Environmental impacts of climate change

EnBy Matt Burdett, 1 March 2018

 

On this page, we look at climate change and the hydrosphere, atmosphere and biosphere, including water stored in ice and oceans, and changing sea levels; carbon stored in ice, oceans and the biosphere; incidence and severity of extreme weather events, including drought; spatial changes in biomes, habitats and animal migration patterns; and changes to agriculture, including crop yields, limits of cultivation, and soil erosion.

 

Note: This page covers each section in brief; for more detail, see their separate pages on this site.

 

The Earth’s spheres

The entire environment of our planet can be studied as different sections called ‘domains’. Each of these domains is a global-scale aspect of the environment. Since the Earth is a sphere, these domains that surround the Earth can also be described as ‘spheres’. The most commonly discussed spheres are:

  • Hydrosphere: All water that surrounds the Earth, including the seas, rivers, glaciers and clouds
  • Atmosphere: The gases surrounding the Earth
  • Biosphere: The living things on Earth

We can also look at two further spheres:

  • Pedosphere: The soil that covers much of the land surfaces of the planet.
  • Lithosphere: Rocks in the upper mantle and the crust. However, there is minimal if any impact on the lithosphere from climate change.

These spheres all interact with one another, and are only separated for ease of study. An impact in one sphere can have consequences on others. The diagram below puts the pedosphere in the middle but in reality, there are lots of ways of interpreting these links.

  • Interactive processes linking the pedosphere with the atmosphere, biosphere, hydrosphere and lithosphere. Nature Education, 2012.

 

The atmosphere and climate change

Climate change is obviously linked to the atmosphere since the climate can be defined as the average conditions of the atmosphere. In the current period of climate change, the most obvious effect is that global surface temperatures are increasing. This can be shown through the ‘temperature anomaly’ which means the difference between the average temperature in a given year and the long term average temperature. A positive value (i.e. above 0 degrees) indicates that the year was warmer than average. The graph below shows that the temperature anomaly has been increasing, indicating that the atmosphere is now almost 1 degree warmer than it has been over the long term average.

  • Global temperature anomaly. A positive value means the atmosphere is warmer than average. Source: NASA, 2017a.

However, this temperature variation is not experienced everywhere at the same rate. Some places warm up faster than others, and other places can experience reductions in overall temperature.

The maps below show the average variation in temperatures at the Earth’s surface in the five years before the date shown, compared to the average temperature between 1884 and 2017. (Note : 1 degree Fahrenheit is equal to around 1.8 degrees Celsius.) It clearly shows that the temperature is rising throughout the 20th century and beyond, but that some areas such as parts of the Southern Ocean (around Antarctica) become somewhat cooler.

  • Global temperature variations (5 year average) compared to average for 1884-2017. A positive value means the atmosphere is warmer than average for the overall period. Source: NASA, 2017b.

The hydrosphere and climate change

They hydrosphere is made up of water, in the form of gas (water vapour in the atmosphere), liquid (fresh water in rivers and lakes, and salt water in seas) and solid (ice in glaciers and ice caps in the polar regions).

The circulation of water in the hydrosphere is known as the hydrological cycle (sometimes called the ‘water cycle’ for younger students). Evaporation from the sea and land adds water vapour to the atmosphere, where condensation occurs turning the vapour into liquid water which then falls as precipitation (including snow, hail, rain and dew). If the precipitation falls onto land, it then passes over and under the ground surface eventually to the sea. This is shown in diagram form below.

  • The hydrological cycle. Source: Tal, 2016.

The level of water stored and transferred through the hydrological cycle is an important indicator of climate change. The links between water and climate mean that changes to water are both a cause and an effect of climate change.

Water as a cause and consequence of climate change: a positive feedback loop

Water vapour is itself a greenhouse gas. It can absorb heat in the atmosphere which in turn allows the atmosphere to warm up. Water is so powerful that it can double the amount of atmospheric warming caused by carbon dioxide alone (Skeptical Science, 2016). This means that if there is an increase in water vapour in the atmosphere, it can increase heat which in turn allows for more evaporation from water in the sea and on land, and therefore more water vapour is added to the atmosphere. This is a type of positive feedback loop. It can lead to changes in atmospheric conditions in cloud cover, precipitation and so on, as well as temperature changes.

