In AP Environmental Science, mitigation is any strategy that reduces the cause or severity of an environmental problem, such as replacing ozone-depleting CFCs with substitutes like HFCs (Topic 9.2). Mitigation attacks the source of the problem rather than just coping with its effects.
Mitigation means cutting an environmental problem off at the source. Instead of dealing with the damage after it happens, you reduce the emissions, substances, or practices causing the problem in the first place.
In the CED, mitigation shows up most directly in Topic 9.2 (Reducing Ozone Depletion). Per LO 9.2.A, ozone depletion is mitigated by replacing ozone-depleting chemicals like chlorofluorocarbons (CFCs) with substitutes that don't destroy stratospheric ozone. Hydrofluorocarbons (HFCs) are the classic example, and they come with a built-in plot twist. HFCs don't deplete ozone, but some are strong greenhouse gases. That means one mitigation strategy (saving the ozone layer) created a new problem to mitigate (climate change). APES loves this trade-off, because it shows that environmental solutions are rarely clean wins.
Mitigation is the action verb behind most of Unit 9 (Global Change). LO 9.2.A asks you to describe the chemicals used to substitute for CFCs, and the essential knowledge frames the whole thing as mitigation. The term also matters because APES is a solutions-oriented course. Almost every FRQ ends with some version of "propose and justify a solution," and what you're proposing is usually a mitigation strategy. If you can explain how a policy or technology reduces the cause of a problem (and acknowledge its trade-offs), you're doing exactly what the exam rewards.
Hydrofluorocarbons (HFCs) (Unit 9)
HFCs are the textbook mitigation substitute for CFCs. They spare the ozone layer, but some have a Global Warming Potential thousands of times higher than CO2, so mitigating one problem worsened another.
Montreal Protocol (Unit 9)
The Montreal Protocol (1987) is mitigation written into international law. It phased out CFCs globally, and it's the go-to example when an FRQ asks for a successful environmental policy.
Clean Air Act (Unit 7)
The Clean Air Act mitigates air pollution the same way the Montreal Protocol mitigates ozone depletion, by regulating emissions at the source. Same logic, different pollutants, different unit.
Ultraviolet (UV) radiation (Unit 9)
UV-B reaching Earth's surface is the harm mitigation is trying to prevent. Less CFC emission means more stratospheric ozone, which means less UV exposure and lower skin cancer risk. That cause-to-effect chain is how you explain why mitigation works on an FRQ.
Multiple-choice questions test whether you can identify a mitigation strategy and, more often, evaluate its trade-offs. A common stem describes developing nations switching from CFC-based to HFC-based refrigerants after the Montreal Protocol, then asks you to identify the catch (HFCs are potent greenhouse gases). Other questions compare the Global Warming Potential of HFCs to CO2, or ask why policies first promoted HFCs and now mandate reducing them. On FRQs, mitigation is the move you make in "propose a solution" parts, like the 2021 FRQ on habitat destruction, where you have to describe a realistic strategy that reduces the cause of the problem and explain how it works. Naming a strategy isn't enough; you have to connect it to the mechanism.
Mitigation reduces the cause of a problem; adaptation adjusts to its effects. Banning CFCs is mitigation because it stops ozone destruction at the source. Wearing sunscreen because more UV reaches the surface is adaptation, since the ozone hole still exists and you're just coping with it. On the exam, if the strategy shrinks emissions or removes the harmful substance, call it mitigation.
Mitigation means reducing the cause or severity of an environmental problem at its source, not just dealing with the consequences.
Per LO 9.2.A, ozone depletion is mitigated by replacing CFCs with substitutes like HFCs that do not deplete the ozone layer.
HFCs solved the ozone problem but created a climate problem, because some HFCs are strong greenhouse gases with much higher Global Warming Potentials than CO2.
The Montreal Protocol is the exam's favorite example of successful international mitigation, since it phased out ozone-depleting substances worldwide.
On FRQs, a good mitigation answer names a specific strategy, explains the mechanism by which it reduces the problem, and acknowledges any trade-offs.
Mitigation is any strategy that reduces the cause or severity of an environmental problem. In Topic 9.2, the prime example is replacing ozone-depleting CFCs with substitutes like HFCs, as required under the Montreal Protocol.
Mitigation reduces the cause of a problem (phasing out CFCs so less ozone is destroyed), while adaptation adjusts to the effects (using more sunscreen because UV exposure increased). The exam expects you to keep these straight when evaluating strategies.
No. HFCs don't deplete the ozone layer, but some are powerful greenhouse gases with Global Warming Potentials far higher than CO2. That's why policies that originally promoted HFCs now mandate reducing them, a trade-off the exam tests directly.
No. The CED ties the term most explicitly to Topic 9.2 and LO 9.2.A, but mitigation logic shows up across the course, from the Clean Air Act in Unit 7 to climate solutions and habitat protection in Unit 9 FRQs.
The Montreal Protocol (1987) phasing out CFCs is the strongest one, because you can name the policy, explain the mechanism (fewer ozone-depleting substances reaching the stratosphere), and discuss the HFC trade-off, which hits everything FRQ rubrics reward.