> Isn't that the critical point? Of all our environmental problems, atmospheric CO2 is the biggest one, right?

Energy is important, but the energy consumption of a grocery bag is small compared to the energy consumption of most of the things in the grocery bag, and if you drive a car to the grocery store, the energy consumption of the car for the roundtrip (~0.3 kWh per mile).

I'd say for grocery packaging the ecological impact should be the bigger concern.

Honestly the solution is easy, change the $0.10 grocery bag surcharge to $1.00 and people will stop using single-use grocery bags tomorrow. $0.10 is not enough for people to care.