In terms of CO2 emissions it doesn't matter which oil you burn, even burning gas will produce as much CO2 as burning the heavy fuel that we burn at sea. It has an effect on other pollutants such as sulphur dioxide, but not on CO2.
The only way we will produce less CO2 is to move away from the consumer society that we live in, which means no new car every 3 years, no new telephone every 3 months, not having 3 cars and 6 TV's per household etc. While society still demands to be fed it's consumer goods and still demands electricity to power them and more and more cars to drive around in, we will produce CO2 and no amount of hand wringing environmentalists, taxing politicians, or paperwork loving civil servants will do anything to stop, or even slow, the increase.