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Environmental Impact

There are 1.8 million dairy cows in the UK. Most of them give birth to a calf each year and they all have to be fed and the farms need to be maintained using electricity, fuel and vast amounts of water. Dairy farming also means endless battles with slurry and continuous emissions of methane (one of the main greenhouse gases) resulting from cows’ digestion.

When it comes to milk itself, the chain beginning with the milking of the cows, storing and processing their milk and ending with a customer taking the finished product home, eats up large amounts of energy and fuel and is responsible for even more emissions of greenhouse gases.

Carbon footprint refers to the emission of three major greenhouse gases produced in agriculture. These are carbon dioxide (CO₂), methane (CH₄) – produced in one of the cow’s stomachs as a result of food fermentation and from stored manures - and nitrous oxide (N₂O) produced as a result of soil management and the application of fertiliser and manure. Methane is 23 times more potent as a greenhouse gas than carbon dioxide, while nitrous oxide is almost 300 times as potent (DairyCo, 2012) and these conversions are usually reflected as ‘CO₂ equivalents’(see below).

The total carbon footprint of the UK dairy sector, including emissions from dairy farms, transport, distribution, processing and end use, is estimated to be 15.5 million tonnes of CO₂  per year (Carbon Trust, 2011).  

Just for comparison, if you drive to and from work every working day for an average of 40km (25 miles) a day, your car’s yearly emissions of CO₂ will be around 1.35 tonnes.

The UK agriculture sector as a whole is responsible for about 46 million tonnes CO₂  every year. However, emissions of nitrous oxide (51 per cent) and methane (38 per cent) – both significantly more harmful than CO₂ - dominate this sector (DECC, 2014).

Aspects of milk production

When assessing environmental impacts of dairy products we need to take the following into consideration:

  • production of farm inputs – crops (often imported from the Americas), fertilisers, pesticides, feed, bedding, tools, machinery, import of crops (soya, maize) and feed, water
  • dairy farming itself – breeding of cows and their daily life, maintenance, manure/slurry management, silage, pasture maintenance, milking parlour
  • transport to and from  the dairy
  • milk processing – see details here
  • dairy product packaging
  • dairy product transport to the retail distributor
  • dairy product retailing and transport to the consumer
  • dairy product utilisation – cooking, baking, heating, etc.

The dairy industry is also notorious for causing three to five times as many serious water pollution incidents as the beef sector (the vast majority relate to slurry and silage liquor) (Foster et al., 2007).

Here are a few examples of the energy and water requirements and greenhouse potential of some dairy-related foods (CO2 eq has got methane and nitrous oxide factored in as CO2 equivalents):

Food

Energy required (kJ/kg)

Emissions (kgCO2eq/kg)

Water (l/kg)

Milk

2,670-3,000

1.04-2.8

1,020

Cheese

n/a

8.8-26

5,060

Butter

17,800-21,300

n/a

5,553

Beef (including veal from dairy farming)

44,000

16

15,415

Eggs (figures per 20 eggs)

20,000

5.5

3,265

 

 

 

 

 

 

 

(AgriAssist, 2011; DairyCo, 2012; Foster et al., 2007; Mekonnen and Hoekstra, 2012)

 

How about plant-based foods?

According to Defra (Foster et al, 2006), cereal, bread, flour and related products account for a little over one per cent of the EU’s global warming potential and fruit and vegetables (including frozen ones) account for approximately two per cent.

Here are a few examples:

Food

Energy required (kJ/kg)

Emissions (kgCO2eq/kg)

Water (l/kg)

Bread

11,700

0.908

1,608

Potatoes

1,300

0.215

287

Rice

9,800

6.4

1,673

Apples

400-900

0.04-0.1

822

Carrots

n/a

0.67

195

Tomatoes

1,500-5,000 (unheated systems)

3.3-9.4

214

Bread wheat

2,000

0.8

1,827

(Foster et al, 2006; Mekonnen and Hoekstra, 2011)

In contrast with 1,020 litres of water needed to produce one litre of milk, the total of 297 litres of water are used to produce one litre of soya milk (Ercin et al., 2012).

 

 

 


 

For more information about animal farming and the environment, see our Hot Campaign.

 

References: 

Agri Assist, 2011. UK Dairy Industry Carbon Footprint. Morrissons Farming.
Carbon Trust, 2011. Industrial Energy Efficiency Accelerator. Guide to the Dairy Sector CTG033. Carbon Trust, London.
DairyCo, 2012. Greenhouse gas emissions on British dairy farms DairyCo carbon footprinting study: Year one. AHDB, Kenilworth.
Department of Energy and Climate Change (DECC), 2014. 2013 UK Greenhouse Gas Emissions, Provisional Figures and 2012 UK Greenhouse Gas Emissions, Final Figures by Fuel Type and End-User
Ercin, A.E., Aldaya, M.M. and Hoekstra, A.Y., 2012. The water footprint of soy milk and soy burger and equivalent animal products. Ecological Indicators. 18: 392 – 402.
Foster, C. et al., 2006. Environmental Impacts of Food Production and Consumption: A report to the Environment, Food and Rural Affairs. Manchester Business School. Defra, London.
Foster, C. et al., 2007. The Environmental, Social and Economic Impacts Associated with Liquid Milk Consumption in the UK and its Production. A Review of Literature and Evidence. Department for Environment, Food and Rural Affairs, London.
Mekonnen, M. M. and Hoekstra, A. Y., 2011. The green, blue and grey water footprint of crops and derived crop products, Hydrology and Earth System Sciences.15, 1577-1600.
Mekonnen, M. M. and Hoekstra, A. Y., 2012. A Global Assessment of the Water Footprint of Farm Animal Products. Ecosystems. 15: 401–415.

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