The biosphere and climate change

The biosphere includes all the organic material on Earth. Organic matter is anything that is wholly or partly made of living (or dead) things, so it is sometimes considered to include the pedosphere which is soil (see below).

All living things exist within ecosystems, which are local-scale units of interaction. Depending on the viewpoint of the geographer, the scale can vary significantly from something as small as a tree to as large as an entire forest.

Collections of ecosystems with similar characteristics are referred to as biomes. Another way to define a biome is a world scale ecosystem, such as boreal forest, tropical rainforest, or hot deserts. In general, the distribution of biomes is closely related to the distribution of climate. Climate itself usually varies depending on latitude and altitude.

  • The main biomes in the world. Source: Koistinen, 2007.

Changes in the biosphere can be a very long term climate change cause – for example, over millions of years the first green plants changed the atmosphere by increasing the amount of oxygen. However, in the short term (thousands of years) the biosphere has to react to climate change. This can lead to animal migration, extinction and changes in species dominance, as species that are better suited to the new climatic conditions take over. Marine biomes can also be affected. Marine biomes are those under the sea and include coral reefs and mangroves.

The pedosphere (soil) and climate change

The pedosphere refers to the soil layer of the Earth. The pedosphere is an important carbon sink. A carbon sink removes carbon from the atmosphere and traps it. This is known as ‘fixing’ the carbon. Soil does this by trapping the carbon in plant tissue (which the plant itself absorbed from the atmosphere during respiration and photosynthesis). Soil degradation and the clearing of forest for farmland (which itself can lead to soil degradation) is therefore an important concern for climate change. Meanwhile, the soil can also be washed away by more frequent rainfall, or dried out by dry weather and eroded by wind.


Sources

Koistinen, 2007. The main biomes in the world. https://commons.wikimedia.org/wiki/File:Vegetation.png Accessed 28 February 2018.

NASA, 2017a. Global Temperature: Global Land-ocean Temperature Index. NASA’s Goddard Institute for Space Studies (GISS). https://climate.nasa.gov/vital-signs/global-temperature Accessed 28 February 2018.

NASA, 2017b. Global Temperature Time Series: 1884 To 2017. NASA’s Goddard Institute For Space Studies (GISS). https://climate.nasa.gov/vital-signs/global-temperature Accessed 28 February 2018.

Nature Education, 2012. Interactive processes linking the pedosphere with the atmosphere, biosphere, hydrosphere, and lithosphere. Adapted from Lal et al. 1998. https://www.nature.com/scitable/knowledge/library/the-soil-biota-84078125 Accessed 19 February 2018.

Skeptical Science, 2016. Explaining how the water vapor greenhouse effect works. https://www.skepticalscience.com/water-vapor-greenhouse-gas-intermediate.htm Accessed 28 February 2018.

Tal, 2016. The hydrological cycle. https://commons.wikimedia.org/wiki/File:Diagram_of_the_Water_Cycle.jpg Accessed 28 February 2018.


Environmental impacts of climate change: Learning activities

Questions

  1. What is a ‘domain’? [1]
  2. What are the Earth’s main spheres? [4]
  3. Describe the changes in the global temperature anomaly. [3]
  4. Suggest why the atmosphere is warming up. [3]
  5. Suggest why some parts of the world might experience global cooling. [2]
  6. Identify the main stores of water in the hydrosphere. [3]
  7. Explain the positive feedback loop created by an increase in water vapour. [3]
  8. Describe the global distribution of two biomes. [4]
  9. Explain TWO impacts of climate change on the biosphere. [4]
  10. Define ‘carbon sink’. [1]
  11. Explain the role of soil in carbon fixing. [2]

Other tasks

Write a series of questions that could be investigated about each of the different spheres in relation to climate change. Look for the answers on the other sections of this website.

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