Topic 6-HL and SL

4. A critical threshold where a small alteration in a system component can produce large, potentially catastrophic overall changes.
7. Specific measurements taken from ice cores that serve as proxies to reconstruct past climate conditions.
9. A variable in climate models representing terrestrial surface reflectivity; changes to it create critical feedback loops.
10. The specific atmospheric layer where chemical processes, such as the production of ozone from oxygen, must be explained.
12. The process of reducing or ending the use of energy sources that result in CO2 emissions.
13. A potent greenhouse gas produced in anaerobic conditions with an atmospheric residence time of about 10 years.
15. Indirect data sources, such as dendrochronology or pollen from peat cores, used to build climate models.
17. Economic measures, such as carbon pricing, emissions trading, or subsidies, used by governments to lead climate responses.
18. The geological period that started 2.5 million years ago, characterized by glacial-interglacial cycles.
20. The process of running climate models backwards from the present to verify their accuracy against known historical data.

1. The concept that the least responsible nations are often the most vulnerable to climate impacts.
2. Large-scale, deliberate interventions in the Earth’s climate system, such as space mirrors or ocean fertilization, to treat symptoms rather than causes.
3. The international amendment used to control hydrofluorocarbons (HFCs) that were originally allowed by the Montreal Protocol.
5. Interactions between two or more individual tipping points that make predictions of the scale and pace of climate change highly uncertain.
6. Potent greenhouse gases developed to replace ODSs; they do not deplete ozone but have high global warming potential.
8. The political concept of a state's independent authority, which can create challenges for international climate treaties.
11. The proposed geological epoch characterized by human impacts that will be detectable in the future geological record.
14. A core issue regarding the responsibility for cumulative emissions since the Industrial Revolution and the vulnerability of different nations.
16. Cycles involving the shape of Earth's orbit and tilt that lead to natural climate fluctuations over tens to hundreds of thousands of years.
19. Reactive elements like chlorine and fluorine released into the stratosphere that actively break down ozone molecules.