Greenhouse Gas and Carbon Emissions
Greenhouse gases are gases in the atmosphere that absorb solar radiation reflected from the ground and re-emit it. Greenhouse gases in the 2006 Guidelines for National Greenhouse Gas Emission Inventories include carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, nitrogen trifluoride, halogenated ethers, etc. All of these gases have the ability to absorb infrared light, which can produce a “greenhouse effect”, which can bring catastrophic consequences such as sea level rise and extreme weather.
Water vapor, carbon dioxide, nitrous oxide, methane, and ozone are all major greenhouse gases in the Earth’s atmosphere. Among them, the greenhouse effect produced by water vapor accounts for 60%-70% of the overall greenhouse effect, followed by carbon dioxide (about 26%), and finally ozone. However, due to the large changes in the temporal and spatial distribution of water vapor and ozone, the formulation of emission reduction measures generally does not take them into account, so carbon dioxide has become the greenhouse gas with the largest proportion and the most significant impact, so the emission reduction is mainly aimed at carbon dioxide. In order to facilitate the understanding of the public, carbon dioxide emissions are often referred to as carbon emissions.
Carbon source and carbon sink
The United Nations Framework Convention on Climate Change (UNFCCC) defines a carbon source as a process, activity or mechanism that releases carbon dioxide into the atmosphere, and a carbon sink as a process, activity or mechanism that removes carbon dioxide from the atmosphere. This shows that carbon source and carbon sink are two relative concepts.
The energy sector produces a large amount of carbon dioxide emissions through the combustion of fossil fuels. In the process of exploration and utilization of primary energy resources, in the process of fuel transportation and distribution, in the process of transportation and distribution of fuel, and the application of fuel fixation and movement, carbon emissions are generated, accounting for more than 90% of the total carbon emissions. Therefore, the energy sector is the largest carbon source manufacturing sector.
In addition, the process of using fossil fuels as raw materials and reducing agents in industrial production, changes in biomass, dead organic matter, mineral soil carbon pools in agriculture, forestry and other land uses, fires, the process of applying lime and urea to soils, and waste also contribute to carbon emissions. Therefore, various sectors of the national economy, such as agriculture, industry, and services, contain carbon sources. Forests are the largest carbon sink. Every year, the world’s forests absorb a large amount of carbon dioxide, which plays a very important role in slowing down global warming.
Carbon footprint in English is Carhon Footprint, which refers to the collection of greenhouse gas emissions caused by corporate organizations, activities, products or individuals through transportation, food production and consumption, and various production processes. That is to say, the subject of carbon footprint can be either people, enterprises, or certain types of products. From a human perspective, a carbon footprint reflects the impact of their behavioral awareness on the natural world. The low-carbon economy also advocates residents to change their lifestyles and give up various high-carbon lifestyles, such as taking buses or bicycles more, using less private cars, and saving energy in daily life. From a business perspective, its carbon footprint reflects the impact of production on the natural world. Low-carbon economy also requires enterprises to adopt advanced production technology, eliminate outdated equipment, improve energy efficiency, and realize low-carbon production. For products, it can lead people to change the consumption structure and realize low-carbon consumption, so as to achieve low-carbon industrial structure.
From the measurement scope of carbon footprint, it can be divided into two categories: one is the production carbon footprint, and the other is the consumption carbon footprint. From the perspective of production carbon footprint, the carbon emission of a certain region should be the sum of the net carbon emission of all products it produces, regardless of whether the product is consumed in the region or not, and only limited to a certain region for consideration. Using this method, the carbon emission per unit product in a certain region can be measured, and then the production technology level, environmental protection situation and pollution situation of various products can be understood by comparing with other regions. From the perspective of consumption carbon footprint, the carbon emission of a certain region should be the sum of the net carbon emission of all products it consumes, taking into account other regions related to a certain region, we can analyze the carbon emission per unit product consumption in a certain region, and then think about the consumption structure; at the same time, it is more reasonable to use the idea of consumption carbon footprint to measure a country’s carbon emission reduction responsibility.