A changing climate - KS3 Humanities Geography

Climate change and the greenhouse effect

Evidence suggests that climate change has been happening for over 3 million years and that the Earth has undergone dramatic changes to its climate - varying from the ice ages to periods of considerable warming.

Since the 1850s and the the global average temperature has been rising. Many believe that this is down to human activity and the ever increasing use of technology and the burning of fossil fuels to produce energy.

Climate change is driven by a process known as the greenhouse effect. This is where heat is trapped within our atmosphere by naturally occurring gases known as . Without the greenhouse effect this heat would not be trapped and the Earth’s temperature would drop to -50°C.

The Earth absorbs and reflects solar radiation. Greenhouse gases trap heat and warm the Earth. Some radiation is reflected away from the Earth. Pollution adds to greenhouse gases.

However, human activity has now led to what is known as the enhanced greenhouse effect. By burning more fossil fuels and by clearing more land for uses such as agriculture, we are continuing to add more and more of these greenhouse gases to the atmosphere.

As a result more heat is being trapped and the Earth is warming. According to the (Intergovernmental Panel on Climate Change), since 1970 the global average temperature has been rising at a rate of 1.7°C per century. This change alone can have drastic impacts on vulnerable communities around the world.

Natural causes of climate change

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Orbital changes - the Earth's natural warming and cooling periods caused by Milankovitch cycles or variations in the tilt and/or orbit of the Earth around the Sun (Wobble, roll and stretch theory).
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Volcanic activity - during a volcanic eruption carbon dioxide is released into the atmosphere.
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Solar output - there can be fluctuations in the amount of radiation from the sun. If there is a high amount emitted there will be an increase in Earth's temperatures.

Human causes of climate change

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Burning fossil fuels, eg coal, gas and oil - these release carbon dioxide into the atmosphere.
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Deforestation - trees absorb carbon dioxide during photosynthesis. If there are fewer trees, there will be higher levels of carbon dioxide in the atmosphere.
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Dumping waste in landfill - when the waste decomposes it produces methane.
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Agriculture - agricultural practices lead to the release of nitrous oxide into the atmosphere.

Impacts of climate change

We are already beginning to see the impact climate change is having globally, with an increase in droughts, storms, rising sea levels and warming oceans. These events threaten communities and habitats endangering those that live there.

Maldives

One example where climate change is having an impact is the Maldives. This country is made up of chains of islands or (250 of which are inhabited) located in the Indian Ocean.

The islands and atolls are all small, flat and densely populated with the highest point being 2.4m above sea level. With the increase in ocean temperatures the Maldives are increasingly threatened by violent storms.

Climate change also threatens the existence of the Maldives with sea levels projected to rise between 10 to 100 centimetres by the year 2100. Malé, the capital, is especially threatened because it is located on a small, flat, extremely densely populated atoll that is surrounded by sea walls, and other barriers to protect against storms. This means that Malé cannot change shape in response to the rising sea levels and is therefore reliant on expensive engineering solutions.

Aerial view of the island of Male which is the capital of the Maldives.

Wales

The impact of a changing climate is also being felt in Wales. Due to rising temperatures, habitats are impacted by more frequent heatwaves and higher rainfall due to storms. In turn, these are affecting the local plants and wildlife.

Rising sea levels, combined with more intense and frequent storms are increasing the risk of flooding and damage in coastal towns such as Aberystwyth.

Farmers also face challenges too. More rain, warmer temperatures and fiercer storms would make it more difficult to manage crops effectively and make a living.