The experiments with mice infected with the 1918 influenza virus are important but not surprising ("The Bad Fight: Immune systems harmed 1918 flu patients," SN: 9/30/06, p. 211). John Barry's The Great Influenza: The Epic Story of the Deadliest Plague in History (2004, Viking) explains that many, perhaps most, of the victims were killed by the overreaction of their immune systems. This may be why most of the victims were young, with strong, young immune systems.
San Diego, Calif.
I was surprised you didn't mention the effect of salinity in ocean water ("Mystery of the Missing Heat: Upper ocean has cooled slightly in recent years, despite warming climate," SN: 9/30/06, p.213). Warming climate has melted much of the glaciers, bringing fresh water into the North Atlantic. That water isn't dense enough to sink and carry on the conveyor belt that usually brings warm currents from the tropics. This slowing of the conveyor belt happened during the Little Ice Age, and apparently, it's happening again.
Bella C. Chiu
Isn't it likely that the accelerated breakup of polar ice holds the key to the missing heat? Massive amounts of heat are absorbed by the solid-to-liquid phase change when ice melts, and recent observations have shown a striking reduction of ice thickness.
Grand Junction, Colo.
Perhaps the heat is going into the atmosphere and is the origin of what we measure as "global warming."
Cedar City, Utah
As far as scientists can tell, top-layer cooling of the world's oceans isn't an effect of melting ice in the polar regions. Some of the heat may be warming the atmosphere, scientists say. However, much of the missing heat remains unaccounted for.—S. Perkins