3Y: The Water Cycle & The Carbon Cycle

Question 1

What is the Water Cycle?

Answer 1

Water is continually moving from the Earth’s surface to the clouds and then back to the Earth again as rain and snow. This affects our climate. This in turn affects the habitats on which many plants and animals depend

Question 2

What processes add water to the atmosphere?

Answer 2

1. By far the greatest contributor of water vapour to the Earth’s atmosphere is evaporation from the seas, lakes and land. Water evaporates from the seas leaving the salts behind them.
2. The second factor that contributes water vapour to the atmosphere is plants and trees. Living plants naturally release water vapour from their leaves in a process called transpiration.
3. Another source is industry. Many industrial processes make steam as a byproduct, for example electrical power stations. This adds to atmospheric water vapour.
4. Burning fuels is another factor that adds water vapour to the air. When you burn gas, petrol or home heating oil, water vapour is produced as a byproduct. You can observe cars and gas boilers releasing this water vapour on frosty mornings.

Question 3

What happens to the water vapour as it enters the atmosphere?

Answer 3

1. As water vapour rises, it cools and turns from gas to liquid – a process known as condensation (it loses its latent heat).
2. The vapour is converted to cloud, which consists of very small drops of water.
3. Some of these may be blown by wind (a convection current) over land.
4. As it moves over land it, may be blown higher over mountains and cool further.

Question 4

What happens to the cloud?

Answer 4

1. As the cloud is forced to rise over hills and mountains, it may cool further.
2. The cloud is no longer able to hold on to the water droplets and the water falls as rain, hail, sleet or snow. This is known as precipitation

Question 5

What happens to the water when it reaches the land?

Answer 5

1. Most of the water makes its way back to the sea eventually. Water collects in
   streams, lakes and rivers. This water is known as runoff.
2. Some water can soak deep into the Earth and is stored deep in the ground. This process is called infiltration. The water comes back to the surface
   through ground springs and wells.
3. In mountainous regions, this water may be stored there for several months as snow. When the spring comes the snow may melt, releasing large amounts of water into rivers and streams.
4. In polar regions, snow can stay frozen for thousands of years. Over several years the weight of layers of snow compresses layers below. This can form
   glaciers. 10% of the surface of the Earth is covered with glaciers.

Question 6

What happens to water on its way back to the sea?

Answer 6

1. We can harness some of this water returning to the sea. Hydroelectric
   damscan trap the water and convert itspotential energy into electrical energy in a generator.
2. Some is also routed to our homes and industry for consumption. However, water must be treated before it is consumed. It is treated by filtration and adding chlorine to kill bacteria and viruses.
3. Water that has been used by houses and factories also needs to be treated. Sewage must be treated in sewage treatment plants or in septic tanks built underground near houses in the countryside.

Question 7

What are the benefits of the water cycle?

Answer 7

1. Without the water cycle, the land would be a desert. It would be necessary to irrigate the land to grow crops. This would make the cost of food much more expensive.
2. Without the water cycle there would be a lack of fresh clean water. Water that has evaporated is clean and free of salts. This makes it safe to drink and wash in. If the water cycle did not exist we would have to desalinate (remove salt from) water for drinking, irrigation and washing.

Question 8

Review the Water Cycle Graph:

Answer 8

Review the Water Cycle Graph:

Question 9

What is the Carbon Cycle?

Answer 9

• All living things contain carbon.
• Your body is constantly ‘burning’ compounds of carbon to keep you alive in a process called respiration.
• You exhale carbon dioxide.
• Plants also depend on carbon to stay alive. They can take in carbon dioxide and make food and oxygen from it.

Question 10

How is Carbon dioxide added to the Earths atmosphere?

Answer 10

1. Respiration by living organisms. When living organisms break down food they release carbon dioxide from their cells. In animals this goes into the blood and is released to the air via the lungs.
2. Burning of fossil fuels.
3. Industrial processes.
4. Natural processes. Volcanoes, forest fires and the decay of dead plants and animals release carbon dioxide into the atmosphere.

Question 11

How is Carbon dioxide removed from the atmosphere?

Answer 11

1. Plants. Plants convert carbon dioxide into food and oxygen in a process called photosynthesis.
2. Rain. When rain falls through the atmosphere it reacts with carbon dioxide to
   make a weak acid called carbonic acid.
3. Lakes and seas. A large amount of carbon dioxide dissolves in the oceans and lakes, removing it from the atmosphere. Carbon dioxide is an acidic gas. If more was to dissolve in the world’s oceans and lakes, they would become more acidic, which would affect the types of plants and animals living in them.

Question 12

What is Carbon stored underground as?

Answer 12

1. Oil and gas. They were formed when the bodies of plants and animals settled on the sea bed. This got mixed with mud and buried. Over millions of years, due to the pressure and temperature, the remains of these plants and animals were converted into oil and gas.
2. Coal. It was formed from plants that lived hundreds of millions of years ago in swampy areas. When these giant plants died, they formed layers at the bottom of the swamps. Over time these layers got buried. Under the pressure of the water and layers above, the plants were converted to coal.
3. Turf. It was made from plants that grew in wet areas. When they died, they were prevented from decaying fully by the wet acidic soil. Over time these plants built up to form a thick layer. Eventually over millions of years the turf turned into coal.

