The greatest threats to the human species are man-made and global warming is here to prove it. When we understand what greenhouse gases are and how they contribute to global warming and climate change, this affirmation becomes even more evident.

Greenhouse gases (GHG) are gases that trap heat in the atmosphere such as water vapour (H2O), carbon dioxide (CO2), and ozone (O3) among others.  They act like a blanket insulating the Earth, and this is called the Greenhouse effect. Without it the Earth’s temperature would be 30 degrees cooler and hostile to life.

The greenhouse effect is a natural phenomenon influenced by natural process. While volcanic eruption releases  greenhouse gases and cause atmospheric alterations, a number of oceanic processes act as carbon sinks, for example.

Human activity has been adding greenhouse gases to the natural greenhouse effect. Gases released from industry and agriculture, for example, are trapping more energy than usual in the atmosphere and therefore increasing the global temperature, causing global warming.


Greenhouse gases are not all the same, they come from different activities, last for a different amount of time in the atmosphere and have different impacts on the planet. Let’s talk about the major GHG:

Water Vapor (H2O) – is the most abundant GHG and its atmospheric concentrations are not linked to human activities directly, but rather to the warming that results from the other greenhouse gases we emit. Warmer air holds more water. H2O remains in the atmosphere for only a few days , but  it is very efficient in absorbing longwave radiation and radiates it back to the surface, thus contributing to global warming.

Carbon dioxide (CO2) – enters the atmosphere through burning fossil fuels – coal, natural gas, and oil, solid waste, trees and other biological materials, and also as a result of certain chemical reactions (e.g., manufacture of cement) and persists for much longer in the atmosphere. It is the commonly GHG produced by human activities and it is responsible for 64% of man-made global warming. This gas is “sequestered” from the atmosphere when absorbed by plants as part of the biological carbon cycle.

Methane (CH4)– is emitted during the production and transport of coal, natural gas, and oil and also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills. Methane is more efficient at absorbing heat than carbon dioxide (as much as 86 times more), making it a very potent greenhouse gas.

Nitrous oxide (N2O) – is emitted during agricultural and industrial activities, combustion of fossil fuels and solid waste, and during treatment of wastewater. While in the atmosphere N2O is exposed to sunlight and oxygen which converts the gas into nitrogen oxides. Nitrogen oxides can damage the ozone layer, which humans rely on to prevent most of the sun’s ultraviolet radiation from reaching the earth’s surface.

Fluorinated gases: Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic, potent greenhouse gases that are emitted from a variety of industrial processes. Fluorinated gases are sometimes used as substitutes for stratospheric ozone-depleting substances (e.g., chlorofluorocarbons, hydrochlorofluorocarbons, and halons). These gases are typically emitted in smaller quantities, but because they are powerful greenhouse gases, known as High Global Warming Potential gases (“High GWP gases”).


Since the Industrial Revolution began in 1750, CO2 levels have risen more than 30%. The world is about 1 °C warmer than before widespread industrialisation, according to the World Meteorological Organization.

 Across the globe, we can see all kinds of consequences: the average sea level increased by 3.6mm per year between 2005 and 2015. Most of this change was because water increases in volume as it heats up.

The effects of a changing climate can also be seen in vegetation and land animals. These include earlier flowering and fruiting times for plants and changes in the territories of animals. Plant and animal extinctions are predicted as habitats change faster than species can adapt. And the World Health Organization (WHO) has warned that the health of millions could be threatened by increases in malaria, water-borne disease and malnutrition.

It seems that While we are fighting a global pandemic, global warming is not going anywhere. That is why it is so important to reduce greenhouse gases emission.

*sources and images: WHO, BBC, Climate Change Project

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