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Disappointed Trees
Tue Jan 27, 2004
Listen in RealAudio 
Hi, I'm Bryan Yeaton, and this is The Weather Notebook's weekly segment on Global Climate
Change.
Scientists have been hoping that forests might be able to soak up excess carbon dioxide, one
of the major greenhouse gases. Scott Ollinger, a researcher at the University of New
Hampshire, has developed a climate model which might put a damper on that theory.
SO: Well, what we try to do is analyze the combined effects of nitrogen deposition, carbon
dioxide increases in the atmosphere, and also tropospheric ozone pollution, and in this
particular case what we found is that the high concentrations of ozone that sometimes occur in
the lower atmosphere has a negative effect on tree growth and actually limits the amount of
carbon dioxide the trees are capable of taking up.
BY: You found that the effects of nitrogen and carbon can be somewhat absorbed by the forests,
but when you add ozone into the mixture, it doesn't work as well?
SO: Several analyses prior to this one have predicted that the deposition of nitrogen from the
atmosphere to the forest may actually be fueling additional carbon sinks. What we found is
that when you also consider the negative effects of ozone, that fertilization effect, by and
large, goes away. I think one of the things that these results imply, particularly in
combination to other results that other researchers have come up with recently, is that the
long-term effect of forests on carbon dioxide levels in the atmosphere don't seem to suggest
that they will serve as the miraculous carbon sink that previously some people had
hoped.
Ollinger adds that, even when CO2 is absorbed by the trees, it doesn't just disappear. More on
that next week.
Our Global Climate Change Series is funded by the New England Science Center Collaborative and
the Roy A.
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