I think carbon-eating trees are only part of the solution. We already have carbon-eating trees; all that coal and oil didn't just come from dinosaurs. The problem is that the output of trees is so useful, we don't have to willpower to cut them down (or even just rake up all the leaves each fall), store them in a cave somewhere, and forget about them.

We really need the carbon in a form that doesn't decompose and is more useful than wood. Diamond would be great...

We also already have genetically engineered carbon eating plants. Most of our agricultural crops have been genetically engineered (using selective breeding or molecular biology) to be much better at getting CO2 out of the atmosphere to produce carbohydrates than their wild counterparts. Unfortunately it seems that taking CO2 out of the atmosphere is like taking pee out of a swimming-pool: it's possible, but takes a lot of energy. Most crops compensate the increased energy cost for carbon uptake by reducing their defences against pests and droughts, which means they need to be subsidised with pesticides and irrigation (today produced mainly using fossil fuels).

It would be great if we could design trees that catch more CO2 than they need but, being an evolutionist, I'm not holding my breath. I imagine that even a small energetical efficiency increase would be a big evolutionary advantage and that plants are pretty close to their theoretical efficiency limit.

Of course IANAPNAPP (I Am Not A Physicist, Nor A Plant Physiologist), if you are please enlighten me.

What if they ate away all the Carbon, leaving non for food plants to grow? It might not be as simple as the paper made it out to be...

Have you see Paul Stamets's talk about mushrooms on TED? He proposes -- and as he demonstrates, justifiably so -- using fungi as an effective measure against global warming. It's so ridiculously awesome that if he starts a mushroom company I would want to work there.

Um. Trees ARE carbon.