Agricultural mitigation

Following the last post on climate change mitigation within cities, I’m now going to switch to the opposite end of the spectrum and look at rural environments and agriculture.

The industry was responsible for 24% of anthropogenic GHG emissions between 2000 and 2010, placing it second only behind the energy sector. Contributions were largely from livestock, soil and nutrient emissions,and deforestation.

With such a significant proportion of emissions originating from agricultural practices, it is understandable that it has become an epicentre for emission reduction ideas. These range from individual ideas, most notably a simple reduction in the amount of meat consumed  to lower the demand, but research has also been completed into making agricultural practices more environmentally friendly.

Smith et al. (2007) estimated that the potential cut of emissions from agriculture totals as much as 6000 Mt CO₂-equivalent per year. After a bit of quick maths, this equates to the emissions of over 1.2 billion cars (based on the EPA stats for average emissions, and roughly equals the total number of cars on the road globally.

The paper by Smith et al. categorise mitigation strategies into three main principles:

1.       Reducing emissions: the most appropriate methods are location dependent but in a broad sense emissions can be controlled by managing the agricultural ecosystem more efficiently. An example would be using feeds for livestock that help to limit methane emissions.

2.       Enhancing removals: Better management of soils to either increase storage of carbon or slow the rate of release.

3.       Avoiding emissions: Predominantly achieved through the use of crops or residues for energy, helping to lower emissions despite still releasing carbon dioxide.

The study then goes into detail about specific mitigation strategies, broken into the following categories:

- Cropland management

- Grazing land management/pasture improvement

- Management of organic soils

- Restoration of degraded lands

- Livestock management

- Manure/biosolid management

- Bioenergy

Cropland management is probably the most encouraging of these, with none of the strategies shown to produce higher CO₂, CH₄ or N₂O emissions. Specifically, land-use change offers reduced emissions for all three gases with extensive evidence and agreement within the scientific community.

Finally, the paper produces data for the regions that have the highest mitigation potential (Figure 1). Southeast Asia and South America.

Figure 1: Mitigation potential calculated for each country. Southeast Asia and South America hold the most potential for emission reductions.
Source: Smith et al. (2007)

Potential vs reality

Something that is briefly mentioned but generally overlooked by the authors is the disparity between the mitigation potential and the quantity of mitigation that is actually realistic. Smith et al. (2005) studied the level of overestimation of carbon sequestration in European croplands. The paper looked at carbon sequestration data for a number of cropland management methods and the distribution of the different practices through a number of European countries, resulting in an estimate for the total carbon sequestration in each country.

A key finding was that the total cropland area being actively managed decreased in all countries between 1990 and 2000, and was likely to continue to decrease through to 2010. The authors found that carbon sequestration was negligible in most countries, and vastly different to the large estimates for mitigation potential produced by other studies. This gap is put down to economic, social and political barriers, and it is noted that little progress will be made without active backing and encouragement from policymakers.

Despite this, evidence does exist that agricultural emissions are decreasing. The OECD have found that there has been a reduction in emissions within its member countries (listed here) despite an increase production volume of 1.6% per year. It is worth noting, however, that the OECD is formed of developed countries and so is unlikely to be representative of the global picture.

Effect of climate change on agriculture 

There isn’t a one-way relationship between agriculture and climate change. As global temperatures rise and a more variable climate is experienced, the future for one of the most depended-upon sectors becomes increasingly uncertain. The effect on crop yields will be location-dependent, but significant areas are expected to see reductions (Figure 2).

Figure 2: The estimated changes in yield for maize, wheat and rice per country based on projections from the IPSL and Hadley models. Maize appears to be the most negatively impacted crop and is expected to suffer drastic reductions in yield.
Source: OECD

In Kenya, the farming sector is responsible for more than 25% of the GDP and over 75% of the population relies upon agriculture for some part of their earnings. The country’s National Climate Change Action Plan highlighted five key risks that are expected to hinder the sector:

- Less days for crop growth.

- Higher frequency of droughts.

- Reduced planning owing to more unpredictable climate.

- More frequent flooding of agricultural land.

- Increased pests.

These effects are clearly not exclusive to Kenya, and the strain on food production will only worsen as they occur. Climate-smart agriculture (CSA) is an approach championed by the FAO (a short summary video from Youtube is found below) which seeks to achieve locally-driven solutions in response to three key objectives:

- Increases in productivity and income.

- Climate change adaptation.

- GHG emission reductions.

By creating locally-focussed solutions that are aligned with some (or in some cases all) of the above, individual communities are given more help to tackle the detrimental effects climate change could have on their agriculture. The first point relating to increased income is particularly important because, as with the issues relating to carbon sequestration implementation, promotion from governments and authorities is essential.