How agriculture affects Southeast Asia’s air
Greenhouse gases (GHG) absorb infrared radiation, trap heat in the atmosphere and cause an increase in temperature. Ultimately, GHG leads to global warming. The primary GHG are water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and ozone (O3). In this article, we will focus on the emissions of GHG from the agricultural sector.
First, we present an overview of the total emissions of GHG from the agricultural sector of Southeast Asian countries. The main GHG in the data are nitrous oxide and methane. The data contains all the emissions produced in the different agricultural sub-domains which includes enteric fermentation, manure management, rice cultivation, synthetic fertilizers, manure applied to soils, manure left on pastures, crop residues, cultivation of organic soils, burning of crop residues and burning of the savanna. Based on the graph, we can see that Indonesia leads in the total emissions of GHG and its difference with other countries in the region has been growing since 1989. Besides, the GHG emissions of Thailand, Myanmar, Viet Nam and the Philippines are in a similar range around 2000 to 2500 gigagrams. Emissions of Cambodia, Malaysia, Lao PDR, Singapore, Timor-Leste and Brunei Darussalam are in the lowest range, below 700 gigagrams.
Next, we will look at the GHG emissions of crops growing domains in the agriculture sector, which are rice cultivation, synthetic fertilizers, crop residues and burning of crop residues. In the rice cultivation sub-domain, methane gas is emitted from the anaerobic decomposition of organic matter in paddy fields. The graph showed that, as of 2018, Indonesia had the greatest methane gas emissions from this sub-domain, followed by Thailand and the Philippines. Overall, the ranking of Southeast Asian countries in terms of emissions from rice cultivation is similar to their ranking of emissions from the whole agricultural sector.
In the synthetic fertilizers sub-domain, the GHG emitted is nitrous oxide. The emissions of nitrous oxide can be classified into direct emissions and indirect emissions. The former is produced by microbial processes of nitrification and denitrification, while the latter is produced from re-deposition and leaching processes. In this sub-domain, as of 2018, the leading country was Indonesia, followed by Viet Nam, Thailand, the Philippines and Malaysia. Besides, the upward trend in these emissions only took off in 1971, implying that synthetic fertilizers (Nutrient Nitrogen) were not common in the region before 1971.
Also, nitrous oxide gas is emitted from crop residues, mainly due to the nitrogen (N) in the residues. From the graphs, Indonesia is still the leading country and it has maintained its leading position for 60 years. Notably, the gap in GHG emissions between Indonesia and other countries has been widening since 1979.
The burning of crop residues emits methane gas and nitrous oxide gas. The burning of crop residues is a common way of managing crop residues. It is useful for producing energy using unused biomass resources. However, the burning of crop residues emits methane gas and nitrous oxide gas that contribute to air pollution. In Southeast Asia, the country with the highest GHG emissions from burning crop residues is Indonesia, followed by Thailand, Viet Nam, the Philippines and Myanmar.
We have looked into the GHG emissions of crops growing domains in the agriculture sector in terms of their absolute value. Now, we are going to discuss the emissions in terms of value per capita as it is more persuasive in comparison. First, we look into the total emissions of GHG from the agricultural sector of Southeast Asian countries. There is generally a downward trend and this may due to the rise of environmental awareness. However, some countries, such as Cambodia, Lao PDR and Timor-Leste, have a more fluctuated emission trend.
In the rice cultivation sub-domain, as of 2018, Cambodia had the greatest per capita methane gas emissions, followed by Thailand and Myanmar. Interestingly, we noticed that Cambodia has always been at the top over the 60 years, except for 1970 to 1980. Although its per capita emissions in 2018 fell by almost half of its value in 1961, this improvement was probably due to the increase of population as its absolute value of emissions does not change much. On the other hand, the per capita methane gas emissions of Indonesia, Malaysia, Timor-Leste and Brunei Darussalam from this sub-domain do not change much and have stayed at a certain level for around 60 years. Also, the Philippines had the second greatest per capita methane gas emissions in 1961 (about 39 kilograms per capita) dropped its position to the fourth greatest in 2018 (about 15 kilograms per capita). This might due to the effort that the Philippines had put in reducing the emissions as the absolute value was increasing but the population growth was even slower than the population growth of Cambodia.
Next, we look into the synthetic fertilizers sub-domain. The trend of each countries’ per capita nitrous oxide gas emissions is similar to their absolute value trend. The top three countries which have the greatest per capita nitrous oxide gas emissions are Thailand, Vietnam and Malaysia. We also noticed that Malaysia almost had the greatest per capita emission from 1961 to 2012 although its absolute value of emissions is not the greatest. This actually exposed that Malaysia had a problem with excessive GHG emissions in this sub-domain during that period of time. Fortunately, the problem seemed to be being addressed as there was a downward trend since 2012. Besides, although Indonesia’s nitrous oxide gas emissions were far greatest than the other countries, its per capita emissions were not that great. It had the fourth greatest per capita emissions and its emissions growth rate was reasonable.
In the crop residues sub-domain, we can see that almost all Southeast Asian countries had an upward trend in per capita nitrous oxide gas emissions from crop residues, especially from the 1970s onwards. The top five countries in this sub-domain were Cambodia, Lao PDR, Myanmar, Thailand and Vietnam as of 2018. Among these countries, Cambodia and Lao PDR, which had relatively fewer emissions in terms of absolute value, had relative great per capita emissions and this phenomenon should be paid close attention to. Also, the emissions of these two countries were more fluctuated than the other countries, showing that the countries might lack stable gas emission treatment policies and this might be a good point to dive in deeper.
Lastly, when we looked into the burning of crop residues sub-domain, we noticed a downward trend for both nitrous oxide and methane gas emissions. This might because people were becoming more aware of the damage that burning crop residues do to the environment as well as the air and efforts had been made to address the problem. It is believed that crop residues must have increased with the growth of the population. However, GHG emissions from the burning of crop residues, which is the most common way of managing crop residues, decrease gradually. This is a pleasant phenomenon showing that environmental awareness has been raised over the years and there may be another means of managing crop residues.
