Climate change

Nature of science:

Assessing claims—assessment of the claims that human activities are producing climate change. (5.2)

• Carbon dioxide and water vapour are the most significant greenhouse gases.
• Other gases including methane and nitrogen oxides have less impact.
• The impact of a gas depends on its ability to absorb long wave radiation as well as on its concentration in the atmosphere.
• The warmed Earth emits longer wavelength radiation (heat).
• Longer wave radiation is absorbed by greenhouse gases that retain the heat in the atmosphere.
• Global temperatures and climate patterns are influenced by concentrations of greenhouse gases.
• There is a correlation between rising atmospheric concentrations of carbon dioxide since the start of the industrial revolution 200 years ago and average global temperatures.
• Recent increases in atmospheric carbon dioxide are largely due to increases in the combustion of fossilized organic matter.

Applications and skills:

• Application: Threats to coral reefs from increasing concentrations of dissolved carbon dioxide.
• Application: Correlations between global temperatures and carbon dioxide concentrations on Earth.
• Application: Evaluating claims that human activities are not causing climate change.

• Release of greenhouse gases occurs locally but has a global impact, so international cooperation to reduce emissions is essential.

Theory of knowledge:

• The precautionary principle is meant to guide decision-making in conditions where a lack of certainty exists. Is certainty ever possible in the natural sciences?

Utilization:

• Syllabus and cross-curricular links:
• Physics
• Topic 8.2 Thermal energy transfer
• Geography
• Part 1.3 Patterns in environmental quality and sustainability/Atmosphere and change
• Environmental systems and societies
• Topic 7.2 Climate change—causes and impacts

Aims:

• Aim 7: Databases can be used to analyse concentrations of greenhouse gases.
• Aim 8: There are interesting parallels between humans that are unwilling to reduce their carbon footprint and cheating in social animals. When the level of cheating rises above a certain level, social behaviour breaks down.

• Carbon dioxide, methane and water vapour should be included in discussions.
• The harmful consequences of ozone depletion do not need to be discussed and it should be made clear that ozone depletion is not the cause of the enhanced greenhouse effect.