Syllabus concepts to know

• 6.4.1 The Sun emits electromagnetic radiation in a range of wavelengths, from low frequency radio waves to high frequency gamma radiation.
• 6.4.2 Shorter wavelengths of radiation (namely, UV radiation) have higher frequencies and, therefore, more energy, so pose an increased danger to life.
• 6.4.3 Stratospheric ozone absorbs UV radiation from the Sun, reducing the amount that reaches the
• 6.4.4 UV radiation reduces photosynthesis in phytoplankton and damages DNA by causing mutations and cancer.
• 6.4.5 The relative concentration of ozone molecules has stayed constant over long periods of time due to a steady state of equilibrium between the concurrent processes of ozone formation and destruction.
• 6.4.6 Ozone-depleting substances (ODSs) destroy ozone molecules, augmenting the natural ozone breakdown process.
• 6.4.7 Ozone depletion allows increasing amounts of UVB radiation to reach the Earth’s surface, which impacts ecosystems and human health.
• 6.4.8 The Montreal Protocol is an international treaty that regulates the production, trade and use of chlorofluorocarbons (CFCs) and other ODSs.
• 6.4.9 Actions taken in response to the Montreal Protocol have prevented the planetary boundary for stratospheric ozone depletion being crossed.
• 6.4.10 ODSs release halogens, such as chlorine and fluorine, into the stratosphere, which break down ozone.
• 6.4.11 Polar stratospheric ozone depletion occurs in the spring due to the unique chemical and atmospheric conditions in the polar stratosphere.
• 6.4.12 Hydrofluorocarbons (HFCs) were developed to replace CFCs as they can be used in similar ways and cause much less ozone depletion, but they are potent GHGs.
• 6.4.13 Air conditioning units are energy-intensive, contribute to GHG emissions and traditionally have contained ODSs.