Greenhouse Gases

Greenhouse Gases

Greenhouse gases let sunlight pass through the atmosphere, but they prevent the heat that the sunlight brings from leaving the atmosphere. The main greenhouse gases are:

  • Water vapor - H2O
  • Carbon dioxide - CO2
  • Methane - CH4
  • Ozone - O3
  • Nitrous oxide - N2O
  • Chlorofluorocarbons
  • Fluorocarbons
  • Sulfur hexafluoride - SF6

These greenhouse gases trap the sun’s energy in the atmosphere. Greenhouse gases occur naturally as well through human activity. The more greenhouse gases there are, the more of the sun’s energy is trapped and the greater the rate of change.

According to the CSIRO, greenhouse gases create the greenhouse effect - a natural atmospheric process that keeps the Earth's surface at a temperature comfortable for humans and other life to exist. The natural greenhouse effect keeps the surface of our planet at a habitable temperature, about 33°C higher than it would be without an atmosphere.

Approximately 48% of the Sun's incoming energy reaches the surface of earth and warms the ground. This warmed ground then emits heat as infrared radiation. A lot of the infrared radiation is trapped in the air by the greenhouse gases, which radiate heat back to the ground.

The natural greenhouse effect has been enhanced over the past two centuries by an increase in activities such as:

  • the burning of fossil fuels for energy and transport
  • expanding agriculture and deforestation.

These activities have led global atmospheric concentrations of carbon dioxide and other greenhouse gases to increase from 277 ppm in 1750 to 412 ppm in 2020. This increase in greenhouse gas emissions is causing global warming.

The Intergovernmental Panel on Climate Change, the world's leading body for assessing climate change, reports that human influence on the climate system is clear.

Greenhouse Gas Emissions by Sector

Greenhouse Gases

The above graph demonstrates the contribution of each sector to total net greenhouse gas emissions for South Australia in the 2019 financial year. Agriculture is the second highest emitter. The Limestone Coast is a significant primary production region and contributes to 20% of the state’s agriculture income.

Source: Department for Environment and Water - Climate Smart South Australia

"Agricultural production contributed 24% of South Australia's greenhouse gas emissions in the 2018 financial year, with the major sources of emissions stemming from cattle, sheep and agricultural soils".

‐ Government of South Australia - South Australian Government: Climate Change Action Plan 2021 - 2025

Agricultural Greenhouse Gas Emissions Profile

Greenhouse Gases

The above pie chart demonstrates Agriculture was responsible for about 13.5% of Australia’s greenhouse gas emissions in 2018. Livestock and the manure they create were the dominant source of methane, accounting for 46% of total national methane emissions, and agricultural soils were the dominant source of nitrous oxide, accounting for 57% of total national nitrous oxide emissions.

Source: Department of Primary Industries and Regional Development, Western Australia.