Google tells me that carbon dioxide, the chief culprit in global warming, is measured by its atomic weight.

One atom of CO2 weighs twice as much as one atom of carbon.

Adult humans, breathe out 2.5 pounds of CO2 each 24 hours. An active person expires up to eight times as much as a sedentary person.

An average passenger car emits 4.6 metric tonnes of CO2 per year.

Four years ago, New Zealand boasted 1,000,000 such cars, and rising rapidly. Calculate the sums (not my strong point) and the number of CO2 atoms put into the air by humans here and worldwide, must be horrendous.

Google also says that the ice age cycle includes the interglacial era of 12,500 years. Earth has already passed through 11,000 years of this period ending with some high temperatures, and problem phenomena.

Can we afford to wait for the next ice age to begin? Really, there is no option.

M Whitwell, Judea