How Australia accounts for agricultural greenhouse gas emissions

Page last updated: Friday, 13 April 2018 - 1:57pm

As a signatory to the United Nations Framework Convention on Climate Change, the Australian Government conducts an annual inventory of the nation's sources and sinks of greenhouse gases. The 2015 inventory shows agriculture was responsible for about 16% of Australia’s greenhouse gas emissions in 2013.

The Department of Primary Industries and Regional Development (DPIRD) works with people in Western Australian agriculture to manage the economic, environmental and social impacts of climate change.

Agriculture is an important source of greenhouse gas emissions

Agriculture was responsible for about 16% of Australia’s greenhouse gas emissions in 2013, and the sources (see Table 1) are:

  • 66.3% from enteric fermentation in ruminant livestock (eructation and flatulence)
  • 15.5% from agricultural soils
  • 10.8% from prescribed burning of savannas
  • 3.9% from manure management
  • 2.4% from liming and urea application
  • and the remainder from rice cultivation and field burning of agricultural residues.

Livestock and the manure they create were the dominant source of methane, accounting for 52% of total national methane emissions, and agricultural soils were the dominant source of nitrous oxide, accounting for 62% of total national nitrous oxide emissions.

Not all greenhouse gases are equal

The global warming potential of methane is 25 times that of carbon dioxide, and nitrous oxide is 298 times that of carbon dioxide. This means that 1 tonne of methane is equivalent to 25 tonnes of carbon dioxide; 1 tonne of nitrous oxide is equivalent to 298 tonnes of carbon dioxide.

Each greenhouse gas has a unique residence time in the atmosphere and unique heat-trapping potential. The concept of global warming potential is used to express these unique values relative to carbon dioxide over a specified period. Under the United Nations Framework Convention on Climate Change, the global warming potential of greenhouse gases is expressed in terms of how much carbon dioxide would be required to produce a similar warming effect over 100 years. This is termed the carbon dioxide equivalent value (CO2-e).

Some emissions are not counted as agricultural emissions

Under current accounting rules, emissions generated during the manufacture and transport of agricultural inputs — such as fertilisers, herbicides, pesticides and agricultural machinery — are not counted as agricultural emissions. Emissions from the fuel used by agricultural vehicles either on-farm or in transporting produce and the fuel used to generate electricity consumed on farm is also excluded.

Table 1 Greenhouse gas emissions from Australian agriculture in 2013, expressed as megatonnes of carbon dioxide equivalent (CO2-eMt)

Greenhouse gas source

Carbon dioxide

(CO2-eMt)

Methane

(CO2-eMt)

Nitrous oxide

(CO2-eMt)

Total

(CO2-eMt)

Percentage of agricultural emissions (% rounded)

Enteric fermentation

-

56.38

-

56.38

66.3

Manure management

-

2.42

0.89

3.31

3.9

Rice cultivation

-

0.56

-

0.56

0.7

Agricultural soils

- -

13.16

13.16

15.5

Prescribed burning of savanna

-

6.87

2.33

9.20

10.8

Field burning of agricultural residues

-

0.24

0.15

0.39

0.5

Liming

0.76

- -

0.76

0.9

Urea application

1.28

- -

1.28

1.5
Agriculture total 2.04 66.46 16.53 85.03  

Contact information

Rob Sudmeyer
+61 (0)8 9083 1129