When referring to emissions in climate talks, people are most likely referring to greenhouse gas emissions. Particularly the emissions that come from human activities and lead to climate change.
In general, the emissions definition in the Cambridge Dictionary is “the act of sending out a gas, heat or light”. Yet considering climate change, the emissions definition also states that the gas harms the environment. So, emissions can be understood in different ways depending on the context.
As mentioned, when talking about emissions and climate change, people are talking about GHG emissions. Particularly carbon dioxide emissions, meaning CO2 emissions. But also methane (CH4) and nitrous oxide (N2O).
What are greenhouse gas emissions?
Greenhouse gases, GHG, are part of the greenhouse effect. The latter is the process that keeps the Earth warm. The most important greenhouse gas is CO2, carbon dioxide. Other examples are methane, nitrous oxide and water vapour. All these gases can absorb heat.
In other words, greenhouse gases trap heat from the sun. Which is a natural part of the greenhouse effect and leads to a warmer climate. However, too many greenhouse gases in the atmosphere lead to a higher temperature than life on Earth is used to. This is the main cause of climate change. Human activities, such as industries, agriculture and the global transport system, release large emissions of greenhouse gases.
For example, CO2 is emitted through the burning of fossil fuels. In detail, the burning of coal, natural gas and oil. Many other things release the gas as well. Such as the burning of waste, trees and other biological materials. More so, the manufacture of cement is a big cause of the emissions. Methane, on the other hand, is emitted through the production and transport of fossil fuels. It is also released by livestock and by the melting of ice. In detail, glaciers store methane in small bubbles in the ice. Therefore, when they melt, methane is released into the atmosphere. The third big GHG gas, nitrous oxide, is emitted through various agricultural and industrial activities.
Negative emissions refer to when GHG emissions are removed from the atmosphere. It is another word that is common to hear in climate change discussions. Negative emissions are reached by capturing and storing GHG gases. It is a crucial part of keeping global warming below the 1.5-degree target. This means that it is not enough to lower or stop emissions from human activities, we will also have to work on removing them.