What are greenhouse gases?

1. What are greenhouse gases?

Greenhouse gases have been shown to be gaseous constituents capable of absorbing long-wavelength radiations reflected from the Earth's surface when illuminated by sunlight, and then dispersing the heat back to the Earth. , causing the greenhouse effect.

The main greenhouse gases include: water vapour, CO₂, CH, NO, O₃, CFCs. In the solar system, the atmospheres of Venus, Mars, and Titan also contain greenhouse gases. Greenhouse gases strongly affect the Earth's temperature, without them, the average surface temperature of the Earth would be about 33°C colder than it is today.

So the cause of the greenhouse effect is proven to be CO2. Because the greenhouse effect comes from the sun's radiation through the atmosphere reaching the ground. After absorbing radiation, the ground heats up and long wave radiation enters the atmosphere to be absorbed by CO2 causing the air temperature to rise.

The proven cause of the greenhouse effect is CO2.

Greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy in the thermal infrared range, causing the greenhouse effect as mentioned above. The main greenhouse gases in the Earth's atmosphere are water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). Without greenhouse gases, the average temperature of the Earth's surface would be about −18 °C (0 °F), instead of the current average of 15 °C (59 °F). The atmospheres of Venus, Mars, and Titan also contain greenhouse gases.

Human activities since the start of the Industrial Revolution (circa 1750) have increased the concentration of carbon dioxide in the atmosphere by almost 50%, from 280 ppm in 1750 to 419 ppm in 2021. The last concentration of carbon dioxide in the atmosphere was this high more than 3 million years ago. This increase has occurred despite the absorption of more than half of the emissions by the various natural carbon sinks in the carbon cycle.

At current rates of greenhouse gas emissions, temperatures could rise by 2°C (3.6°F), which the United Nations Intergovernmental Panel on Climate Change (IPCC) says is the upper limit to avoid 'danger' levels, by 2050. The majority of anthropogenic carbon dioxide emissions come from the burning of fossil fuels, mainly coal, petroleum (including oil) and gas natural burning, with additional contributions from deforestation and other changes in land use.

2. Sources of greenhouse gas emissions

Based on the origin, trend, absolute level as well as the degree of influence on the total potential of greenhouse gas emissions of countries, emission sources are divided into 4 main groups:

– Energy: As one of the largest sources of greenhouse gas emissions today. This sector typically contributes to over 90% of CO2 and 75% of other greenhouse gas emissions in developing countries. 95% of the gases from the energy industry are CO2, the rest are CH4 and NO with equivalent levels.

Emissions in the energy sector are divided into 3 groups:

• Emissions from burning fossil fuels (in the energy industries, transportation activities,.);
• Instantaneous emissions (i.e. the amount of gas and vapor discharged from the compression equipment due to leakage, unwanted or irregularity from the extraction, processing, transportation of fuel,.);
• Carbon capture and storage operations. In particular, emissions from burning fossil fuels contribute up to 70% of total emissions, typically from power plants and oil refineries.

– Industrial processes and product use (IPPU): Emissions from the IPPU sector arise in industrial process processes. The use of greenhouse gases in products and the use of carbon in fossil fuels is not intended for energy production. In particular, the main source of emissions is industrial processes that chemically or physically treat raw materials. Because in these processes, many types of greenhouse gases are generated, including: CO2, CH4, N2O, HFCs and PFCs.

– Agriculture, forestry and land use (AFOLU): The main sources of emissions include:

• CH4 and N2O emissions from livestock, wet rice cultivation, agricultural land, burning activities in agricultural production;
• CO2 emission/absorption in agriculture, forestry and land use change.

Collectively, the AFOLU sector contributes about 30% of global GHG emissions, mainly due to CO2 emissions from changes in land use (largely due to tropical deforestation) and CH4, N2O from farming and livestock farming.

- Waste:

• Greenhouse gases that can be generated in the waste sector include: CO2, CH4 and N2O.
• The main sources of generation recorded are: solid waste burial; biological treatment of solid waste; incineration and open burning of waste; wastewater treatment and discharge.

Normally, CH4 is emitted from solid waste landfills, accounting for the largest proportion of the total GHG volume of this sector. CH4 in wastewater discharge and treatment also plays a relatively important role. Besides, discharge and treatment of solid waste and wastewater also generate organic, volatile, non-methane compounds, NOx, CO and NH3. NOx is mainly produced when burning waste, while NH3 is generated during the composting process. These two compounds can indirectly generate N2O. However, the amount of N2O only accounts for a small, insignificant percentage.

The Kyoto Protocol is a protocol related to the United Nations Framework Convention on Climate Change at the international level of the United Nations with the goal of reducing greenhouse gas emissions specified 6 greenhouse gases. to be:

• Carbon dioxide (CO2);
• Methane (CH4);
• Nitrous oxide (N2O);
• Hydrofluorocarbons (HFCs);
• Perfluorocarbons (PFCs);
• Sulfur hexafluoride (SF6).

Substances that cause greenhouse gases.

On that basis, the Greenhouse Gas Protocol, jointly developed by the World Resources Institute and the World Business Council for Sustainable Development, has identified the sources of greenhouse gas emissions and divided them according to regions:

Zone 1: Direct Emissions

These are emissions directly from the activities of the agency/organization such as emissions due to fuel consumption in incinerators, chimneys or the use of vehicles and equipment owned by that agency/organization.

Zone 2: Indirect emissions

Is the type of emission of the agency/organization from the use of electricity purchased from electricity suppliers. This type of emissions is generated where electricity is produced.

Zone 3: Indirect emissions

All other types of indirect emissions of the agency/organization as a result of the activities of that agency/organization such as: use of purchased materials, use of public transport …

Data on sources of greenhouse gas emissions by years of emission groups are as follows:

Agriculture:

According to the results of the GHG inventory of the Ministry of Natural Resources and Environment, the amount of greenhouse gas emitted in the agricultural sector is 52.45 million tons of CO2, accounting for 50.5% of the total greenhouse gas emissions of the country. By 2013, the amount of greenhouse gas emissions in this field was 89.4 million tons of CO2, accounting for 34.5% of the total greenhouse gas emissions of the country.

The emission sources are divided into 4 main groups.

Land use, land use change and forestry:

According to the Practical Guide in the field of land use, it can be seen that based on statistics, land in the territory of Vietnam is classified into 6 types, including: forest land, cropland, grassland, wetland, residential land and other soils.

For the emission or absorption of greenhouse gases in the land use sector is the process of changing the carbon stock in:

• Aboveground and below ground biomass;
• Organic waste (dead trees, fallen leaves)
• Soil.

Waste

According to analysis in Vietnam, in recent years, each year, over 15 million tons of solid waste are discharged from different sources, of which over 80% are from urban areas. However, only over 70% of solid waste in urban areas and about 20% in rural areas is collected and treated.

While the sector's greenhouse gas emissions mainly include:

• CH4 emissions from solid waste landfills are collected; from industrial wastewater and domestic wastewater;
• N2O emission from domestic sewage sludge; CO2 and N2O emissions from waste incineration.

From the above bases, it can be seen that Vietnam is one of the countries with a continuous increase in greenhouse gas emissions, from more than 21 million tons to 150 million tons of CO2 in the 1990s to 2000 and gives a It is estimated that CO2 emissions will increase to 300 million tons by 2020.

As such, GHG emissions are statistically defined as the effects of energy emitted, effects of carbon emissions from energy, from the agricultural sector, land use change and forestry and also in the quality of life. discharged into the environment. Each of the emission groups accounts for the carbon weight, causing an equivalent effect in different proportions.