.
That fully depends on your definition of what the "reversed" state is. Will ecosystems adapt to the changed climate? Yes. Can temperatures even drop again? Sure. But species lost are gone forever. Ecosystems destroyed will never be the same again. Different ones can develop with enough time and stopping the human interference... But that is hardly "reversible". That is... natural systems covering up the damage. Going on. Not reversing it.