Contrary to what is often thought, the greenhouse effect is a beneficial natural phenomenon that provides us with a comfortable temperature on the planet.
When sun rays bathe the Earth in their heat, the ground heats up and sends out infrared radiation into the atmosphere. And it is due to greenhouse gases, including CO2 and water vapor that these warm rays remain trapped in the atmosphere, as if the earth were covered by a bell jar or inside a greenhouse.
Did you know ? Without greenhouse gases, the temperature on Earth would be around -20° as opposed to 15° which is the temperature we now enjoy.
These gases are the result of oil, gas, and coal combustion, fermentation of plants, livestock digestion, and chemical product emission.
Excess greenhouse gas emissions can be harmful over the long term. This is precisely the phenomenon that causes global warming. It is referred to the additional greenhouse effect.
When the Earth is heated by the sun, it emits infrared radiation into the atmosphere. Some of this radiation is trapped by the greenhouse gases that give us a mild temperature on the surface of the planet.
The presence of these gases, most of which are related to human activity, notably since the dawn of the industrial revolution, contribute to the planet’s warming by exacerbating the natural greenhouse effect. This is the additional greenhouse effect. The planet is heating up, resulting in climate change that manifests itself as fires, heat waves, droughts, sea level rise, ecosystem disturbances, glaciation, etc.
Plants and plankton capture carbon dioxide in the atmosphere and transform it into oxygen through a process known as photosynthesis. Forests absorb carbon dioxide and transform it into wood, humus, and oxygen. These phenomena are called “carbon sinks.”
Since the 19th century, humans have been consuming more fossil energies (gas, coal, oil) and releasing much more greenhouse gas into the atmosphere. The average temperature of the planet has increased by 1.1°C since the beginning of the industrial era. In addition to all the highly pollutant industrial activity, deforestation has strongly contributed to destroying carbon sinks, which help guarantee a certain climate equilibrium.
Global warming also gradually causes the melting of permafrost, which in turn releases large amounts of carbon dioxide and methane, probably neutralized for thousands of years. This is notably occurring in Greenland, Alaska, Canada, and Russia.
The most recent projections concerning the Arctic, part of a UN study, demonstrate that winter temperatures will have increased there by 3° to 5° by 2050.
What would happen tomorrow if we stopped all CO2 emissions? Is the phenomenon reversible? Unfortunately, the evaporation times for greenhouse gases can be very long. When comparing water vapor which disappears within a few days in the atmosphere and halogen gases which remain trapped for 50,000, it is clear that the issues are not the same.
If we were to stop everything today, i.e. the emission of excess greenhouse gases contributing to climate change, the mechanisms triggered would continue to act for at least 100 years. The temperatures would continue to rise as long as the infamous incriminated gases were still in the atmosphere.
According to the IPCC, it is crucial to reduce greenhouse emissions around the world from 40% to 70% by 2050 (compared to the 2010 level) and to move toward an economy nearly carbon-neutral during the second half of the 21st century.
The UN raised the alert, a few days before COP26, that the climate outlook would be “catastrophic” if real change is not considered by Member States.
Zeke Hausfather, a climatologist and former researcher at Berkeley, asserts that if the countries responsible for two thirds of worldwide emissions and that have committed to reaching carbon neutrality by 2050 keep their promises, there is reason to hope that one of the most optimist scenarios advanced by the IPCC will be possible.