of the experiment, the 1997 and 1998 growing seasons, we found a 25 percent growth rate increase in the loblolly pine exposed to high carbon dioxide in the forest. Whether or not that continues is a real source of interest to us. NARRATOR: So is the coal industry right? Will this enhanced growth help suck up the excess CO2? Only, say scientists, if the CO2 stays out of the atmosphere. PIETER TANS, Nat'l Oceanic and Atmospheric Adm.: The forests might sequester CO2 for 50 years, 100 years. And then at a certain point, it comes more or less into balance because enough organic matter in the forest has been built up that decay starts to catch up with photosynthesis. If we chop down the old tree, we have to make sure that most of that tree is put into a usable product that has a long life. And what happens then? Eventually the lumber rots or gets burned. NARRATOR: Eventually, within a century or less, the carbon locked in wood will find its way back into the atmosphere as CO2. And there's another reason for believing that plants alone can't absorb all the CO2: the vast size of the fossil fuel reserves. PIETER TANS: When you look at the amount that is potentially available in coal, it's such an overwhelming amount. If you were to store all that in plants, the terrestrial biosphere would be four or five times the mass that it is now. Hard to conceive how plants