Web edition: November 18, 2007
Print edition: November 24, 2007; Vol.172 #21 (p. 335)
Although multinational agreements on global warming try to spread the burden among all nations, data from the MILAGRO project in Mexico City ("What Goes Up," SN: 9/8/07, p. 152) suggest that the major responsibility for excess production of greenhouse gases and other pollutants lies with the megacities, which constitute a rather small number of culprits and ones that not all nations possess. Perhaps global, and indeed national, initiatives to control air pollution should focus on compelling these megacities to curb their waste.
James M. Bryant
The news is filled with observations of our species' role in global warming and in the depletion of fisheries, arable land, fresh water, and fossil fuels ("Invasive, Indeed," SN: 10/13/07, p. 235). Yet I seldom hear the size of the human population cited as a driving force behind these problems. The easiest path to reducing our environmental footprint would be to slow our population's growth rateafter all, it takes a foot to make a footprint. Has our evolutionary drive to multiply also endowed us with a blind spot when it comes to recognizing the peril of our numbers?
Ultimately, Malthus was right: No technology can save us from unfettered population growth on a planet with finite resources.
Silk Hope, N.C.
Mild vibration encourages precursor cells to turn into muscle and bone ("Good Buzz: Tiny vibrations may limit fat-cell formation," SN: 10/27/07, p. 260). This seems like something NASA could use to keep astronauts fit.
Santa Rosa, Calif.
"Platinumfree fuel cell" (SN: 10/20/07, p. 253) describes hydrazine hydrate as a benign and cost-effective alternative fuel to hydrogen. But hydrazine hydrate is a fuming liquid that is toxic, very corrosive, and can decompose explosively. In a reaction with hydrogen peroxide, it powered the German V-2 rockets in World War II.
Carl F. Guerci Jr.
Severna Park, Md.