Three times this winter I've turned the crank on my 1994 Ford Escort and had it not start right up. Admittedly once was a dead battery and once was a defective battery but still, I'm considering the reality that one of these days I'll have to overcome my natural lethargy actually replace the thing....so, I've been reading up on new cars...and carbon footprints...and have been trying to work out to what extent getting a hybrid is an effective way to save the planet and to what extent it's just sort of cool.
Somewhat surprisingly, the nicest carbon-footprint calculator I found was at the EPA. According to them, replacing both my cars with something that had better than double the gas mileage would save about 2300 lbs of CO2/year - but I'd save more with a either newer furnace, or with new windows for my house. I'm probably atypical here, as together Susan and I drive about 100 miles a week, but still, I was pretty surprised.
Another data-point came up today in Low-tech Magazine: according to them, at least, the carbon cost of manufacturing the 8m^2 of solar panels needed to power a house is between 60,000 and 940,000 kgs of C02 - and according to the EPA this is the same carbon cost as between 20 and, um, 300+? years of electricity use for an average family of 4. Of course, this could be way off base, but it seems to me that we need to set up either some sort of marketplace mechanisms to allocate CO2 savings efficiently - just following the trends may not get us there.