As bad as it seems sometimes, mankind has not dealt the death blow to our ecosystems, yet! Most of the real damage has been done by corporate entities who seem to show no mercy to the environment in favor of the all mighty dollar. But, fortunately in the US and around the world, average citizens are the ones who enjoy the benefits of healthy ecosystems the most and eventually will stop doing business with those that are destroying it. The growing awareness of everyday people will save our ecosystems from permanent damage.
We'd never be able to repair, completely, what has been done to the ecosystem. For example, many species have gone extinct and can't be brought back. But if we were all to change our lifestyles completely, we could certainly work to create more of a balance. However, it's also unrealistic to believe that everyone will change their current lifestyles in order to do so. So, while it could be possible, it's not at all likely.
Anybody who denies the existence of man made global climate change or any human-induced alteration to the climate has clearly not read a substantial amount about the issue - this is a given. Still, the idea that the climate is somehow 'damaged' shows a severe short sightedness when thinking about the planet and its long term (billions of years) history.
I do not believe the damage that we have done to our ecosystem is salvageable. I think whatever damage we have done will have to slowly be repaired by the planet, if it is even capable of doing that. I do not believe we have enough knowledge about the situation to assess the level of damage or its effects, so we're better off to become as environmentally friendly as possible.
The damage to our ecosystem is not salvageable. I believe that it is only getting worse and will continue to do so. You would have to get a lot of people on the same agenda to do anything about the damage that is already done. It would not be cost-effective to do so and not enough profit for the government to do so. You would have to get people to give up driving and doing other things that pollute our atmosphere and I do not see that happening anytime in the future until it is way too late.