Question 13

What is the problem with the carbon cycle today?

Answer 13

• Carbon dioxide in the atmosphere insulates the Earth and keeps heat in.
• This is called the greenhouse effect. This is an entirely natural occurrence.
• Without it the world would be covered in a sheet of ice!
• However, over the past 200 years the concentration of carbon dioxide has increased. This is causing the average temperature of the world to increase.
• The increase in world temperatures due to a rise in carbon dioxide concentrations is called the enhanced greenhouse effect
• The extra warming caused by the enhanced greenhouse effect is called
• *global warming.**

Question 14

What is the main cause of global warming?

Answer 14

The major cause of global warming is the increase in concentration of atmospheric carbon dioxide. This is caused by two main factors:

1. The huge increase in the burning of carbon stores in the Earth, such as fossil fuels.
2. Deforestation. The removal of trees from tropical areas of the world means that there is less plant material available to take carbon dioxide out of the atmosphere.

Question 15

Are there other greenhouse gases?

Answer 15

Yes, Carbon dioxide is only one of a series of greenhouse gases. Others include;

1. Natural Gas (methane). This is produced by dumps, animal slurry and grass-eating animals that generate methane gas in their gut.
2. The CFCs that are used as coolants in older refrigerators and were used in the past as compressed gas in aerosols.

Question 16

What is the problem with global warming?

Answer 16

1. Rise in sea level. As the planet gets warmer, it is predicted that there will be a rise in sea level. This is caused by the expansion of water as it gets warmer. In addition, the faster melting of glaciers in polar regions will contribute to an increase in sea level. It has been predicted that sea levels could rise by 18 cm by the year 2030. Low-lying countries such as the Netherlands and Bangladesh are especially vulnerable.
2. Climate change. It is predicted that as the temperature of the planet increases, there will be more violent storms and that they will become more frequent.

Question 17

What has been done to address the problem of global warming?

Answer 17

• The United Nations called a meeting of all nations of the world. In 1992 many of these countries signed The United Nations Framework Convention on Climate Change. This was an agreement of countries that global warming was happening and that carbon dioxide produced by humans caused it.
• As an extension to this the Kyoto Protocol was signed in 1997 by a number of countries, including Ireland. It commits countries to reduce their emissions of carbon dioxide by agreed targets.
• The 2015 Paris agreement will limit the increase in global warming to less than 2 degrees compared with pre-industrial levels.

Question 18

Has enough been done to address the problem of global warming?

Answer 18

• The Kyoto Protocol did not set large enough reductions for countries to reduce global warming.
• Some of the major producers of carbon dioxide in the world, such as the USA, India, China and Canada, did not legally commit to reduce their emissions of carbon dioxide.
• Ireland has met its commitments under the protocol; however, this was only possible due to the economic recession in 2007. The concentration of carbon dioxide continues to increase.
• However, the 2015 Paris agreement may legally oblige countries to reduce their carbon emissions. At last the problem of global warming is being taken seriously.

Question 19

Why don’t more countries agree to reduce their emissions of carbon dioxide?

Answer 19

• Fossil fuels are a relatively cheap and reliable source of energy. It is expensive to change over from fossil fuels to renewable sources of energy. This would make the cost of energy more expensive for citizens and for industry.
• As countries get more industrialised, they need more energy.

Question 20

What is our government doing to reduce our emissions of carbon dioxide?

Answer 20

Our government is committed to meeting its Kyoto Protocol target and is on track to do so. It has put many policies in place to reduce our release of carbon dioxide into the atmosphere, such as:

1. Improving the building standards of houses so that they use less energy to heat.
2. Giving grant aid to householders to insulate their houses and install more efficient heating systems and solar panels.
3. Placing large taxes on cars that consume a lot of fuel and release a lot of carbon dioxide. This is known as ‘The polluter pays principle’.
4. Placing a carbon tax on fuels.
5. Introducing schemes that encourage private companies to build renewable sources of electricity such as wind energy by allowing them to charge higher prices for electricity generated in this way.
6. Giving a subsidy to companies that provide public transport.

Question 21

What initiatives have worked to date?

Answer 21

1. The new building regulations have reduced the amount of carbon dioxide that a house releases to keep it warm.
2. Similarly there has been a large uptake in the grant aid to upgrade the insulation standards of houses.
3. In Ireland the taxing of cars based on the amount of carbon dioxide released has resulted in people buying more efficient cars. This has reduced the carbon dioxide released from cars by 25 per cent.
4. Carbon tax has made fuels more expensive, encouraging people to use less energy.
5. Subsidising the production of green energy has encouraged a lot of companies to build wind farms.

Question 22

Review the Carbon Cycle Diagram.

Answer 22

Review the Carbon Cycle Diagram.