Energy and Changes in the Environment - Hydrogen and Fuel Cells: Advances in Transportation and Power - page 50

as there is in living matter, mostly in trees. But, there is several times more
carbon in the soils stored as dead organic matter called necromass. Bacteria
eventually help to decompose some of this necromass into greenhouse
gases such as methane, nitrous oxide (N 2 O), and CO 2 . The decomposition
speeds up if the soil gets warmer, emitting more greenhouse gases and
increasing the warming effect.
If global warming raises the temperature of surface waters and
carbon dioxide continues to build up in the atmosphere, the carbon dioxide
is less soluble in warmer water. The dissolved carbon dioxide can easily
move back into the atmosphere unless it is taken up by marine plants
or combines with a molecule of carbonate. But, the ocean's supply of
carbonate is limited and is replenished only slowly as it is washed into the
oceans by rivers that erode carbonate-containing rocks such as limestone.
By absorbing two billion tons of carbon from the atmosphere each year,
the ocean is depleting its buffer carbonate supply.
Creating carbon sinks includes planting new forests, which the
Kyoto climate treaty encourages. In China, the government has planted
tens of millions of acres of trees since the 1970s. This was done to control
floods and erosion, but one result has been to soak up almost half a billion
tons of carbon.
Young trees are hungry for carbon before they mature so one
technique is to keep a forest young, by regular thinning. U.S. forests have
increased by more than 40% in the last 50 years from 600 billion to nearly
860 billion. Standing timber is increasing at a rate of almost 1% per year in
the country.
While all the living matter in the oceans contains only about 3 billion
tons of carbon, ten thousand times that amount is dissolved in the oceans,
mostly in nonliving form. The carbonate sediments in the continental
crust and the ocean floor contain almost 70 million billion tons of carbon.
These are huge quantities compared to the atmosphere and living and
dead biota.
The ocean's natural uptake of carbon is in decline, scientists the
1980s suggested that large tracts of ocean could have green plants that are
the marine equivalent of forests and grasslands. These could be started
by treating the oceans with an iron compound. The plant growth would
soak up carbon and as the plants died and sank, the carbon in their tissues
would remain in the ocean.
Experiments have shown that treating with iron sulfate does cause
algae to bloom with patches tens of miles long. But when the extra plants