Fact: Using your car’s air-conditioning can have an indirect impact on climate by increasing fuel consumption, which in turn increases CO2 emissions.
Using your air-conditioning requires some additional fuel use by the engine to power the refrigerant compressor when the system is on.
The amount of carbon-dioxide (CO2) produced in a vehicle’s exhaust is proportional to the amount of fuel used and CO2 is also a global warming gas.
Just how much additional fuel the use of air-conditioning requires varies dramatically with such factors as the vehicle itself, driving speed, wind conditions and temperature.
Various studies suggest the range of that effect is typically between 1 and 10 percent, with the greatest increase in consumption in urban stop-and-go driving and the least effect at highway speeds.
Rolling the windows down rather than using the air-conditioning also has a negative effect on fuel-consumption at higher speeds, because of the additional aerodynamic drag created so it may or may not be a worthwhile alternative.
Whether or not to use your air-conditioning comes down to a choice between personal comfort and a modest increase in fuel-consumption and consequent CO2 production. The choice of yours.