Water Vapour- A Hidden Greenhouse Gas

Water vapour is the most abundant greenhouse gas found in the atmosphere in volume and weight). It is also an efficient greenhouse gas since it absorbs radiation of long wavelengths and then returns it to the surface, helping to cause warming.

Water vapour is often referred to as a key component in this global warming cycle. It is also an essential element in Earth’s water cycle. It is the route all water follows when it travels through the Earth’s atmosphere, land and oceans in liquid water, solid ice, gaseous water, and vapour.

Most water in the atmosphere is evaporated from water bodies, and the rest is the result of transpiration from plants.

The evaporation of water bodies creates 90% of the water that is found in the atmosphere, and the remaining 10 per cent is produced via the transpiration of plants.

The theory is that the presence of water evaporating on one level of the Earth could lead to another day when it is acceptable and won’t harm the environment. We are, however, confronted with the issue of change happening around the globe.

Water vapour is a key greenhouse gas.

It is also true that water vapours are the primary element in the green effect. Still, humans aren’t directly responsible for releasing this gas which can alter its flow throughout the air.

Compared to other greenhouse gases, water vapours are at the surface for only a short time. Most water vapours remain within the air for a few days, almost nine days (before it is deposited). Other greenhouse gases, like methane and carbon dioxide, stay within the air for extended periods (years or even centuries). As a result, it helps in reducing heating. It can take a long time to reach the surface.

Although water vapour could account for around 60% of the Earth’s greenhouse effect, water vapour is not the sole factor affecting Earth’s temperature. Instead, the quantity of water vapour is controlled by the temperature.

Water Vapour- A Hidden Greenhouse Gas
Carbon dioxide is not the primary greenhouse gas.

Water vapour is a greenhouse gas and can change from a gas into a liquid. The concentration of these gases is influenced by how hot the atmosphere is. This water is the only air vapour that can cause pollution in the air. The energy density rises when the atmosphere’s temperature rises, and it becomes hotter.

Climate Feedbacks

Feedback from water vapours is the interaction between the surface temperature. It is a process where changes in radiation disrupt the atmosphere, leading to changes in the water vapours that can either amplify or weaken the temperature increase that started.

An increase in the amount of water vapours in the atmosphere is referred to as the reaction process.

Positive feedback of water vapour

The quantity of water vapours in the atmosphere is directly connected to the temperature. If you increase the temperature, more water evaporates and condenses, and the reverse is true. Therefore, the water evaporates when something causes the temperature to rise (like the release of CO₂ produced by fossil fuels).

Since water vapour is a gas, the additional water vapours will cause the temperature to increase more.

If there were no growth in greenhouse gases, then the amount of water vapour in the atmosphere wouldn’t remain identical to other factors. Adding gases that are not dissolved can cause an elevation in temperatures. That leads to an increase in the amount of water evaporating, which raises the temperature. It is an example of a positive feedback. The heat produced through the expansion of uncondensed air can cause water vapour to get into the air. It enhances the effects of non-condensable gasses.

Clouds and water vapours account for up to 66-85% of the greenhouse effect, in contrast to 9-26% in CO₂. Clouds can absorb Terrestrial radiation (Earth radiation) and decrease the amounts of solar radiation that returns into space. It can cause warming.

Water Vapour- A Hidden Greenhouse Gas
Climate feedback of water vapour

Without feedback from water vapour that CO₂ is a feedback mechanism, a double of CO₂ could raise temperatures by one up to 1.2 degree Celsius. But, the added water vapour released into the atmosphere due to the initial warming causes the temperature to rise by about 1.6degC and positive feedback resulting from the changes to cloud growth that are approximately 0.7degC. It increases (1.3degF).

The way atmospheric water vapour boosts earth’s greenhouse effect

This greenhouse effect has held the planet’s temperature at a level that allowed the development of civilizations in the past few millennia; it is caused by greenhouse gasses, particularly carbon dioxide CO₂, methane CH₄, and some help from nitrous oxide, N₂O and O₃ and ozone.

Research suggests that water vapour can double the temperature rise caused by carbon dioxide. Therefore, if CO₂ causes the temperature to rise by 1 degree C and water vapour is responsible, it will increase the temperature by an additional 1 degree C. For each degree of Celsius that the world’s temperature increases, per the thermodynamic laws, the volume of water vapour in the air can rise by about 7 per cent.

Many believe they are the principal driving force behind global warming. However, increasing the amount of water vapour doesn’t cause global warming. It is more of an outcome. The growth in water vapour levels in the atmosphere is caused by the temperature increase caused by other gases.

Water Vapour- A Hidden Greenhouse Gas
Water vapour in the upper atmosphere amplifies global warming.

The water vapour doesn’t evaporate quickly from the atmosphere when temperatures are high. The water vapour absorbs the heat of the Earth and blocks it from venturing into space.

The global warming potential of H₂O over 100 years is based on five to ten times 10⁻⁴. It also has a significant radiative influence that ranges from -0.1 up to 0.05 W m⁻² for an emission.

The greenhouse effect caused by water vapour is minimal because this excess water vapour is unable to penetrate the upper troposphere. Moreover, the warming caused by greenhouse gases is offset by reflections from the lower cloud cover because of moisture, with very little or no cooling.


Humans are adding carbon dioxide into the atmosphere, and the changes in the water vapour amplify the small changes in the climate. Water is now a problem that impacts the aquatic ecosystems on the planet. Water vapour is the priority of climate scientists. However, water evaporation cannot be managed by humans. It is simply a part of the surroundings.

Author: Mahvish ShamimHi, I am Mahvish Shamim. A chemist, and content writer. I love working with WordPress and doing it the right way. Also passionate about spreading awareness about the environmental crisis. Through my skills, I will deliver high-quality work.

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