Was just reading that if we all gained weight the increased earth mass would increase the radius of the orbit around the sun leading to some cooling. Some scientist has calculated that a 5% increase in average BMI will cool the planet by 1.14 degrees.
I've also been told that if I change to a diesel engine I will add more sulphur dioxide to the atmospher which further adds to the cooling.
I'm doing my bit.
(incidentally - people keep comparing the Australian CO2 emissions with other countries per head of population - it should actually be done per unit of land area - we have much more air in Australia per head of population so our emissions have less effect because there is much more air per person)