As the week comes to a close, a few tidbits to ponder on a sunny Sacramento afternoon…

* Homeless, But Where?: Some new estimates on the size of the nation’s homeless population are the focus of debate here in California. Meantime, that same estimate finds more without a home in Fresno… than in San Francisco. On this weekend’s newsmagzine edition of The California Report, we examine both topics… with a look at law enforcement raids on homeless encampments in Fresno, reported by my colleague Sasha Khoka.

* White House Hopefuls: Presidential candidates are on their way back to the Golden State over the next few days: Democrat John Edwards is in Fresno today, Berkeley on Sunday, and LA on Monday… Hillary Clinton is in LA on Saturday… and Republican Rudy Giuliani also heads to LA on Monday.

* Yes, That’s How Much It Weighs: Several emails have arrived in my box questioning the accuracy of the math in this week’s posting (and this week’s radio piece) on just how big of a carbon footprint is left by Governor Schwarzenegger’s travels in a Gulfstream jet.

These readers and listeners doubt that a gallon of jet fuel can be responsible for 28 lbs. of carbon dioxide emissions. “The right numbers should be used when criticizing [the governor’s] actions,” wrote one person. Another asked: “Did you do some research on what the environmentalists said, or did you just use their information ‘as is’?”

We did, in fact, do research. The layperson’s explanation: the actual jet fuel is not the only source of fuel for the engine itself. It also uses gases in the air as fuel– namely, oxygen. Thus, a carbon will attach itself to two oxygens to create CO2. And because oxygen is a little heavier than carbon (16:12 atomic weight), the mass of CO2 emitted is actually heavier than the original jet fuel.

Our numbers were based on data from the U.S. Department of Energy, plus an additional calculation from the Sierra Club suggesting that the CO2 emissions should also include the emissions created by the refining of each gallon of jet fuel. Today, we checked our math with faculty members at both CSU Chico and UC Davis. Both agreed with our number… 28 lbs. of CO2 per gallon of jet fuel… and one even opined that the number was probably “conservative.”