Global Warming And Its Causes

Floods in South East England December 2013
Flooding is one of many undesirable effects of Global Warming

I wrote a Brief Introduction to Climate Change the other day and tried to keep things short and simple while telling you the main facts.

Today I want to give you the main facts about Global Warming as that is what is causing Climate Change. I shall try and keep it short and simple, too.

Climate Change is caused by Global Warming and Global Warming has come about because too many Greenhouse Gases (GHGs) have been into the atmosphere. People burning fossil fuels like coal 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

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

The temperature of the Earth is determined by the balance between energy from Sun and its loss back into space. About one-third of the solar energy is reflected straight back into space. The remaining energy is absorbed by both the land and ocean. This warms them up, and they then radiate this 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.

Too Much Carbon in the Atmosphere

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 GHGs and temperature come from ice cores drilled in both Antarctica and Greenland. 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.

Since the industrial revolution we have been burning fossil fuels (oil, coal, natural gas) deposited hundreds of millions years ago, releasing the carbon back into the atmosphere as CO2 and CH4, increasing the ‘greenhouse effect’ and elevating the temperature of the Earth. In effect we are burning fossilised sunlight.

Through the burning of fossil fuels and other GHG emissions, humans are enhancing the greenhouse effect and warming Earth.

So there's too much carbon in our atmosphere, which is causing the overall temperature of our planet to rise. If this keeps happening we could end up as toast!

The Greenpeace International website adds:

"A stable climate is a vital foundation for all life on Earth — but our climate is now changing dangerously fast, with widespread and harmful effects on people and the wild places we love.

These serious changes in Earth's climate have happened because the world as a whole is warming up because of something called the greenhouse effect. Global warming doesn't mean everywhere will become warmer, though. Global warming is changing local climates in different ways that can be very harmful to us and our environment. Global warming can cause flooding in some parts of the world and drought somewhere else. Heatwaves, forest fires and rising sea levels are putting millions of people in danger."

What Is Causing Global Warming?

For more than 200 years, since the beginning of the Industrial Revolution people in Europe have been burning fossil fuels like coal and oil and this has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. In the last century industrialisation has grown all over the world so that more and more fossil fuels have been 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, and other human activities has also increased concentrations of greenhouse gases, but to a lesser extent.

So, the sad and inconvenient truth is that you and I are partly responsible for Global Warming and Climate Change.  We probably had no idea that we were creating so much hot air, or CO2. We probably thought our size 9s (size 6s in my case) were responsible for our footprint and had no idea we were also leaving a carbon footprint every time something we did something that caused CO2 to be released into the atmosphere.

I started to find out about all this 14 years ago when I joined the Year of Living Generously, a project that began at the Greenbelt Festival in 2004 and continued for about 7 years. In the meantime my focus has slipped a bit, so I'm writing this blog to help me think about what I can do to shrink my own carbon footprint and live in a more generous and sustainable way, while at the same time I hope it will help people like you think about how they might do the same.

So next time I want to start looking at some of the things you and I can do to make our personal carbon footprint smaller so we can try and stop Global Warming from getting any worse.