GREENHOUSE EFFECT & GREENHOUSE GASES
The greenhouse effect has a very large influence on Earth’s temperature. Earth absorbs energy from the sun and emits some of it back into space as heat radiation. However, greenhouse gases in the atmosphere such as CO₂, methane and water vapour absorb some of the heat radiation before emitting it again in all directions. Some of the heat escapes into space, but some remains in the atmosphere. The more greenhouse gases there are, the more heat is retained, causing the temperature on Earth to rise.
The Greenhouse Effect
The infographic schematically illustrates the greenhouse effect in Earth’s atmosphere. The image shows a landscape with mountains and a lake, above which the atmosphere with various greenhouse gases is depicted.
Solar Radiation:
In the upper left, the Sun emits energy in the form of sun rays toward Earth. These rays are represented as bright, straight lines that pass through the atmosphere to the Earth’s surface.
Greenhouse Gases in the Atmosphere:
Different greenhouse gas molecules are shown distributed throughout the atmosphere and labeled:
- Carbon dioxide (CO₂): Depicted as black and white molecules
- Methane (CH₄): Shown as blue and black molecular bonds
- Nitrous oxide (N₂O): Depicted as purple and white molecules
- Water vapor (H₂O): Shown as blue and white molecules
- F-gases: Depicted as green and yellow molecular bonds
- Nitrogen (N₂): Shown as purple molecules
- Ozone (O₃): Depicted as blue molecular bonds
Greenhouse Effect Mechanism:
From the Earth’s surface, red arrows rise upward, symbolizing the heat radiation emitted by the Earth toward space. The greenhouse gas molecules absorb part of this heat radiation and then re-emit it in all directions—both back toward Earth and into space. This is illustrated with red arrows pointing in multiple directions.
The infographic demonstrates how greenhouse gases in the atmosphere absorb the Earth’s outgoing heat radiation and re-radiate it in all directions. As a result, part of the heat is retained in the atmosphere, causing the Earth to warm.
GREENHOUSE EFFECT
The natural greenhouse effect maintains Earth’s habitable temperature range. The greenhouse gases responsible for this are released into the atmosphere through natural processes.
The human-made greenhouse effect is also causing temperatures to rise worldwide, which is increasingly changing the climate. The main cause is the burning of fossil fuels, which releases more and more greenhouse gases into the atmosphere. This increases the greenhouse effect, as more greenhouse gases trap more heat in the atmosphere.
GREENHOUSE GASES
The most important greenhouse gases accumulated in the atmosphere by humans are CO₂, methane (CH₄), nitrous oxide (N₂O) and fluorinated gases (F-gases). Water vapour is also a very important greenhouse gas, but like ozone (O₃) it occupies a special position.
THE ROLE OF THE GREENHOUSE GAS CO₂
CO₂ is the best known and most widely emitted greenhouse gas by humans. Its concentration in the atmosphere over the last 11 700 years has remained constant at around 280 ppm (ppm = parts per million; this corresponds to 0.028 %).
Since the industrial revolution from around 1850 on, however, the CO₂ content has already risen by more than half (150 ppm) and is currently 428 ppm (February 2025). This has led to an increase in the average global surface temperature of +1.5 °C for the first time by 2024 and to an above-average +2.9 °C in Switzerland. The Arctic is already warming four times faster than the global average.