Summary
CFCs destroy stratospheric ozone, increasing harmful UV reaching the surface.
In depth
Chlorine and bromine radicals from CFCs catalytically destroy ozone, especially above Antarctica in spring. The 1987 Montreal Protocol phased out CFCs; recovery is expected by mid-century. Ozone absorbs UV-B.
The ozone layer sits in the stratosphere. UV-B causes skin cancer and cataracts and harms phytoplankton. CFC replacements (HFCs) are greenhouse gases and are being phased down.
Common mistake: ozone depletion is not the main cause of global warming.
The stratospheric ozone layer, 15 to 35 km up, absorbs most UV-B and all UV-C radiation. Chlorofluorocarbons (CFCs), used in refrigerants and aerosols, drift up to the stratosphere, where UV frees chlorine atoms that catalytically destroy thousands of ozone molecules each.
The Antarctic ozone hole, discovered in 1985, forms each spring because polar stratospheric clouds boost the reactions. Increased UV raises skin cancer and cataracts and harms plankton and crops. The 1987 Montreal Protocol banned CFCs, and the layer is expected to recover around 2066 over Antarctica.
Example: it is considered the most successful international environmental treaty.
Common mistake: ozone depletion is different from, though linked to, global warming.
Frequently asked questions
What is Ozone Depletion?
CFCs destroy stratospheric ozone, increasing harmful UV reaching the surface.
Which area of biology covers Ozone Depletion, and how advanced is it?
Ozone Depletion is one of the 54 topics in Marine & Environmental Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Global Warming, Greenhouse Effect, Marine Food Webs.
Can you give an example of Ozone Depletion?
The ozone hole peaked around 2000 and is slowly shrinking.
What should I learn before Ozone Depletion?
Work through the Beginner topics in Marine & Environmental Biology first, such as Oceans, Ocean Zones, Plankton, then return to Ozone Depletion. Intermediate topics assume the Beginner vocabulary.
What topics are related to Ozone Depletion?
The closest topics to Ozone Depletion are Global Warming, Greenhouse Effect, Marine Food Webs, Thermohaline Circulation. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Ozone Depletion?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Ozone Depletion. To practise the whole of Marine & Environmental Biology, use the Marine & Environmental Biology quiz.
How is Ozone Depletion different from Global Warming?
Ozone Depletion: CFCs destroy stratospheric ozone, increasing harmful UV reaching the surface. Global Warming: The long-term rise in global average temperature caused mainly by human emission of greenhouse gases. Read both side by side and note what each one explains.
What is a common mistake about Ozone Depletion?
Ozone depletion is not the main cause of global warming.
How should I study Ozone Depletion step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Global Warming and explain the difference aloud. Finally, take the Marine & Environmental Biology quiz and come back to this page for any question you miss.