"Carbon footprint" is a measure of an individual or company's impact on the environment in terms of global warming.
It is a calculation of the amount of carbon dioxide that is produced by a person from their everyday or working lives.
The main activities that increase emissions and therefore carbon footprint include electricity use, home heating, car travel and air travel.
Other factors that can also be included to calculate a carbon footprint include "food miles", which is the distance that the food a person consumes has travelled.
Another element is the level of consumption of new consumer goods by an individual.
Calculating your carbon footprint can be quite complicated, but there are a number of online calculators to help you. One of the best in terms of Irish residents is found on www.grian.ie, the website of environmental campaign group Grian.
The Irish Timesestimated the transport carbon footprints of Government Ministers through a range of calculations. For car use, an average annual mileage figure was obtained and this was combined with the "emissions rating" of each individual car to obtain the tonnes of carbon dioxide produced.
For commercial airline travel, The Irish Timesattached a figure of 180 grammes per kilometre travelled by each Minister.
Private jet and helicopter emissions were calculated by the fuel per minute associated with the two Government jets and the Alouette III helicopter.
What is carbon offsetting?
Individuals and governments can offset emissions by paying agencies or charities to ensure reductions in other areas, such as through the planting of trees or paying for energy efficient lighting in a developing country. It is not without controversy, however, with claims that many schemes do not ensure real cuts.