France and the European Union want to achieve it by 2050. China has its sights set on 2060. So what exactly is this carbon neutrality that countries are aspiring to?
Two Sides of the Scales
Carbon neutrality aims to achieve a balance between:
- On one side, the amount of “greenhouse gases” (GHGs) released into the atmosphere by human activities, which contribute to global warmingGlobal warming, also called planetary warming or climate change... .
- On the other side, the amount of greenhouse gases that can be removed from the atmosphere naturally thanks to forests, soils and oceans, or artificially using man-made technologies.
The Emissions Side
Greenhouse gases mainly include gases that contain carbon molecules, such as carbon dioxide (CO2See Carbon Dioxid ) and methane (ch4)The main component of natural gas deposits and oil deposit gas caps. Methane is produced naturally by landfills... . “Anthropogenic” production (i.e., caused by humans) of these gases has significantly increased since the industrial revolution at the end of the 18th century.
One of the reasons for soaring emissions is the boom in fossil fuelFuel is any solid, liquid or gaseous substance or material that can be combined with an oxidant... production (coalCoal is ranked by its degree of transformation or maturity, increasing in carbon content from... , oil and gas), transportation use, housing construction and the development of industrial, farming and technological processes. Another cause is changes in land use, particularly tropical deforestation to make space for crops, livestock and mines.
The Removal Side
On the other side, CO2 in the atmosphere is absorbed by a natural phenomenon known as photosynthesisProcess used by plants to fuel their growth. Light energy from the Sun is utilized to convert carbon dioxide and water into carbohydrates... and stored (or “sequestrated”) in carbon “sinks”. The biggest such sinks are oceans, soils, grasslands, forests and, more generally speaking, vegetation. We can influence this natural absorption capacity by preserving, restoring or strengthening carbon sinks. Unfortunately, human activities can also destroy or reduce it.
On a smaller scale, there is also the possibility of artificial sequestration, which involves capturing CO2 – especially from the highest-emitting industrial facilities such as powerIn physics, power is the amount of energy supplied by a system per unit time. In simpler terms, power can be viewed as energy output... plants, cement works and steel mills –, transporting it to a suitable geological site and injecting it there for storage for thousands of years. Captured carbon dioxide (co₂)Along with water vapor, carbon dioxide is the primary greenhouse gas (GHG) in the Earth's atmosphere... can also be recycled as a feedstock for other industrial activities.
Two Complementary Approaches
There are two ways to achieve this balance (also called “net zero emissions”):
- Le Cutting emissions by improving energy efficiencyIn economic terms, energy efficiency refers to the efforts made to reduce the energy consumption of a system... in industry and agriculture, using non-fossil energy sources, reducing consumption and, as an extreme measure, potentially even moving toward economic “degrowth”.
- Increasing the planet’s absorption capacity by limiting deforestation and marine pollution or – in the future – by storing huge quantities of CO2 underground.
These methods will all have to be used together. It is estimated that natural carbon sinks eliminate around 10 gigatons (or 10 billion metric tons) of CO2 every year, whereas annual global CO2 emissions exceeded 37 gigatons in 2017. Put side by side, these two figures show just how far we still have left to go.