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Science Frontiers ONLINE No. 131: SEP-OCT 2000 |
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Green Misconceptions
More trees may be good for the environment in the tropics, but the reverse is true in lands that are covered with snow most of the year. This is be-cause snow reflects much of the impinging solar energy back into space. If these northern lands were heavily forested, much of the solar energy would be absorbed and converted into heat. Climate-modellers confirm that sunlight-reflecting snow is better for the environment than trees.
(Anonymous; "Reflect on It," New Scientist, p. 19, May 13, 2000.)
Hydroelectric power is clean. Although widely proclaimed to be among the cleanest energy sources available, some hydroelectric powerplants actually con-tribute more greenhouse gases than large coal-fired plants!
Submerged vegetation is the problem. When it decays, it releases greenhouse gases---in quantity. The forests first submerged by the reservoirs behind the
dams contribute gases for only a few years. Most of the troublesome biomass is fed into the reservoirs from upstream. Compounding the problem are the vast areas of stagnant water behind many hydroelectric dams. There, in the absence of dissolved oxygen, the rotting vegetation generates methane, which is a much more potent greenhouse gas than CO2.
(Pearce, Fred; "Raising a Stink," New Scientist, p. 4, June 3, 2000.)
Other Sites of Interest
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