Natural gas-fired water heating does reduce atmospheric CO2 emissions compared to electric water heating. Taking Florida data as an example, the statewide CO2 emissions from electricity production equal about 396 pounds per million Btu of electricity used at the home, while the CO2 emissions from direct use of natural gas in the home equal about 120 pounds per million Btu of gas use. Please see the EnergyGauge USA Pollution Analysis Help page for more information.