The Greenhouse effect

Higher and foundation tier

The Greenhouse effect

Greenhouse effect Without the natural Greenhouse effect the Earth would be too cold for life. Scientists estimate that the Earth would be some 180C colder without this natural warming effect. The small amount of carbon dioxide and other greenhouse gases such as methane and water vapour in the atmosphere act like a blanket and trap enough of the sun's heat to keep the temperature on our planet within a stable range capable of maintaining life.

The swings in the Earth's temperature and weather which we often complain and moan about so often are very small and mild when compared to the climates on other planets. Our weather and temperature in our atmosphere are both controlled by the presence of certain greenhouse gases. If we increase the amounts of these gases then more of the sun's heat will be trapped in the atmospher and temperatures on Earth will start to rise. This warming of the Earth can lead to climate change which can have a huge affect on all life on our planet.

Over the last 150 years the amount of the greeenhouse gas carbon dioxide in the atmosphere has more than doubled. This is mainly due to:

The carbon dioxide and other gases such as methane are able to trap more of the sun's heat in the atmosphere, this has seen average global temperatures rise. Many scientists believe that this increase in temperature is one of the main drivers for climate change and could cause:

How does the Greenhouse effect work?

The Sun emits short wave infrared radiation which provides the warm needed for life to thrive on Earth. This short wave infrared emitted by the Sun is able to pass through the atmosphere and warm the land and oceans. When the hot land and sea cool back down you might expect the infrared (heat) radiation they give off to escape back into space, however they emit infrared radiation of a longer wavelength which certain gases such as carbon dioxide, methane and water vapour trap and stop it from being emitted into space. The end result is that the heat is trapped in the atmosphere - The Earth warms up, this is the Greenhouse effect.

Greenhouse effect explanation

Time to act?

decisionsSince the industrial revolution, over 180 years ago the average global temperature has risen by about 1.10C. This might not sound like much but many scientists are worried that if the temperature rises by 1.50C then many of the ecosystems on Earth could become permanently damaged, there could be widespread climate change with severe flooding and droughts with more severe and frequent storms/hurricanes/typhoons and the possibility of wide spread impacts on water and food production. Many plants and animals will not be able to adapt or change their behaviour to deal with this new climate and will ultimately through loss of habitat and food become extinct.

Many countries have agreed to cut their emissions of carbon dioxide gas in order to try and prevent further warming. However not all countries have signed up to this pledge, indeed some of the largest producers of greenhouse gases are refusing to cut their emissions in case it damages their economies. At the COP 26 in Glasgow some countries want to delay cutting their emissions until later in this century. With the havoc caused by the Covid-19 pandemic it remains unclear as to how many governments will react in order to revive the economies of their countries. Some campaigners are hoping that a new "world" might emerge following Covid where there could be a green revolution and the accelerated introduction of new greener and less polluting technologies in an attempt to reduce the effects of climate change.

It is important to realise that not everyone agrees that the Greenhouse effect is actually real; there is a small group of scientists who argue that the Earth has gone through natural periods in the past where average temperatures have risen and fallen over time. They would say that it is difficult for scientists to model such complex systems as the Earth's weather and climate. This leads to simplified models, opinions and data which not everyone agrees with. As a scientist you should consider all the facts available and not be swayed by the media or accepted opinion, other people and organizations may have their own agenda which they wish to push, which could result in them twisting or distorting the facts. You need to consider all the information from all available sources before making up your own mind!

Key Points

Practice questions

Check your understanding - Questions on Greenhouse effect and climate change