Diets and Methane Emissions Eimear Leahy Seán Lyons Richard S.J. Tol

Motivation Agriculture is responsible for 30% of the world's GHGs (CO 2, N 2 O, CH 4 ) “producing 0.25kg of mince releases as much greenhouse gases to the air as driving an average car for 14km” “going vegan is 50% more effective than switching to a hybrid car in reducing greenhouse gas emissions” “if every American skipped one meal of chicken per week and substituted vegetarian foods instead, the carbon dioxide savings would be the same as taking more than a half-million cars off U.S. roads”

Motivation ctd Meat Production alone = 18% of all GHGs (UNFAO, 2006) Livestock accounted for 92% of all methane emissions from agriculture in the USA in 2003 (bacteria from ruminants) –Methane makes the second largest contribution to anthropogenic climate change after carbon dioxide –Meat production set to double by mid century –UK average consumption is 50g per day, which is more than the recommended amount “In Ireland reducing methane emissions produced by farmed animals by 20% is the equivalent of taking 25% of Ireland's cars off the road for a year” No point in reducing production in one country and replacing consumption with imports

Literature No study of vegetarianism using household data A few minor studies/polls carried out by vegetarian organisations -usually very small, unrepresentative samples Meat expenditure patterns and determinants of meat consumption have been studied in several countries using household expenditure data –Ireland by Newman et al (2001) –USA by Nayga (1995) –UK by Burton et al (1994) –Japan by Chern et al (2002) –Mexico by Gould et al (2002) This is the first paper to estimate the number of vegetarian households in multiple countries

Data and Methodology Living Standard Measurement Studies –Albania, Azerbaijan, Bosnia, Bulgaria, Kosovo, Serbia, Kyrgyzstan, Tajikistan, Brazil, Peru, Guatemala, India, South Africa, Tanzania, Ivory Coast, East Timor, China Household Income and Expenditure Data –Ireland, France, Nepal, Jamaica, USA, UK, Vietnam, Russia, Singapore, Australia, and Germany 120 observations (country-year) in total, from some 600,000 micro-data Consumption versus Expenditure Problems with recall and infrequency of purchase

Infrequency of purchase Only include households that have done a “full shop” foodshare i =(foodexp i /n i d )/(Income i t ) Find mean and standard deviation of foodshare for each income decile Omit from analysis if foodshare i <[avgshare j - (0.5*sdshare j )]

USA The US Consumer Expenditure Survey reports expenditures for 1 or 2 weeks Divides food purchases into 9 categories –cereal and bakery products, meat products, fish products, eggs, milk and dairy products, processed fruit or vegetables, fresh fruit or vegetables, sweets, non alcoholic beverages and miscellaneous food and oils Omitted from analyses if expenditure in 6/9 groups = 0 Remaining sample: >5,000 households per year Find % of households that report zero expenditure/consumption on meat products “At home” consumption only

Results: Per Capita Income

Latin America, Central Europe, Vietnam, Nepal East Timor, Ivory Coast, India, Eastern Europe

Results: Per Capita Income Russian Federation China, Africa

Results: Per Capita Income Australia USA

Per Capita Income: World

Meat Production IrelandUSA, France, Brazil, UK East Timor

Meat Production Central Europe, Latin America, Asia India, Peru, Eastern Europe

Results: Religion

Extensions Results above are for all-vegetarian households There are mixed households as well Methodology –Observe expenditure for one person households –Predict meat and non-meat expenditure for each household given its income –Derive probabilities of the share of meat in total food expenditure, conditional on the hypothesized number of vegetarians –Compare probability to observed meat-share

Vegetarians in Mixed households

Conclusions There are over 900 million vegetarians 94% of these are vegetarians of necessity The remaining 6% are vegetarians of choice In the medium term, the number of vegetarians will fall and methane emissions rise In the long term (and in the medium term in the OECD), rising vegetarianism will curb the growth in methane emissions

Per Capita Income: World