Theories about climate change: Learn about scientists' efforts to explain the phenomenon

CAIRO – 8 November 2022: There are several theories on the subject of climate change including the effect of greenhouses and global warming.

The meaning and importance of climate change are not clear to many, but the following theories reflect the efforts of scientists over the years to explain the phenomenon.

The greenhouse effect

In the 1820s, the French mathematician and physicist Joseph Fourier suggested that the energy that reaches the planet as sunlight must be balanced with energy returning to space because hot surfaces emit radiation.

However, Fourier believed that some of this energy should stay in the atmosphere and not return to space, keeping the Earth warm.

Fourier believed, according to History, the Earth's thin covering of air (atmosphere) works the way a greenhouse does. Energy enters through glass walls, but is trapped inside, like a warm greenhouse.

This theory was further explored by the work of Eunice Newton Foote in the 1850s. Foote's experiments using glass cylinders have shown that the heating effect of the sun was greater in moist air than in dry air and that the highest heating occurred in a cylinder containing carbon dioxide. Her work foreshadowed the work of Irish scientist John Tyndall who also focused on the types of gases that played the greatest role in absorbing heat.

Experts have since realized that the term global warming was an oversimplification, since the infrared radiation released is not completely trapped in the Earth's atmosphere but is absorbed. The more greenhouse gases, the more energy is stored within the Earth's atmosphere.

Greenhouse gases

Irish scientist John Tyndall explored the types of gases most likely to play a role in absorbing sunlight. 

Laboratory tests by Tyndall in the 1860s showed that coal gas (which contains carbon dioxide, methane, and volatile hydrocarbons) was particularly effective at absorbing energy. He eventually showed that carbon dioxide alone behaves like a sponge in the way it can absorb multiple wavelengths of sunlight.

By 1895, Swedish chemist Svante Arrhenius became curious about how lower levels of carbon dioxide in the atmosphere could cool the Earth.

In order to explain past ice ages, Arrhenius wondered if reduced volcanic activity might reduce global carbon dioxide levels. His calculations revealed that if carbon dioxide levels were halved, global temperatures could drop by about 5 degrees Celsius.

After that, Arrhenius wondered if the opposite was true, revising his previous calculations to investigate what would happen if carbon dioxide levels doubled. The possibility seemed remote at the time, but his results indicated that global temperatures would rise by the same amount, i.e. 5 degrees Celsius or 9 degrees Fahrenheit.

Decades later, recent climate modeling confirmed that Arrhenius' numbers were not far from reality.