What is climate change?

25 November 2014

A quick and simple explanation of climate change and why it matters to you.

Did you know that since 1901 the average global temperature has increased by 0.89oC?

And that the level of carbon dioxide in the atmosphere is approximately 40% higher than pre-industrial revolution levels?

So what?


You might think that an increase in the average global temperature is a good thing, especially if you live in the North of England, but it isn’t. It’s been proven by the boffins that an increase in the average global temperature is changing the climate around the globe and as a result we’re experiencing more severe weather events, changes in rainfall patterns, sea level rises, changes in nature, retreating glaciers and shrinking ice sheets.

So how will this affect you?

The climate in which we live determines what food stuffs we grow, the type of houses we live in, our defence against disease, the location and robustness of infrastructure, our working patterns, the nature we experience and the availability of natural resources.

If the climate changes locally and globally then the provisions we've developed over centuries and the way we live our lives may no longer be feasible. Our houses may not be strong enough to withstand severe weather events, our food stuffs may not grow in wetter or hotter climates, disease may spread, there may be water shortages or flooding events, infrastructure may disappear under the sea and the nature we love may disappear.  If we don’t or can’t adapt to these changes the impact for some of us could be life threatening.    

What determines the climate on planet earth?

The climate is driven by the energy we receive from the sun.  The interaction of this energy, the atmosphere, oceans, ice sheets, land masses and vegetation together create the global and local climate systems.   The climate varies around the globe as a result of these factors and as the climate system is dynamic any change to just one of these interrelated factors will change the local or global climate. 

The planet is kept warm by the presence of greenhouse gases in the atmosphere, without which the heat from the sun would radiate back into space and the planet would be 300C colder.   Greenhouse gases in the atmosphere, including carbon dioxide and water vapour, trap the heat radiated from earth and keep the average global temperature at around 140C.  Greenhouse gases are so good at keeping the planet warm that any changes in concentration will affect the global average temperature.

Greenhouse Gas (1)

How have we caused the climate to change?          

Warming of the planet would occur if we received more energy from the sun, if the concentration of greenhouse gases in the atmosphere increased or if we experienced a large natural event such as an El Nino.  And if the planet warmed, the climate would change.  Scientists agree that the warming we've experienced over the last 100 years is a direct result of the increased concentration of greenhouse gases in the atmosphere.

But where has all this extra greenhouse gas come from? The greatest contributor to the increased levels of greenhouse gas in the atmosphere is the burning of fossil fuels such as coal, gas and oil. They are fuels because they release heat energy when they’re burned. They are fossil fuels because they were formed from the remains of living organisms millions of years ago. 

As fossil fuels contain a high concentration of carbon, when we burn fossil fuels to produce electricity, heat our homes, cook our food and in the engines of vehicles, we release vast quantities of carbon dioxide and other greenhouse gases into the atmosphere. 

In summary

An increase in the concentration of greenhouse gases in the atmosphere as a result of human activity is warming the planet and increasing the average global temperature. This impacts the dynamics of the climate system and results in climate change on a local and global scale. 

218_globaltemp _2013

2013 global surface temperature (Source: NASA)


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