Science & Technology in Action

10th Edition

Agriculture and Climate Change

Department of Agriculture, Food and the Marine

Agricultural Science
Agriculture’s most significant contributions to global greenhouse gases are due to methane (8.6%) and nitrous oxide (5.5%). In fact agriculture is the most significant source of these gases. While agriculture itself contributes relatively little to CO2 levels, changes in land use make a much greater contribution (12%).
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Lesson excerpt

Climate change is a natural phenomenon. Human history has recorded hot episodes, mini ice ages and temporary changes caused by volcanic eruptions. A catastrophic climate change, resulting from a meteorite impact, wiped out the dinosaurs. 

On Earth, life as we know it is maintained by greenhouse gases in the atmosphere (mainly water and carbon dioxide) – they retain some of the energy radiated from the Earth’s surface towards space. Without them the average temperature on Earth would be −18°C and there would be extreme temperature differences between day and night, as happens on the Moon. 

In the past 200 years the increased industrialisation, mechanised transport and agriculture, urbanisation and increasing human population have raised the level of atmospheric carbon dioxide from about 280 ppm to about 390 ppm, enhancing the greenhouse effect and raising global temperatures. Over the same period atmospheric methane (CH4) has risen from 720 ppb to 1800 ppb; its global warming potential is 25 times that of CO2 over a period of 100 years. Anthropogenic global warming has led to warmer weather, reduced ice cover, desertification and more frequent extreme weather events. 

Climate change has consequences for agriculture. In many places glacial melting causes flooding and, later, drought. Global production of maize, wheat, rice and meat has been affected by storm damage, drought and flooding. Poultry have suffered from heat stress. Moreover, farm organism-parasite relationships can change in unpredictable ways. 

Agriculture can respond in a number of ways. Better water storage facilities reduce the risk of drought. Hardy seed varieties or animal species — less used because of lower productivity — can be used again. Climate change has shortened growing seasons in the tropics but extended them in places like Ireland and New Zealand. Formerly frozen Arctic land may now become productive. 

The regions most severely affected by climate change are often the poorest. It is clear that global cooperation is required to ensure sharing of economic resources, technology, knowledge and training. 

The urgent need to limit the growth in greenhouse gas emissions poses a major challenge for agriculture. Worldwide, there is substantial malnutrition and a growing population. The demand for meat and dairy products is on the rise. At the same time, this agriculture sector is expected to reduce emissions, particularly of methane (CH4) and nitrous oxide (N2O) – two powerful greenhouse gases. 

True or False?

  1. Farmers can reduce GHG emissions by keeping machinery in good working order and carefully planning field operations. true
  2. Production of fertilisers, feed and animal medicine involves GHG emissions. true
  3. A slight increase of 2 degrees in average global temperatures is no cause for concern. false
  4. Planting trees with deeper roots in order to reduce storm losses has an adverse effect on carbon sequestration. false
  5. ‘Radiative forcing’ is a phenomenon of no significance to climate change. false
  6. Elevated CO2 levels are affecting ocean ecology. true
  7. The effects of GHGs have reached saturation level. Further emissions will not affect Earth’s climate. false
  8. Although burning increases GHG emissions, it can have beneficial effects on soil and ecosystems. true