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the greenhouse effect


The greenhouse effect is essential to most life on Earth. If the Earth's atmosphere did not create a greenhouse effect, the Earth would freeze over. However, if we turn up the thermostat too much by increasing the greenhouse effect, we may produce too much global warming, which in turn may change our environment forever.


Increased global warming would be serious for humans?



The greenhouse effect causes global warming?



The greenhouse effect is a bad thing?


The greenhouse effect keeps most of the Earth at a nice temperature (for us). It's only if the greenhouse effect is increased that there might be problems. So saying the greenhouse effect is a bad thing is a bit like saying water is a bad thing because we sometimes get floods.

Image of a penguin reading the paper saying "have you heard the world is getting hotter?"



What is the greenhouse effect?


The greenhouse effect, which occurs in the Earth's atmosphere, creates a barrier to stop heat escaping from the Earth. It effectively forms a cosy layer around the Earth, which keeps the surface temperature at an average of 15°C. Without our atmosphere and the greenhouse effect it causes, the surface of the Earth would be a very chilly -18°C.


Some of the radiation from the Sun is absorbed by the land and oceans. This heats the surface and this heat energy is carried away by convection in the atmosphere and by infra-red radiation. Much of this infra-red radition is absorbed by the gases in the Earth’s atmosphere such as water vapour, methane, nitrous oxide and carbon dioxide. As a result, the atmosphere itself warms up and radiates energy not only out into space, but back towards the Earth. It is this complex process we call the Greenhouse Effect.This process was first suggested as the means by which the Earth was warmed by a famous French mathematician called Fourier in 1820, although it was a long time before his ideas were taken seriously.

Jean Baptiste Joseph Fourier

(1768 - 1830)


What is global warming?


For planets, such as the Earth, which have an atmosphere containing gases that can create a greenhouse effect, there is always a delicate balance between the quantity of greenhouse gases in the atmosphere and the resulting temperature on the planet’s surface. It is this balance that may be upset if human activity changes the contents of our atmosphere by, for example, increasing the amount of carbon dioxide. If we do that, the average temperature all over the Earth may increase significantly and we would have global warming, which could possibly lead to serious climate change.

Global Warming

Why is global warming a problem?


Advanced life on Earth has evolved in the present environment and humans have learnt to live on the planet under these conditions. Global warming could change these conditions so that a dramatic change in the balance of life on Earth and the ways humans live might be needed.


It is not the greenhouse effect itself that is bad. A problem only occurs if any changes in the strength of the effect lead to large changes in the Earth's climate on a very short timescale.



Even small changes in temperature could have a devastating effect on the Earth’s climate and environment leading, for example, to more storms, droughts and floods.


***********Press Release**************

News Release - 27th November 2014 - Risk in the UK from extreme weather set to rise

Climate change and population growth will hugely increase the risk to people from extreme weather, a report says. The Royal Society warns that the risk of heatwaves to an ageing population will rise about ten-fold by 2090 if greenhouse gases continue to rise.


They estimate the risk to individuals from floods will rise more than four-fold and the drought risk will treble. “It is impossible for us to avoid the worst and most unexpected events. But it is not impossible to be prepared for an ever-changing world. We must organise ourselves right away."


What causes the amount of different gases in the Earth’s atmosphere to change?


When coal or other fossil fuels are burnt, the carbon in them reacts with oxygen to form carbon dioxide. This increases the amount of carbon dioxide in the atmosphere and can upset the delicate ‘greenhouse’ balance. More energy will be absorbed by the Earth's atmosphere, and this raises the temperature of both the atmosphere and the Earth. Don't forget that plants use up a lot of carbon dioxide from the atmosphere, so we could help regain the natural balance by planting more trees.


Where does the name ‘greenhouse effect’ come from?


A greenhouse is designed to keep plants warm. Visible light comes through the glass and heats the ground and air inside the greenhouse. The main reason a greenhouse then stays warm is that it stops the warm air inside mixing with the colder outside air by the process of convection. A greenhouse is actually an anti-convection house. The process going on in a greenhouse really isn't the same as that in the Earth's atmosphere, but the result might be considered to be similar and so the name seems to have stuck.


What is deforestation?


Trees and plants can soak up a lot of carbon dioxide from the atmosphere during photosynthesis, so one way of helping cut down the amount of carbon dioxide in the atmosphere is to have more plants and trees on Earth. Unfortunately in some areas the exact opposite is happening.


Image of lots of chopped down trees floating in a water penDeforestation is the process of clearing trees from a large area. Of course, we need wood to make furniture, paper and to build houses, and the cleared forest areas make room for fields to grow crops or to build villages and towns. However, it is important to limit the number of trees cut down and to replace them whenever possible to help keep the amount of carbon dioxide in the atmosphere under control.




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