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TOPIC 1POWERPOINT SLIDESExoplanets (extrasolar planets)-Earth-like planets orbiting other stars-More than 3000 discovered by Kepler mission space telescopeHuman population growth-From 5 billion in 10,000 BC to 6.7 billion in 2007-Colonised Asia, Europe and the Americas from AfricaUnited Nations List of Global issues-Climate change is the single biggest threat to human welfare in the 21stcentury-More pressing than war on terror, global drug war, pandemic diseasesGlobal climate change-Identifiable change in climate of the Earth as a whole over an extended period of time (over decades)-Due to natural processes: climate variability/ natural climate changeoVariations in Earth’s orbitoChanges in solar radiationoVolcanic eruptions-Usually refer to changes forced by human activitiesGreenhouse gas-Gases that cause the greenhouse effect-Any gas in the atmosphere that absorbs and emits radiation within the thermal infrared range (i.e.longwave radiation)-E.g. methane, nitrous oxide, ozone, water vapour, carbon dioxideGreenhouse effect1.Solar energy from the sun passes through atmosphere, some of the energy is reflected back to space2.Earth’s surface is heated by the sun and radiates the heat back out towards space as long waveradiation3.Some of the heat is trapped by GHG in the atmosphereEmission trends across the world-US: 4% of world’s population; 25% total CO2 emissions from 1950-2001-China: 25% world’s population, 8.5% total CO2 emissionsObserved changes and effects-Method of observation:1.CO2 monitoring centre located at Mauna Loa Observatory, Hawaii set up by Charles KeelingoFar away from continents and intense human activities in large citiesoTropical region; not leaning towards the polesoHigh altitude (above inversion layer), avoid local disturbance due to weather processes andhuman activities2.Antarctic Ice Sheets (“natural archive for CO2”)
Consequences of Global Warming:-Heat wave-Prolonged and excessively hot weather, may be accompanied by high humidity in oceaniccountries-Europe (2003, 2018), China (2013, 2018), Hong Kong (2014)-Heat strokes, poor air quality, increased risk of fire-Melting of Ice-Melting of ice sheets in Greenland at unprecedented rate and scale-Loss of Arctic sea ice-Melting of glaciers (e.g. Portage Glacier, Alaska; Kyetrak Glacier, Tibetan Plateau)-Sea level rise-Increase in sea level most notable in Indian Ocean-Coastal regions are susceptible to sea level rise and flooding-Increased drought (California, Northern China)-Increased flood (Pakistan, 2012; South Asia, 2018)-Increased frequency and intensity of storms-Typhoon Haiyan, caused death toll of 6,300-Hurricane Sandy, the biggest Atlantic storm in history-Impact on species and ecosystems-Shifts in migration and ranges; timing shifts-Habitat impactsoWarming will cause substantial reduction in one of the tree dominant species ofbamboo; cause 80-100% of panda habitat to disappear by the end of 21stcenturyoMay drive giant pandas into extinction-Species extinction (e.g. penguins, polar bears)-Coral bleaching (increase in ocean temperature and acidity)-