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I read an article in the same National Geographic Magazine (Feb
2004) that investigated a phenomenon I hadn't heard about yet: The fact that of
the amount of carbon we know humanity has released into the
atmosphere, more than half of it is "missing". As the article
states:
"Where is the missing carbon? "It's a really major mystery, if you
think about it," says Wofsy, an atmospheric scientist at Harvard University.
Forests, grasslands, and the waters of the oceans must be acting as carbon
sinks. They steal back roughly half of the carbon dioxide we emit, slowing its
buildup in the atmosphere and delaying the effects on climate."
It goes on to discuss how this is happening, and in the process of
reading it I learned something new:
"Both the waters of the ocean and the plants on land steal carbon
dioxide from the atmosphere. But they leave different fingerprints behind.
That's because plants prefer gas that contains carbon 12, a lighter form of
the carbon atom. The rejected gas, containing carbon 13, builds up in the
atmosphere. The ocean, though, does not discriminate, leaving the carbon ration
unchanged. Plants taking in carbon dioxide also change what they leave
behind. Because plants give off oxygen when they absorb carbon dioxide, a plant
sink would lead to a corresponding oxygen increase. But when carbon dioxide
dissolves in the ocean, no oxygen is added to the atmosphere...From these clues,
Tans [Pieter Tans, one of the scientists at NOAA in Boulder-- friend of
yours John K.???] and others have found that while the ocean is soaking up
almost half of the globe's missing carbon -- two billion tons of it-- the sink
in the Northern Hemisphere appears to be the work of land plants. Their appetite
for carbon dioxide surges and ebbs, but they remove, on average, more than two
billion tons of carbon a year."
I was unaware that there were isotopes of carbon and that plants
actually ignore one in favor of the other..... Does anyone have more information
on this? Do all species of plant prefer the same isotope?
Judith
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