Investigating What Causes Climate Change

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.

Image: Rain-on-Thassos - Edal Anton Lefterov © Wikimedia Commons under Creative Commons Attribution-Share Alike 3.0 Unported / GNU Free Documentation License

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.

Image: High Desert Fog - Jessie Eastland © Wikimedia Commons under Creative Commons Attribution-Share Alike 3.0 Unported

 

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).

Image: Sunset 2007-1 - Alvesgaspar © Wikimedia Commons under Creative Commons Attribution-Share Alike 3.0 Unported / GNU Free Documentation License

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:

• Night time average

• Day time average

• Daily average

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:

• Direction; we always describe a wind based on the direction from which it has come. This is because it brings the characteristics of this region with it. We expect the north wind to be cold in Wales. The direction that the wind comes from for the largest amount of time is called the prevailing wind.

• Speed; usually we want to know what the strength of the wind the wind is like.

Image: Anemometer 2745 - Walter Siegmund © Wikimedia Commons under Creative Commons Attribution-Share Alike 3.0 Unported / GNU Free Documentation License

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.

 

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’.

• Global warming is not really an accurate term as not everywhere on the planet is predicted to actually get warmer. Some models predict the warm ocean currents off the west coast of Wales could be disrupted as a result of climate change. This could cause colder conditions in Wales!

• The greenhouse effect is also a poor use of a term because it is natural and happens without human beings. Certain gasses in the atmosphere trap heat; these gasses act like the glass of a greenhouse keeping our planet warmer than it would otherwise be. Scientists have calculated that without the natural greenhouse effect Planet Earth would be approximately 32°C colder.

Image: Eden project - A1personage © Wikimedia Commons - Public Domain

Anthropogenic Climate Change

Human activities which affect and change the climate can be looked at in two main ways:

• Emissions

• Sinks

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.

Emissions

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.

Image: Men of the Mine- Life at the Coal Face, Britain, 1942 D8263 - Ministry of Information Photo Division Photographer © Wikimedia Commons - Public Domain

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.

Image: Vostok Petit data - NOAA © Wikimedia Commons under Creative Commons Attribution-Share Alike 3.0 Unported / GNU Free Documentation License

Methane (CH₄)

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:

• Waste products such as sewerage, food waste and things like paper and cardboard will all decompose and produce methane.

• Animals especially farm animals such as cows produce large amounts of methane. Meat production as well as dairy produces a lot of methane gas.

• Flooded areas produce methane and rice is produced in flooded fields. Rice production creates large amounts of this powerful gas and rice is the main food crop for nearly half the people on the planet especially in countries such as India, China and their neighbours around Asia.

Image: Biodegradable waste - Muu-karhu © Wikimedia Commons under Creative Commons Attribution-Share Alike 3.0 Unported / GNU Free Documentation License

Sinks

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.

Image: Lacanja burn - Jami Dwyer © Wikimedia Commons - Public Domain

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.

 

Image: Beaufort Permafrost1 - Awing88 © Wikimedia Commons under Creative Commons Attribution-Share Alike 3.0 Unported