What is the greenhouse effect?

The greenhouse effect is a process by which a planet’s atmosphere traps some of its parent star’s energy, thus warming its surface. In Earth’s case, certain gases – greenhouse gases – trap the Sun’s (our parent star’s) energy to make the planet warm enough to support life.

Without the greenhouse effect there would be no life on Earth – it would be an extremely cold place at night and incredibly hot during the day, just like the Moon.

Just like the glass of a greenhouse keeps the heat inside, greenhouse gases – carbon dioxide, methane, nitrous oxide, ozone and CFCs – do the same with our planet. The two processes are different, however: a glass greenhouse works by reducing airflow and retaining warm air within the structure.

The Greenhouse EffectAccording to Environment Clean Generations: “First, sunlight shines onto the Earth’s surface, where it is absorbed and then radiates back into the atmosphere as heat. In the atmosphere, “greenhouse” gases trap some of this heat, and the rest escapes into space. The more greenhouse gases are in the atmosphere, the more heat gets trapped.” (Image: environment-clean-generations.blogspot.co.uk)

Greenhouse gases trap heat from Earth’s surface

Our planet receives energy from the Sun in the form of sunlight. The Earth’s surface absorbs some of this energy and gets warmer. That is why the tarmac on a road can still feel hot even after the sun has gone down – because it has absorbed some of the Sun’s energy.

The Earth cools down by giving off infrared thermal radiation – a different form of energy. However, before all this radiation can disappear into outer space, greenhouse gases in our atmosphere absorb some of it, which heats up the atmosphere. As the atmosphere heats up, it makes our planet’s surface warmer too – that is the greenhouse effect.

All life on Earth depends on its natural greenhouse effect. Without it life would never have started in the first place. With no greenhouse gases, our planet’s average surface temperature would be -18°C (0°F), instead of the current 15°C (59°F) – our nights would plunge to -153°C (-243°F), while during the day temperatures would soar to 123°C (253°F), just like the Moon’s surface.

Greenhouse effect human and regional contributionsWhen car ownership per 100 inhabitants in India and China, with a combined population of 2.6 billion, reaches the levels of the USA and European Union, the greenhouse effect will intensify significantly and global warming will accelerate. (Image: ucar.edu)

Human activity intensifying greenhouse effect

Human activities, mainly the burning of fossil fuels, deforestation, and livestock farming, have intensified the natural greenhouse effect, causing global warming (climate change). In other words, because of the things we do, our planet is warming up too much.

Some of the ice in and around the North and South Poles is starting to melt – the water is pouring into the sea. Melting polar ice caps will cause sea levels to rise, which could be catastrophic for coastal towns and cities across the world, and also for low lying areas.

The Netherlands, Bangladesh, Florida in the USA, and some other parts of the world where much of the land is close to sea level, could be in serious trouble if sea levels rise by a couple of metres, which scientists say will probably happen by the end of this century unless we start taking measures now.

Greenhouse effect not a new concept

Scientists have known about the greenhouse effect for a long time. According to historic records, it was first mentioned by the French mathematician and physicist Joseph Fourier (1768-1830) in 1824.

The notion and the evidence pointing to the existence of the greenhouse effect was further strengthened by the French physicist Claude Pouillet (1790-1868) in 1827 and 1838, and reasoned from experimental observations by the prominent 19th-century physicist John Tyndall (1820-1893) in 1859.

Swedish physicist-chemist Svante Arrhenius (1859-1927) quantified the effect more fully in 1896. The term ‘greenhouse’ used to refer to this effect was first used by Swedish meteorologist Nils Gustaf Ekholm (1848-1923) in 1901.

Scottish-born Alexander Graham Bell (1847-1922), who is credited with patenting the first practical telephone, said:

“[The unchecked burning of fossil fuels] would have a sort of greenhouse effect. The net result is the greenhouse becomes a sort of hot-house.”

In fact, Bell was so concerned about the greenhouse effect that he advocated the use of alternative energy sources, such as solar power.

Graham Alexander BellAlexander Graham Bell, one of the primary inventors of the telephone, was concerned about what we were doing to the greenhouse effect 100 years ago. He said we should seek out alternative energy sources to fossil fuels. (Image: biography.com)

Some greenhouse gas quotes:

“I do not believe we can effectively move Australia to a lower emission economy, which is what we need to do if we’re going to make a contribution to a global reduction in greenhouse gases, without putting a price on carbon.
(Malcolm Turnbull, Prime Minister of Australia)

“The basic science is very well established; it is well understood that global warming is due to greenhouse gases. What is uncertain is projections about specifics in the next few decades, by how much will the climate change.
(Mario J. Molina. One of the most prominent precursors to the discovery of the Antarctic ozone hole. A co-recipient of the 1995 Nobel Prize in Chemistry)

“There is universal consensus among experts that the earth’s atmosphere is heating up – and that we are responsible for it by putting carbon dioxide in the atmosphere. We also know that the consequences of global warming are catastrophic. But how do we make sure that all countries reduce greenhouse gases?
(Eric Maskin. An American economist and 2007 Nobel laureate. He is credited with laying the foundations of mechanism design theory.)

Video – The Greenhouse Effect

This video animation, by the US Environmental Protection Agency, explains what the greenhouse effect is and how it relates to climate change. The narrator begins by describing our planet’s energy balance and the natural greenhouse effect. She then explains how human activities are intensifying this effect – and producing global warming.