The carbon footprint of a lamb chop has been revealed by a study which found that every 100g of New Zealand lamb exported to Europe creates 1.9kg of greenhouse gas emissions.

The study is relevant to New Zealand shoppers because most of the emissions - 80 per cent - are generated on the farm and just 5 per cent by shipping lamb to Europe.

Shoppers' behaviour accounted for 12 per cent of emissions but if transport to and from the supermarket was counted, that would have risen to 19 per cent - nearly four times the emissions taken to get the lamb to Europe, said researchers.

AgResearch scientists tracked lamb from paddock to plate, measuring the gases produced by the sheep, cooking, refrigeration and transport.

They found shoppers could cut their impact by choosing chilled meat rather than frozen and avoiding microwave defrosting of meat.

Lamb's greenhouse gas footprint was measured in CO2 equivalents, although only a small proportion of the emissions were actually CO2 - the majority was methane from cow burps and nitrous oxide from sheep excrement on the soil: short-lived but potent greenhouse gases which are multiplied several times over to get the equivalent in CO2.

Meat Industry Association, Ballance Agri-Nutrients, Landcorp, and the Ministry of Agriculture and Forestry paid for the study because they wanted to find out where in the lamb's supply chain they could most easily cut greenhouse gases.

Report lead author Dr Stewart Ledgard said it was the first detailed study of the carbon footprint of a New Zealand meat product to cover the whole lifecycle.

The study was done in accordance with UK carbon labelling standards, so the information can be used on carbon footprint labels that are being rolled out by British food chains.

Lamb producers will welcome the finding that so little of lamb's carbon footprint is from shipping, something that may be used to fight allegations that "food miles" drive up the environmental cost of New Zealand exports.

Unfortunately for farmers, the biggest portion of gases were also some of the most difficult to cut: livestock emissions, which the Government is heading a major international research mission to reduce.