A carbon footprint is measured in tonnes of carbon dioxide emitted by an individual or company in their ordinary daily lives.

There are numerous ways of calculating carbon footprinting. This is directly related to the amount of natural resources consumed, increasingly used or referred to as a measure of environmental impact.

Carbon dioxide is recognised as a greenhouse gas, of which increasing levels in the atmosphere are linked to global warming and climate change.

For the purposes of working out the carbon footprint of government ministers flying to various destinations for St Patrick's Day celebrations, the 'Sunday Tribune' attached a figure of 180 grams per kilometre travelled by each minister.

Flight distances were calculated using an internet site that measures the distance from Dublin of each of the ministers' destinations.

What is carbon offsetting?

Each of our everyday actions consumes energy and produces carbon-dioxide emissions - for example, taking holiday flights, driving cars, heating or cooling our homes.

Carbon offsetting is a means of compensating for the emissions produced with an equivalent carbon dioxide saving.