Actually oceanic phytoplankton aree the 'lungs of the planet', ocean covers 70% of the surface and about 30% of the earth surface receiving sunlight at any one time is ocean. Continental forests are worth a lot, but as for being the lungs, well they hardly rate as being the bronchial tubues!
I would imagine that if the rainforest goes, the atmosphere will be burdened with even more CO2. This in turn will mean that more CO2 is absorbed by the oceans thus raising acidity levels. In turn this may start to kill off the phytoplankton thus depeleting this major carbon sink? Double whammy.
I've read a few times on other forums that as we are putting a tiny % of CO2 into the atmosphere what's all the fuss about? The way that I see it is that we are tampering with the atmosphere and putting changes into place that we will not be able to stop. Positive feedback loops will amplify our initially small addition of CO2 and before you know it the climate is out of control. It's like pouring sugar into your petrol tank, really easy to do but once you've done it the car is screwed and you are going to have to make a huge effort to get it back to working condition.
Can't someone get it through to the heads of the people that run this crazy show that it's better not to pour the damn sugar into that tank in the first place?