The greenhouse gases occur in small amounts in the Earth's atmosphere, yet they have an important role to play in keeping the Earth’s surface warm and able to sustain life. Since the industrial revolution (about 150 years ago), human activities have led to an increase in the emission of greenhouse gases. An increase in these gases in the atmosphere means the atmosphere allows less heat to escape to space, leading to an increase in the average temperature of the Earth’s surface.

Curriculum links

Data, evidence, theories and explanations 1c. how explanations of many phenomena can be developed using scientific theories, models and ideas
Applications and implications of science 4b. to consider how and why decisions about science and technology are made, including those that raise ethical issues, and about the social, economic and environmental effects of such decisions
4c. how uncertainties in scientific knowledge and scientific ideas change over time and about the role of the scientific community in validating these changes.
Environment, Earth and universe 8a. the effects of human activity on the environment can be assessed using living and non-living indicators
8b. the surface and the atmosphere of the Earth have changed since the Earth's origin and are changing at present

Scottish Curriculum

Science - Curriculum for Excellence level 4

SCN 4-04a Planet Earth - Energy Sources and sustainability: By contributing to an investigation on different ways of meeting society's energy needs, I can express an informed view on the risks and benefits of different energy sources, including those produced from plants.
SCN 4-04b Through investigation, I can explain the formation and use of fossil fuels and contribute to discussions on the responsible use and conservation of finite resources.
SCN 4-05b Processes of the planet: Through exploring the carbon cycle, I can describe the processes involved in maintaining the balance of gases in the air, considering causes and implications of changes in the balance.
SCN 4-10b Forces, electricity and waves - Electricity: Using a variety of sources, I have explored the latest developments in chemical cells technology and can evaluate their impact on society
SCN 4-11b. Vibrations and waves: By carrying out a comparison of the properties of parts of the electromagnetic spectrum beyond the visible, I can explain the use of radiation and discuss how this has impacted upon society and our quality of life
SCN 4-18a. Materials - Chemical Changes: I can monitor the environment by collecting and analysing samples. I can interpret the results to inform others about levels of pollution and express a considered opinion on how science can help to protect our environment
SCN 4-20a. Topical Science: I have researched new developments in science and can explain how their current or future applications might impact on modern life.
Chemistry National 4 & 5 Potentially relevant to modules: Nature's Chemistry (N4: fuel, applications of chemistry to everyday life)( N5: application of chemical knowledge to fuelling a modern society), Chemistry in Society (N4: new materials, energy sources) (N5: novel and new materials, including forms of energy generation)
Environmental Science National 4 & 5 Potentially relevant to modules: Sustainability (natural resources and the impact of human activities on them,  sustainability, energy, and waste management. environmental, economic and social impacts, and identifying possible solutions, climate change and pollution). Earth's Resources (resources used in energy production, renewable and non-renewable resources and fuels)
Physics National 4 & 5 Potentially relevant to modules: Energy (sources and uses of heat energy and electrical energy in our society)
Science National 4 Potentially relevant to modules: Fragile Earth (energy resources, benefits and issues and possible solutions, how science is involved in the cause, effect and resolution of environmental issues)


Why are greenhouse gases important?

What are greenhouse gases?

Most of the Earth's atmosphere is made up of nitrogen and oxygen, which do not have much effect in regulating the climate. Other gases that occur in trace amounts (<1% of the atmosphere) have a much bigger impact even though they occur in relatively small quantities. These are known as the greenhouse gases.

Energy (light) from the sun passes through the Earth's atmosphere and is not absorbed by the greenhouse gases (due to its short wavelength). The Earth absorbs this energy and radiates heat energy at a longer wavelength (infrared radiation) back into the atmosphere. The greenhouse gases absorb some of this energy and radiate much of it back towards the surface whilst the rest is radiated out to space. This plays an important role in keeping the Earth's surface warm and able to sustain life. Without this greenhouse effect the Earth would be much colder and life on this planet would be very different. This effect is called the greenhouse effect, because it acts a bit like a glass greenhouse that traps heat creating a warmer environment inside the greenhouse.

greenhouse gas diagram_550

Greenhouse gases include water vapour (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ozone and halocarbons.  John Tyndall was a British scientist working in the 19th century, and a Fellow of the Royal Society. In 1859, he was the first person to show that water vapour and carbon dioxide absorb infrared radiation, and could therefore affect the climate of the Earth.

Some greenhouse gases, such as water vapour and carbon dioxide, occur naturally and enter the environment though natural processes as well as through human activity. Some greenhouse gases, such as fluorocarbons, are created solely through human activities.

Since the industrial revolution (about 150 years ago), human activities have led to emissions and an increase in the levels of greenhouse gases.  An increase in these gases in the atmosphere means the atmosphere traps more heat and allows less heat to escape to space, leading to an increase in the average temperature of the Earth's surface.

Why is this important?

Rising temperatures may lead to changes in weather, sea levels and affect how land can be used. These changes are commonly referred to as climate change. Scientists predict even a small increase in the average temperature (about 1°C) could lead to increases in more extremes of weather including increased rainfall in some places, rising sea levels and more heat-waves and decreases in some such as cold spells. There could also be greater risk of drought in some countries in Africa and Asia and possibly more intense hurricanes.

Although it is already too late to stop climate change completely, making changes now could prevent it getting much worse. The climate change act (a law passed by the UK government in 2008) commits the UK to reduce its greenhouse gas emissions by 80% by 2050 across all sectors of the economy.