From what I'm understanding this discovery doesn't help the current state of global warming:

> The study also finds that there are 46 percent fewer trees on Earth than there were before humans started the lengthy, but recently accelerating, process of deforestation. “We can now say that there’s less trees than at any point in human civilization,”

> loss of 15.3 billion trees each year... 5 billion of those may grow back each year, so the net loss is more like 10 billion annually.

> does not in any way change our understanding of the current rates of deforestation... “It does not say there’s more forest. It just says there’s more trees in the forest,” says Lovejoy.

> deforestation is making global warming worse... if we were living on an Earth with close to 6 trillion trees, rather than 3 trillion, climate change would be less severe.

It makes no difference. The amount of carbon in the atmosphere has not changed. If anything, this might mean that trees are less effective at reducing carbon than we thought, because there are more trees than we thought there were.

I think you're right, I read a few months back that grass is actually much more efficient in terms of reducing carbon. I'll have to look that up.

My understanding is that the earth's temperature is increasing within the model's prediction. Is it happening at the lower end?

Depends on if you look at the satellite troposphere data or the ground and sea thermometer data. The UAH/RSS satellite data say the troposphere hasn't warmed in ~19 years. The ground/sea based thermometers say we're all going to die in a fire (depending on which data revision you look at).