How do Plants Cool our Air?

Planet Earth is undergoing significant changes in its climate due to human activities. Deforestation is one of the major impacts of human action on climate change.

Evapotranspiration is the process by which water is transferred from the land to the atmosphere. This happens by evaporation from the soil and other surfaces and by transpiration from plants. ^{1, 2} Understanding evapotranspiration highlights the importance of plants in maintaining environmental balance and the need to protect natural vegetation.

This video tutorial can be easily incorporated into science and geography classes. Teachers can use it as a basis for discussions and activities centred on the impact of human activities such as urbanisation, industrialisation, logging and sustainable solutions.

This project is interdisciplinary, integrating concepts from

• mathematics (presenting results and analysing data),
• communication skills (communicating and writing about environmental issues),
• social studies (understanding the impact of deforestation on different regions and communities),
• and physics (physical states of matter and changes of physical state).

Students will develop critical thinking skills, communication abilities, and environmental consciousness.

Evapotranspiration is a process that combines evaporation and transpiration. Evaporation occurs when water in the soil passes from a liquid state to a gaseous state and enters the atmosphere. Transpiration occurs in plants when they release water vapour, through their leaves, into the air. The water that is lost is replaced by water that the plant absorbs from the soil through its roots and distributes throughout the plant. This essential process is part of the water cycle, as it returns water to the atmosphere which leads to the formation of clouds and precipitation.

Evaporation is the physical process by which water (or another liquid) passes from a liquid state to a gaseous state. For evaporation to take place, some molecules on the surface of the liquid must receive enough energy to overcome the forces of attraction between them and escape into the air as vapour. This energy is taken from the surrounding environment. So, when the water molecules evaporate, they take this thermal energy with them and as a result, evaporation has a cooling effect. A common example of this is the sensation of coolness we feel when we sweat: the evaporation of sweat from the skin removes heat from the body, helping to keep us cool.

The architecture of some houses includes a fountain in a central courtyard, such as typical houses in the south of Spain or in Morocco, whose purpose is to lower the temperature on hot days.

Evapotranspiration influences the climate because it has a cooling effect on the air, especially on hot days, and increases atmospheric humidity, leading to greater chances of precipitation.  Understanding evapotranspiration emphasises the importance of plants in maintaining environmental balance and the need to protect natural vegetation.

Deforestation, i.e. the removal of trees, reduces evapotranspiration, affecting local and global climates and leading to a loss of biodiversity. Urbanisation, industrialisation, logging and the cutting down of trees to create fields for crops and pastures for livestock are the main causes of deforestation worldwide. These actions in turn lead to a decrease in evapotranspiration and an increase in the surrounding air temperature.

• Students can conduct an extension of this experiment and measure the amount of water collected on the leaves of the plants on days with different average temperatures (on a warmer day and on a cooler day).
• Advanced learners can measure the temperature of each thermometer every 5 minutes. This creates a more detailed temperature profile.
• Advanced learners could expand the experiment by measuring temperature changes (in wet and dry cotton pads) in different weather conditions, on warmer or colder days, days with more or less wind, in the sun and in the shade. In this way they can try to conclude what accelerates the evaporation of water.

By exploring this experimental activity, children not only discover the impacts of climate change, but can also be inspired to consider future careers in environmental protection. This could be a good opportunity to spark interest in professions that seek to understand and find solutions to climate change, such as: environmental Scientist, climate Scientist and landscape architect.
 

Environmental Scientist

Environmental scientists study how natural elements like trees impact ecosystems and local climates. Environmental scientists are people who study nature and work to keep it safe and healthy. To do this, they first decide what they need to study and plan how to gather information. They often collect samples of things in the environment, like air, soil, and water, so they can study what’s in them. By analysing these samples, they can find out if there are any problems, such as pollution, that might harm plants, animals, or people.

When they find a problem, environmental scientists think of ways to fix it or prevent it from happening again. They also share what they learn with others, like government leaders, companies, and communities, so everyone can help keep the environment safe. To make sure everyone understands their findings, environmental scientists write reports that explain their discoveries and ideas for protecting nature. ³

Environmental scientist video
Environmental scientist, Career Girls
 

Climate Scientist

Climate scientists study changes in the Earth's climate over time and how they might affect the planet in the future. Climate scientists gather information from the air, oceans, and land to see how they’re changing. Some scientists create computer models that show what could happen to Earth’s climate in the future. Others design special tools to measure things like temperature, sea levels, and ice. Many climate scientists work to find ways to reduce climate change and give advice to leaders on how to protect our environment. Some even teach students or give talks to help everyone understand how to take care of our planet. ⁴
 

Landscape architect

Landscape architects design gardens, parks, and public spaces, using trees and vegetation strategically to provide shade, reduce heat, and create more sustainable environments.

Landscape architecture video
Landscape architects video
Landscape architecture, Career Girls