What you’ll learn15 learning objectivesChoose one objective for a focused lesson, or study the complete topic.6.2.1Climate definition• Typical atmospheric conditions• Seasonal temperature and precipitation variationsSyllabus objective6.2.2Anthropogenic CO₂ emissions• Atmospheric CO₂ concentration rising significantly• Accelerated since 1950• Traced to Industrial Revolution (late 18th century)Syllabus objective6.2.3Ice core, tree ring, sediment data• Positive correlation: atmospheric CO₂ and global temperatures• Data for past 800,000 yearsSyllabus objective6.2.4Enhanced greenhouse effect• Anthropogenic GHG emissions• Led to global warming and climate changeSyllabus objective6.2.5Climate change impacts on ecosystems• Local to global scales• Affects resilience, leads to biome shifts• Examples: coral bleaching, desertification, ocean circulation changesSyllabus objective6.2.6Climate change impacts on societies• Various scales and socio-economic conditions• Impacts resilience• Health, water supply, agriculture, infrastructureSyllabus objective6.2.7Climate change models• Systems diagrams with feedback loops• Solar radiation variations, albedo changes, methane releaseSyllabus objective6.2.8Climate change planetary boundary• Evidence suggests already passedSyllabus objective6.2.9Perspectives on climate change• Influenced by many factors• Individual and societal levelsSyllabus objective6.2.10(HL)—Climate data collection• Weather stations, observatories, radar, satellites• Direct measurements: temperature, GHG concentrations• Indirect (proxies): ice core isotopes, dendrochronology, peat pollenSyllabus objective6.2.11(HL)—Global climate models• Manipulate inputs to predict outputs• Uncertainty in inputs and outputs• Hindcasting: test validitySyllabus objective6.2.12(HL)—Climate model scenarios• Predict impacts: sea-level rise, temperature, precipitationSyllabus objective6.2.13(HL)—Critical thresholds and tipping points• Earth may approach critical threshold → new equilibrium• Examples: Antarctic ice sheet melting, Atlantic circulation slowing, Amazon-Cerrado transitionSyllabus objective6.2.14(HL)—Tipping cascades• Two or more tipping points interact• Predictions very uncertainSyllabus objective6.2.15(HL)—Climate justice• Countries vary in responsibility and vulnerability• Least responsible often most vulnerable• Political, economic, equity implicationsSyllabus objective