Global Warming in a Nutshell

An illustration of how greenhouse gases warm the Earth
(source unknown)

Some basic facts about Global Warming, the phenomenon causing Climate Change:

Global Warming has come about  because human beings have been pumping more and more Greenhouse Gases (GHGs) into the atmosphere. People burning fossil fuels like gas, coal, oil, diesel and petrol have been responsible for the increase in GHGs, which scientists tell us has been happening since the Industrial Revolution.

The Purpose of Greenhouse Gases

The temperature of the planet we live on is determined by the balance between the energy from the Sun and how much of that energy is lost into Space. The remaining energy is absorbed by both the land and ocean.

This process warms up both the land and the seas, which then radiate their acquired warmth as long-wave infrared or ‘heat’ radiation. This effect has been measured in the atmosphere and can be reproduced time and time again in the laboratory. We need this greenhouse effect because without it, the Earth would be at least 35 ° Celsius colder, making the average temperature in the tropics about -10 ° C. 

So, in a nutshell, without greenhouse gases the Earth would be too cold for very much to live on, polar bears would live in the tropics and the rest of the planet would be largely uninhabitable. However, you can have too much of a good thing.

Too Much Carbon in the Atmosphere

As snow falls, it is light and fluffy and contains a lot of air. When this snow is slowly compacted to form ice, some of this air is trapped. By extracting these air bubbles trapped in the ancient ice, scientists can measure the percentage of GHGs that were present in the past atmosphere.

Scientists have drilled over two miles down into both the Greenland and Antarctic ice sheets, which has enabled them to reconstruct the amount of GHGs that have been generated in the atmosphere over the last half a million years. Tests on these ice cores reveal that levels of greenhouse gases (GHGs) have gone up and down over the Earth's history, but they have been fairly constant for the past few thousand years. Global average temperatures have stayed fairly constant over that time as well, until recently.

What Is Causing Global Warming?

Global Warming has come about because human beings have been pumping more and more Greenhouse Gases (GHGs) into the atmosphere. People burning fossil fuels like gas, coal, oil, diesel and petrol have been responsible for the increase in GHGs, which scientists tell us has been happening since the Industrial Revolution

Gases in the Earth's atmosphere such as water vapour, carbon dioxide (CO2), methane (CH4), and nitrous oxide are known as greenhouse gases (GHGs) because they warm the Earth's atmosphere by absorbing some of the long-wave radiation from the sun. 

One of the ways in which we know that atmospheric CO2 is important in controlling global climate is through the study of what the Earth's climate has been like in the past. Evidence for past variations in greenhouse gases and temperatures come from ice cores drilled in both Antarctica and Greenland.

For more than 200 years, since the beginning of the Industrial Revolution people in Europe have been burning fossil fuels like oil, coal which were deposited hundreds of millions years ago. Burning these  releases the carbon back into the atmosphere as CO2 and methane (CH4), increasing the ‘greenhouse effect’ and raising the the Earth's temperature.

In effect we are burning fossilised sunlight and this has increased the concentration of atmospheric carbon dioxide (CO2). This human activity is increasing the greenhouse effect and warming the Earth more than is desirable. So too much carbon in our atmosphere is causing the overall temperature of our planet to rise. If this keeps happening we could end up as toast! 

In the last century industrialisation has grown all over the world so that more and more fossil fuels are being burned to keep up with the demand for production. Trees and plants absorb some of the CO2 in the atmosphere, so the clearing of land for agriculture, industry, house building and other human activities has also increased concentrations of greenhouse gases.

If you want to learn more about Global Warming and Climate Change the NASA website explains it well here.