Private military contractors under scrutiny Blackwater Worldwide is perhaps one of the higher-profile private military contractors in Iraq, but they're not the only one. Blackwater's involvement in the killing of 17 civilians in Iraq and the subsequent investigations highlight the problem holding soldiers for hire accountable when things go wrong.9:06 a.m.
Mark Hemingway: Staff reporter for National Review Online.
Steve Fainaru: Foreign service reporter with the Washington Post.
Fighting global warming by manipulating the climate Mirrors in space? Dispersing sulfur into the stratosphere? These are just some of the ideas that have been suggested as a last-ditch effort to combat global warming. But some are concerned that manipulating the climate could be disastrous.10:06 a.m.
Daniel Schrag: Professor of earth and planetary sciences at Harvard University, and director of the Harvard Center for the Environment.
Ken Caldeira: Climate scientist with the Carnegie Institution's department of global ecology.