If New Zealand is to achieve zero net greenhouse gas emissions by 2050, we will all need to cut these emissions in our daily lives. That means changing our lifestyles to low greenhouse gas alternatives. We know about the greenhouse gas emissions from burning fossil fuel – the principal contributor to global warming worldwide. But there are also substantial emissions associated with many of the foods we eat. And, unfortunately, the highest emissions are associated with some Kiwi favourites – beef, lamb and venison.
Ruminants, the group of animals including cattle, sheep, goats and deer, have chambered stomachs which allow them, with the help of bacteria, to digest the cellulose fibre in grass and hay. Unfortunately, some of these bacteria also generate methane gas, a potent greenhouse gas, which gets released to the atmosphere. In addition, pasture fertiliser and cattle urine are rich in nitrates, part of which are converted by soil bacteria to nitrous oxide gas, another potent greenhouse gas. Methane and nitrous oxide emissions are largely responsible for pushing red meat up in the emissions ranking.
According to a 2011 report by Environmental Working Group, a US non-profit advocating for consumer product safety and sustainability, a kilogram of consumed beef – the beef we actually eat - produces the equivalent of 27 kilograms of CO2 from burned fossil fuels. The shorthand for this is 27 kg of “CO2e” (carbon dioxide equivalents), to account for greenhouse gases other than CO2. So what does 27 kg mean in this context? For comparison, a kilogram of consumed beef creates about the same amount of greenhouse gas as a drive from Blenheim to Nelson and back in a standard petrol passenger car.
Keep in mind that the value for New Zealand beef, which is mostly grass-fed, may be different than that for US beef, which is largely grain-fed. But while there are emissions associated with feed grain, that are not associated with grass-fed beef, these emissions could be more than offset by the slower growth rate of our grass-fed beef (meaning more lifetime emissions), so the exact difference is unclear. The other important point about this ‘emissions value’ of 27kg is that it includes production, transportation, processing, cooking and waste!
Lamb is even higher, at 39 kg CO2e per kg of meat consumed, largely because less of the animal is used for food. Pork, chicken and eggs produce less of these emissions, at 12.1, 6.9 and 4.8 kg CO2e per kg, respectively, and may be better meat choices for the climate-conscious consumer.
So, if cattle produce so much greenhouse gas, what about dairy products which come from cattle? Cheese tops the scale of non-meat foods, with 13.5 kg CO2e per kg consumed; more than pork. The emissions associated with air freighted imported cheese are about 46% higher, so it is far better to eat New Zealand cheese. By comparison, yogurt and tofu each produce about 2 kg CO2e per kg consumed (as long as they are not being flown into the country!).
Milk is relatively low, at 1.9 kg CO2e per kg consumed, but Kiwi consumers tend to drink quite a bit of it, so the emissions add up. The emissions from milk substitutes, such as soy, pea or almond milk, are quoted from a number of sources and are around 0.4 kg CO2e per kg. The value for milk substitute actually consumed will be slightly more, to include waste and transport, but will still be about a quarter of that of cow’s milk.
The emissions associated with fresh vegetables are relatively low; for example, 2.0 kg CO2e per kg consumed for broccoli and 1.1 for fresh tomatoes. Interestingly, about a quarter of the emissions associated with these fresh vegetables is due to waste and another quarter due to transport. This shows the importance of buying locally grown produce in keeping emissions low. Air freighting fruit and vegetables from California generates another 1.2 kg CO2e per kg. Sea freighting that same distance generates only an additional 0.2 kg CO2e per kg.
Grains and beans have relatively low emissions. Rice ranks highest at 2.9 kg CO2e per kg consumed due to methane produced in waterlogged rice paddies. Lentils rank lowest with 0.9 kg CO2e per kg consumed, half of which is due to the energy needed to cook them.
Learning about these values has certainly changed my eating habits and, hopefully, these values will also have you thinking about how to reduce your household’s emissions. Food for thought, if nothing else!
The posts are a collection of opinion articles written by CKM member Tom Powell for the Marlborough Express. Tom is a retired geologist who came to New Zealand in 2004 to work in the geothermal industry on the North Island, is a New Zealand citizen and now lives in Blenheim.