In this linked article we are going to look at what causes climate change.
It is always a good idea to make sure that we understand key terms such as climate. People often get confused between the terms weather and climate and sometimes even think that they mean the same thing. Weather is the atmospheric (to do with the atmosphere; the atmosphere is the layer of gas between the surface of the Earth and Space) conditions at a moment in time.
You can see the weather just by looking outside of the window; is the air moving along the surface? If it is we call this wind.
Are there clouds (condensed water) in the air? Is there water moving from the air to the surface? We call this precipitation and it includes rain, drizzle, snow, sleet, fog, mist, dew, frost and rime.
If the sky is not covered in clouds then depending on the time of day the sun could be shining.
You could take a thermometer outside and find out the temperature.
Weather then is the atmospheric conditions at a single point of time; climate is the average of these conditions over a period of time (usually 30 years).
Usually climate is broken down for a place by the average of each month; it is straightforward to work out the average precipitation and usually temperature is given as:
It is important to always make sure that you know which is being used especially if you are packing your clothes to go on a trip like a holiday.
Other atmospheric conditions are a bit more difficult; sunshine can be given as the average number of hours per day.
Wind is usually given in two ways:
Now that we know what climate is we can discuss what is meant by climate change?
Climate change happens all of the time and is natural; weather and climate are almost never the same so there are always slight changes in climate.
The big meeting in Paris and the historic agreement however is about climate change caused by human activity. Sometimes this is called ‘man made’ climate change; but this would be a poor description.
Why might it be poor use of language to use the term ‘man made’?
A better term or adjective to use is ‘anthropogenic’ this is the term used by scientists and the United Nations.
Climate change is the term now used though in the past ‘global warming’ has been used as well as the term the ‘greenhouse effect’.
Anthropogenic Climate Change
Human activities which affect and change the climate can be looked at in two main ways:
We have already briefly discussed the natural ‘greenhouse effect’; certain naturally occurring gasses such as Carbon Dioxide (CO2), Methane (CH4) and water vapour (H2O) have the ability to absorb heat that would otherwise escape in to outer space. As a result these ‘greenhouse gasses’ cause the greenhouse effect which naturally keeps us around 32°C warmer than we would otherwise be based on our distance from the sun.
This is where we add gasses to the atmosphere.
Carbon Dioxide (CO2)
CO2 is added when we burn fossil fuels such as coal, gas and oil. Carbon from ancient times (hundreds of millions of years ago) was locked away underground when living things became buried. Buried forests became mostly coal while the remains of mostly tiny animals that lived in the sea became oil and gas.
Coal, oil and gas are known as fossil fuels. When we burn them in our homes, power stations and petrol/diesel (petrol and diesel are made from oil) engines the Carbon from the fuel joins with Oxygen from the air to make CO2.
The relationship between temperature and CO2 can be seen in these graphs showing both of these over the past 450,000 years. This information has come from drilling deep ice cores.
Methane or CH4 comes from a range of human activities which are related to the rotting or decomposition of dead once living things. Methane as a greenhouse gas is around 20 times more powerful than Carbon Dioxide so it is really important to think about the things we do that produces this gas:
Sinks are traps for greenhouse gasses. An obvious sink is the forests of the world as trees absorb CO2 and lock it up in their trunks, roots and branches.
The fossil fuels such as coal gas and oil are ancient sinks which we are digging up and releasing back into the atmosphere.
There are two main sinks of Methane; firstly huge amounts of this gas are frozen in the soils of the Arctic. These soils are called the permafrost and sadly as temperatures increase in the Arctic the permafrost is melting more and more each year.
Melting Permafrost on the Beaufort Sea
The other main sink for Methane is at the bottom of the world’s oceans and we know that hundreds of millions of years ago runaway global warming of around 8°C happened when such deposits were warmed enough to be released.
Draw up a table headed Emissions and Sinks; under each heading make a brief note of how YOUR day so far has had an effect on BOTH.