You may have heard of the term CO2e when reading about climate change and greenhouse gas emissions. But what does it mean and why is it important? In this blog post, we will explain the meaning, definition, calculation, and examples of CO2e.
What is CO2e?
CO2e stands for carbon dioxide equivalent. It is a unit of measurement that allows us to compare the impact of different greenhouse gases (GHGs) on global warming. GHGs are gases that trap heat in the atmosphere and cause the Earth’s temperature to rise. The main GHGs are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases (F-gases).
However, not all GHGs have the same effect on global warming. Each GHG has a different lifespan in the atmosphere and a different ability to trap heat. For example, methane is more potent than carbon dioxide, but it also breaks down faster. To account for these differences, we use a metric called global warming potential (GWP), which measures how much heat a GHG traps over a specific time period (usually 100 years) compared to CO2.
CO2e is calculated by multiplying the amount of a GHG by its GWP. This gives us a common unit that expresses how much warming a GHG would cause if it were CO2. For example, the GWP of methane is 28, which means that one tonne of methane would cause the same amount of warming as 28 tonnes of CO2 over 100 years. Therefore, one tonne of methane has a CO2e of 28 tonnes.
Why is CO2e important?
CO2e is important because it helps us to measure and compare the total GHG emissions from different sources and activities. It also helps us to set targets and policies to reduce GHG emissions and mitigate climate change. For example, the Paris Agreement aims to limit global warming to well below 2°C above pre-industrial levels by achieving net-zero CO2e emissions by 2050.
CO2e also enables us to offset our GHG emissions by investing in projects that reduce or remove GHGs from the atmosphere. For example, planting trees or restoring wetlands can sequester carbon and lower the CO2e emissions. By calculating our CO2e footprint, we can take responsibility for our impact on the climate and take action to reduce it.
Here are some other examples of CO2e emissions from different sectors need reported according to CBAM:
Iron and steel production emits about 2.6 billion tonnes of CO2e per year, accounting for about 7.2% of global GHG emissions from energy use. The main sources of emissions are the use of coal and coke in blast furnaces and the production of direct reduced iron using natural gas. Iron and steel production also consumes large amounts of electricity, which can have high or low emissions depending on the energy mix. To reduce emissions from this sector, technologies such as carbon capture and storage (CCS), hydrogen-based steelmaking, and increased recycling of scrap metal can be deployed
Aluminum production emits about 1.1 billion tonnes of CO2e per year, accounting for about 3% of global GHG emissions from energy use. The main sources of emissions are the use of fossil fuels to generate electricity for electrolysis and the release of perfluorocarbons (PFCs) during the smelting process. Aluminum production also requires large amounts of bauxite ore, which has to be mined and transported. To reduce emissions from this sector, technologies such as inert anode cells, renewable energy sources, and increased recycling of aluminum can be implemented.
Fertilizer production emits about 0.8 billion tonnes of CO2e per year, accounting for about 2.2% of global GHG emissions from energy use. The main sources of emissions are the use of natural gas as feedstock and fuel for the Haber-Bosch process to produce ammonia, which is then used to make nitrogen fertilizers such as urea and ammonium nitrate. Fertilizer production also consumes large amounts of electricity and steam, which can have high or low emissions depending on the energy mix. To reduce emissions from this sector, technologies such as biogas-based ammonia synthesis, CCS, and improved efficiency and optimization of fertilizer plants can be applied.
Electricity generation emits about 13.5 billion tonnes of CO2e per year, accounting for about 37% of global GHG emissions from energy use. The main sources of emissions are the combustion of fossil fuels such as coal, oil, and gas to produce electricity. Electricity generation also requires large amounts of water for cooling and transmission infrastructure for distribution. To reduce emissions from this sector, technologies such as renewable energy sources, nuclear power, CCS, and smart grids can be utilized.