The role of agriculture in global warming. How to measure GHG emissions from soils
Updated: Dec 12, 2022
Being involved in sustainable development means taking responsibility for what we do and how we do it. Have you ever thought that every member of our society contributes to global climate change? You may ask how – from heating our homes to filling up our cars, from burning fossil fuels and even to the food we eat– all these and many other human activities release the greenhouse gases (GHGs) that directly influence the increase of global temperatures.
Greenhouse gases are gases that trap heat in the atmosphere. During the day, the Earth’s surface is warmed by the sun rays. At night the surface cools, releasing heat back into the air. Due to the high percentage of gases in the atmosphere, though, some heat remains trapped. The gases that trap heat are called greenhouse gases. The increment of such gases in the atmosphere directly influences an increase of average temperatures.
Source picture : United States Environmental Protection Agency (EPA), 2022
In 2021, the carbon footprint reached 36,3 billion tons, the highest figure ever recorded.
The good news is that there is a way to avoid catastrophic climate change. According to the Net Zero Strategy, by 2050 the world must reduce emissions to a level as close to zero as possible. A small quantity of emissions will remain, but they will be absorbed thanks to natural ‘carbon sinks’, such as forests and oceans, and new carbon capture technology.
Another important international initiative is “4 per 1000” (4p1000), launched at COP 21 in 2015 and based on regeneration. It means that people should work on improving water, air, biodiversity, soils – the elements from which life on Earth originated for plants, animals, and humans. The actions within the “4 per 1000” Initiative include working on the regeneration of soils to improve their health, thanks especially to the carbon captured in the atmosphere by plants and returned to the soil in the form of organic plant matter or animal remains.
The “4p1000” Initiative means that increasing the ‘level of carbon stored by soils in the top 30 to 40 centimetres of soil […] by 0.4% (or 4‰) per year’ would ‘significantly reduce’ the increase of CO2 in the atmosphere (The international "4 per 1000" Initiative, 2022).
At present, agriculture is responsible for 10% of all greenhouse gas emissions in the UK. If we include emissions from land use change and deforestation, this indicator will account for 24% of GHG emissions globally.
The three main greenhouse gases (GHGs) emissions produced in agriculture are Nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2). Nitrous oxide comes largely from manure and fertiliser use. Methane is produced by livestock, via ‘ruminant enteric fermentation’. Methane is also produced from manure, but emissions differ depending on management techniques. Carbon emissions are associated with fuel and electricity use on farm, manufacture and production of feed and fertiliser, and how soils are cultivated.
Currently, the challenging task for farmers and developers is to possess or update their systems or tools to measure greenhouse gas emissions from soils, especially agricultural ones.
There are different ways to measure the GHG soil flux, ranging from direct measurements using samples of soils to flux measurement using soil chambers, spectral methods that rely on the reflectance of light on soil, remote sensing based on satellite imagery products. There are also various carbon calculator systems, such as Farm Carbon Toolkit, Cool Farm tool and soil carbon models – Yasso model, Century model, CBM-CFS3 model, C-TOOL model, etc.
We now need to find a solution that allows to conduct low-cost in-field measurements of greenhouse gas emissions from agricultural soils to be affordable for local farmers. Some organisations offer to allocate funding for such projects. Such initiatives show that the world is highly concerned with the current GHG emissions effects. It is no longer only a problem regarding big international organisations, but private companies and SMEs as well.
We all play our role in these global changes. The sooner we start paying attention to the way we live and conduct our business, the quicker we will find solutions to make our planet a safer place for future generations.