HPU NCS2200 Climate change part 1

• 1. Chapter 21 Climate Change Earth Science and the Environment (4th ed) Thompson & Turk

2. Fig. 21.1a, p.530 3. Fig. 21.1b, p.530 4. Fig. 21.1c, p.530 5. 21.1 Climate change in Earths history Earths early atmosphere very likely had a large greenhouse effect Sun back then was 20-30% fainter Deep freezes occurred five times at least Oceans and all land covered with ice ~700 - 600mya Records show many changes over time Recent records show mean temperature increase from the late 1800s 6. Fig. 21.2, p.531 7. Fig. 21.3, p.532 8. Fig. 21.4, p.532 9. 21.2 Measuring climate change Historical records accounts recorded as records, or in stories Vikings tales of the Little Ice Age (1450-1850) Landscape paintings, other historical & archeological accountings chronicle changes over the span of human history 10. 21.2 Measuring climate change Tree rings growth rings of trees hold climate information Plant pollen the pollen record records what was able to grow, which is linked to temperature and precipitation i.e; 10,500 years ago pines replaced spruce indicating warmer temperatures 11. Fig. 21.7a, p.535 12. 21.2 Measuring climate change Oxygen isotopes in glacial ice 18O & 16O (common isotope) both occur 16O evaporates more readily (lighter), so most ice is heavier Ice from greenland and Antarctica show a record back >100,000 yrs Glacial evidence till, tillites, striations all give information on climate at that time 14C dating of logs preserved in till 13. Fig. 21.6, p.534 14. Fig. 21.7b, p.535 15. 21.2 Measuring climate change Plankton and isotopes in ocean sediment Shells and other hard parts preserved in marine rocks / muds give two lines of information What was alive at the time gives climate information 16/18O ratios in biogenic carbonate Rock and fossil record fossils give much information, what lived when Rock records its formative environment 16. Fig. 21.5, p.533 17. 21.3 Astronomical causes of climate change Changes in solar radiation The suns output varies over time Local activity such as sunspots and solar storms has effect on solar output Changes in global temperature seem to be related to sunspot cycles Direct effect or unknown feedback mechanism? 18. 21.3 Astronomical causes of climate change Bolide impacts some think that an event 65mya blasted enough dust and rock into the atmosphere, that the subsequent cooling killed of the extinction of the dinosaurs (among other things) 19. 21.4 Water and climate Water is in all Earths four spheres The most abundant greenhouse gas Is the substance of clouds (thus all they do) Glaciers and snowfields have very high albedos Evaporation of water transfers heat into the atmosphere Freezing & condensation release heat Moving water weathers, erodes & transports Earth materials Ocean currents move heat poleward from the equator 20. 21.5 The natural carbon cycle and climate Carbon is a small part of the atmosphere, but has large effects CO2 & methane (CH4) are both greenhouse gases and play their role in climate Carbon in the biosphere Carbon IS the biosphere or at least the fundamental building block of life When a thing dies, its carbon is either released (as gas) or preserved (coal swamps, etc) 21. 21.5 The natural carbon cycle and climate Carbon in the hydrosphere CO2 dissolves in water Found as bicarbonate (HCO3 -) and carbonate (CO3)2- in seawater When water warms, gases are released, which aids in further heating 22. 21.5 The natural carbon cycle and climate Carbon in the crust and upper mantle Contains 1,000x as much carbon as is in the atmosphere Carbonate rocks moderate-long term storage of carbon Fossil fuels recoverable fossil fuels contain 5x as much carbon as is in the atmosphere Deeper carbon during subduction, carbonates are consumed and remain trapped 23. Fig. 21.9, p.537 24. Fig. 21.10, p.538 25. Fig. 21.11, p.539 26. 21.6 Tectonics and climate change Position of the continents 200 mya, the single continent Pangea was near the south pole Continental interiors tend to have more severe winters. For a single large landmass, even more so. Influences winds an ocean currents Movement opens and closes straits, etc. 27. 21.6 Tectonics and climate change Mountains and climate Global cooling followed the impact on India and the forming of the Himalayas Many large subdction-related mountains contain carbonate rock Carbonate rock erodes and takes CO2 out of the atmosphere Volcanoes and climate can emit ash and sulfur compounds that cool, or CO2 that warms climate 28. 21.6 Tectonics and climate change The interaction of these to regulate climate When ridges spread slowly, oceans are deeper and sea level falls This exposes carbonate rock which eventually erodes, taking CO2 out of the atmosphere During rapid ridge movement, oceans become shallower Covers up limestone, weathering slows Covers land, decreases global albdeo 29. Fig. 21.12, p.540 30. Fig. 21.13, p.540 31. Fig. 21.15, p.543