Environmental impact—global warming

Nature of science:

Transdisciplinary—the study of global warming encompasses a broad range of concepts and ideas and is transdisciplinary. (4.1)

Collaboration and significance of science explanations to the public—reports of the Intergovernmental Panel on Climate Change (IPCC). (5.2)

Correlation and cause and understanding of science—CO₂ levels and Earth average temperature show clear correlation but wide variations in the surface temperature of the Earth have occurred frequently in the past. (2.8)

• Greenhouse gases allow the passage of incoming solar short wavelength radiation but absorb the longer wavelength radiation from the Earth. Some of the absorbed radiation is re-radiated back to Earth.
• There is a heterogeneous equilibrium between concentration of atmospheric carbon dioxide and aqueous carbon dioxide in the oceans.
• Greenhouse gases absorb IR radiation as there is a change in dipole moment as the bonds in the molecule stretch and bend.
• Particulates such as smoke and dust cause global dimming as they reflect sunlight, as do clouds.

Applications and skills:

• Explanation of the molecular mechanisms by which greenhouse gases absorb infrared radiation.
• Discussion of the evidence for the relationship between the increased concentration of gases and global warming.
• Discussion of the sources, relative abundance and effects of different greenhouse gases.
• Discussion of the different approaches to the control of carbon dioxide emissions.
• Discussion of pH changes in the ocean due to increased concentration of carbon dioxide in the atmosphere.

• This issue involves the international community working together to research and reduce the effects of global warming. Such attempts include the Intergovernmental Panel on Climate Change (IPCC) and the Kyoto Protocol which was extended in Qatar.

Theory of knowledge:

• Some people question the reality of climate change, and question the motives of scientists who have “exaggerated” the problem. How do we assess the evidence collected and the models used to predict the impact of human activities?

Utilization:

• Syllabus and cross-curricular links:
• Topics 7.1 and 17.1—equilibrium systems
• Topic 8.2—acid–base equilibria
• Topic 11.3—infrared spectra
• Topic 13.2—transition metal complexes
• Biology topic 4.4—climate change
• Physics topic 8.1—thermal energy transfer

Aims:

• Aim 6: The equilibrium between aqueous and gaseous carbon dioxide could be experimentally investigated.
• Aim 7: Computer modelling is a powerful tool by which knowledge can be gained about the greenhouse effect.
• Aim 8: Discussions of climate change and green chemistry raise awareness of the ethical, economic and environmental implications of using science and technology.

• Greenhouse gases to be considered are CH₄, H₂O and CO₂.