Maury McCown, Flickr
The problem is, climate change wasn't the reason these forests were protected. The key issue here, which the author fails to name, is additionality. If a forest was going to be saved anyway (or was never threatened in the first place), should forest managers be able to sell carbon credits to polluters? Or say, in the case of a large hydropower plant in China, should polluters be allowed to purchase credits from the dam even it was operational well before carbon credits were even a possiblity (as so many CDM hydro projects are)? If these projects were going forward without carbon credits, they're non-additional.
Which in my book means not adding to the overall emissions reductions we need in order to avoid severe climate instability. Which means postponing real climate action until it becomes unbelievably costly, in both human and financial terms.
Recognizing the value of ecosystem services (like the ability of plants to remove CO2, or wetlands to purify water) is an important component in preserving and appreciating our environment. But just paying for them shouldn't be an excuse for polluters not to clean up their act.