Farming and greenhouse gases
Earth's climate has always warmed and cooled over time and will continue to do so. The speed and extent to which it does depend on both natural processes and human activities.
The greenhouse effect
Greenhouse gases occur within our atmosphere; they allow energy from the sun to pass through to the Earth's surface but prevent some of the energy escaping. Although greenhouse gases are minor components of the atmosphere, Earth would be much colder without them. The average temperature would drop from 15 degrees Celsius down to about minus 18 degrees Celsius, making Earth unsuitable for life.
Since the Industrial Revolution, human activities, like the burning of fossil fuels and deforestation, have increased the concentration of these gases in the atmosphere. As a result, more energy is "trapped" which enhances the greenhouse effect leading to changes in the Earth's energy balance and temperatures.
Rising temperatures affect global weather patterns – potentially causing increased frequency and severity of:
- unusually warm and unusually cold seasons.
Changes to temperatures and soil moisture levels also affect how, when and where plants grow.
Carbon dioxide, methane and nitrous oxide
Some of the major greenhouse gases are carbon dioxide, methane and nitrous oxide.
Carbon dioxide is produced in the extraction, production and use of fossil fuels – such as petrol and coal.
Methane is produced by ruminant animals (animals that have 4 parts to their stomach). Cows, sheep, goats and deer are all ruminants.
Forage eaten by ruminants is digested by microbes in one part of a ruminant's stomach – known as the rumen. A by-product of the digestion process is methane which is expelled on a regular basis from the rumen through the mouth, a process called eructation.
Nitrous oxide gas commonly comes from the conversions in the soil by microbes of nitrogen in fertiliser, urine and dung. Nitrogen fertiliser is used to increase plant production in both dairy and crop farming. The amount of nitrogen fertiliser used in New Zealand has increased substantially over the past 30 years, particularly as a result of the increase in dairy production.
All forms of animal waste produce both methane and nitrous oxide gases.
Improving our processes
MPI funds and leads a wide variety of research programmes which aim to increase our understanding of greenhouse gas generation and processes for mitigating it.
Reducing greenhouse gas emissions on farms
Our farmers are among the most productive and efficient in the world. Over the past 20 years, they have improved the emissions efficiency of production by about 1% a year. They have done this by improving:
- feed and nutrition
- animal genetics
- pasture management
- animal health.
Although total agricultural emissions have grown by 15% since 1990, they would have increased by more than 40% if it wasn’t for the efforts of our farmers.
More can be done
Farmers can continue to improve their emissions efficiency through a number of means, including:
- establishing new forests to off-set emissions – known as creating "carbon sinks"
- using fertiliser more efficiently.
Options that reduce biological emissions without reducing the number of animals on farms are still fairly limited and MPI is committed to finding ways to expand them. Both the government and the sector have established research and development programmes dedicated to this aim.
Research and development continues
Every year, we invest around $20 million in the research and development of ways to reduce biological emissions from agriculture – such as the New Zealand Agricultural Greenhouse Gas Research Centre. And it's paying off.
In early-2015, our scientists announced they'd identified animal-safe compounds that can significantly reduce methane emissions from sheep and cattle. Later that year, they showed that global solutions to reduce methane emissions from ruminant animals are feasible because the rumen microbes causing emissions are similar globally.
These discoveries are big steps in the right direction. However, much more work is required before we can turn these scientists' discoveries into safe and reliable on-farm options.
Find out more
- Find out how MPI administers the ETS in the forestry sector
- Learn about the Permanent Forest Sink Initiative
- Read about New Zealand's role in the Global Research Alliance for Agricultural Greenhouse Gas Emissions
- Visit the New Zealand Agricultural Greenhouse Gas Research Centre website
- Check out the Pastoral Greenhouse Gas Research Consortium
- View an interactive timeline of the history of the Emissions Trading Scheme in New Zealand – Motu website
Who to contact
If you have questions about farming and the ETS, email firstname.lastname@example.org.