Agriculture and greenhouse effect

Agriculture is both one of the sectors most vulnerable to the impacts of climate change and a net contributor to anthropogenic emissions of greenhouse gases. With 15% of global emissions, agriculture rejects methane from livestock and land, nitrous oxide from fertilization with nitrogen and manure management and carbon dioxide from energy consumption.

The impact of agriculture

According to its impact on agricultural lands and practices, agriculture can also be used to capture CO2 from the atmosphere and thus mitigate climate change, but it can also contribute to global warming, for example by causing deforestation.

If emissions from agricultural sources are declining in most industrialized countries, the globalization of trade and population growth partly explain the sharp increase in agricultural emissions in developing countries.

Similarly, if methane (livestock, waste management and rice cultivation) is the main gas emitted in the South, it is nitrous oxide (use of fertilizers and manure management) which tops agricultural emissions in the North.

However, it is important to note that due to the complexity and variability of agricultural systems, uncertainties remain regarding the assessment of these emissions, necessitating a research effort in this area.

All agriculture production except the ones for organic cultivation use fertilizers and synthetic pesticides, which must be produced, and this requires fossil fuels, thus generates CO2 emissions (synthetic fertilizers are produced from natural gas). So when you eat carrots or apples, or when you drink coffee or orange juice, remember that this contributes to the global warning effect. Not just driving your car.

If we reason to the hectare, synthetic fertilizers are mainly upstream emissions, pesticides are much more marginal emissions for greenhouse gas emissions. Moreover, intermediate chemical reactions in the fertilizer production also generate some N2O.

Economics behind it

Of course the emissions associated with the manufacture of these products are not counted under agriculture, but under “industry”. Expenditure for the purchase of raw products such as vegetables or fresh fruit in bulk, or fresh meat, represent only about 20% of all of what we spend on food on average.

The rest of our spending is devoted to production of processed food like pasta, canned and frozen foods, ready meals, biscuits and sweets, drinks,… These industries consume energy directly, and therefore emit greenhouse gases as well that will be included in the products we buy, with about 15% of the energy industry in developed countries made by the food industry. Next these products are usually packed.

It turns out that the manufacture of packaging represents a significant fraction of base material that we produce such as aluminum and plastics. Basic materials production is responsible for 70% to 80% of emissions from the industry, with a part of the package that will be used at the supermarket.

Solutions exist to reduce emissions of greenhouse gases in agriculture: optimizing of the use of nitrogen fertilizers, better waste management to producing energy from waste, development of simplified cultivation techniques but also in some cases deployment of energy efficiency and use of renewable energy.

The future of agriculture

Today it is not possible to make a precise comparison between farming systems (organic, rational, conventional) from the standpoint of only gas emissions. This is partly due to many uncertainties, but also to the lack of accurate data on the full gas balance of different systems, both because of their their diversity and complexity.

However, it is clear that agriculture in the 21st century will have to answer a series of environmental, social and economic challenges involving a fundamental change in practice, notably to meet the need of mitigation of gas emissions and the preservation and ecosystem restoration.

The international community is committed to maintain global warming to below a 2 degrees Celcius increase. This implies a division by at least 2 of global emissions by 2050 and a reduction by a factor of 4-5 in the industrialized countries. In this sense Europe has committed to at least a 20% reduction of greenhouse gas emissions by 2020. These objectives defined at the international level require the mobilization of all sectors, including agriculture, which will have to undergo a profound change to meet the climate challenge.

The adaptation of agriculture and forestry systems to this new climate situation as well as the effects on diseases, pests and weeds require new skills in agronomic and forestry: development of new varieties, development of cultivation techniques adapted or forestry, etc. This adaptation also leads us to consider the geographic mobility of production areas.

Migration of cropping or forest species to enhance adaptation, new agroclimatic potential and forestry, biotech opportunities in connection with the economic determinants, and more generally the future direction of the duties of the agricultural and forestry production.