Understandings:
- 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.
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International-mindedness:
- 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.
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