1. CLIMATE CHANGE UNIT Chapter 8, 9 & 10

2. How has climate changed from the past? A few summers ago, a15 year old boy in Alberta stumbled upon an enormous bone…. How enermous? The bone belonged to this extinct creature: Wooly Mammoth existed over10,000 years ago when North America was covered in permanent ice (Ice Age).

3. Weather vs. Climate Weather – description of atmospheric condition (temperature, precipitation, wind & humidity) in a particular location over a short period of time (hours, days, weeks) What causes weather? Sun’s Energy heats atmosphere, creates winds, etc. Ocean & lake water evaporates, cools & condenses, creating clouds, rain or snow.

4. Weather vs. Climate Climate is traditionally classified by temperature, precipitation, vegetation Climate – average weather in a region over a long period of time, usually 30 years. New classification based on ecology (landforms, soil, vegetation, human factor as well):  Ecoregions – 867 distinct land- based regions globally  Ecozones – Canada’s own system

5. Weather vs. Climate Bioclimate profiles – graphs that show temp. & moisture at given locations. Predict climate up to 80 years into the future. Factors affecting climate are: Latitude (distance from equator) Presence of large bodies of water Presence of ocean or air currents Land formations Altitude (height above sea level)

6. Earth’s climate system Climate system – complex set of components whose interactions produce Earth’s climate. Sun emits different types of radiation including: Infrared, Visible light, UV – when they hit matters: 1. Radiation is absorbed by particle  gains Energy 2. Transmitted through the particle 3. Reflected off the particle

7. Earth’s climate system Out of 100% of Sun’s radiation: 30% is reflected back to space (6% by atmosphere, 20% by clouds, 4% by Earth’s surface) 70% is absorbed (19% by atmosphere & clouds, 51% by land & oceans)

8. Earth’s climate system Out of those absorbed, less than 1% used for photosynthesis. No OFF switch for the Sun… continous heating! Then how can Earth’s temperature stay pretty constant?

9. Earth’s climate system As Sun’s energy is absorbed: Earth’s surface gains thermal energy (the energy present in motion of particles at a particular temperature) Temperature rises Then Earth surface emits mostly INFRARED radiation back out You get Balance of Energy

10. Latitude & Climate Zones Near Equator: Sun shines directly overhead Energy is spread over small area, thus feel very strong Because Sun is directly overhead  pass through less of atmosphere  less radiation is absorbed and reflected by atmosphere

11. Latitude & Climate Zones Near the Poles, Sun is NOT directly overhead Energy is spread over a larger area, thus feel very weaker. As Sun energy hits at an angle  pass through more atmosphere  more radiation is absorbed and reflected by atmosphere

12. Components of Earth’s Climate System Earth’s climate system keep global temperature constant and support life. Made up of: 1. Atmosphere – layers of gases surrounding Earth 2. Hydrosphere – w ater in liquid, gas and ice forms. 3. Lithosphere - Earth’s rock crust, including land surfaces 4. All living things

13. Components of Atmosphere Made up of: 1. Troposphere – the air we breathe (78% Nitrogen, 21% Oxygen, 1% others) 2. Stratosphere – planes travel here. Ozone layer absorbs UV providing protection. 3. Mesosphere – meteors burn up when reaching mesosphere 4. Thermosphere - space shuttles orbit 5. Exosphere - satellites orbit here

14. Ozone’s location matters Ozone (O 3 ) in Stratosphere: Beneficial, blocked high-energy UV radiation from Sun 1970s saw depletion of Ozone layer due to CFCs (chlorofluorocarbons) – used in A/C, hairsprays, refrigerators 1987 – Montreal Protocol on Substances That Deplete the Ozone Layer was signed

15. Ozone’s location matters Ozone (O 3 ) in Troposphere: Toxic, corrosive effect UV radiation + car exhausts + industrial emissions  toxic chemicals and Ozone gas “Photochemical smog” Ozone in this layer will NOT move up to Stratosphere & provide protection 1 solution: Drive Clean program – testing emissions for older vehicles.

16. The Hydrosphere When water evaporates : Energy is absorbed from surroundings  cooling effect When water condenses: Energy is released into the surroundings  warming effect Water absorbs & store more thermal Energy than land, thus: Cooler near the lake in summer Warmer near the lake in fall. More snow in regions downwind from large water bodies Evaporation Transpiration Condensation Precipitation Surface runoff Groundwater

17. The Hydrosphere - Ice 2% of all Earth’s water frozen: Sea ice (m thickness) in Arctic Ice sheets (km thickness) over land in Antartic & Greenland Glaciers in mountaintop Icebergs – broken off glaciers Surfaces covered in ice reflect MORE of Sun’s energy. Thus, why polar regions are so cold.

18. The Lithosphere Includes solid rock, soil, minerals on land and under oceans. Land formation affects climate zones: Windward has lots of rain leeward has little rain Altitude affects climate zones: Less atmospheric pressure, air rises up, expands and cools down. Rainshadow effect

19. Living Things Living things changes the amount of gases in the atmosphere: Photosynthesis in plants Cellular respiration in animals and plants Methanogenesis in cows, termites

20. 8.6 The Greenhouse Effect Without Earth’s Climate System, the average global temperature ~ minus18 o C. With it, the average global temperature ~ 15 o C. In this system you’ll find a natural, energy-trapping process called greenhouse effect. Infrared radiation that Earth emitted will be absorbed by gases and clouds in the atmosphere, and then radiated  heating up the atmosphere & Earth’s surface.

21. Greenhouse Effect

22. Greenhouse Gases Carbon dioxide (CO 2 ) Before industrial revolution: 280 ppm (parts per million) or 0.0280 % of CO 2 Now: 385 ppm. Sources: volcanic eruption, burning organic matter, cellular respiration, human activity. Carbon cycle = the movement of carbon through living things Carbon sink = absorbs CO 2 from the atmosphere & stores the carbon in another form. Trees, living things and oceans are carbon sinks.

23. Carbon Cycle Vehicle & factory emissions Plant respiration Animal respiration Decomposition Burning of fossil fuel Fossil fuel Photosynthesis Storage in ocean

24. Greenhouse Gases Water Vapour 2/3 of natural greenhouse effects caused by water vapour Positive feedback loop seen:

25. Greenhouse Gases Methane Able to absorb more thermal energy than CO 2 Equivalence: 1 methane = 23 CO 2 Sources: animal digestion (ex: cows) and plant decomposition in swamps Before industrial revolution: 0.700 ppm. Now: 1.785 ppm. Ozone Acts as greenhouse gas in Troposphere layer.

26. Greenhouse Gases Nitrous oxide Equivalence: 1 N 2 O = 300 CO 2 Sources: reactions of bacteria in soil & water. Before industrial revolution: 0.270 ppm. Now: 0.321 ppm. How do they trap IR radiation? N 2 and O 2 only have 2 identical atoms  can only vibrate in 1 direction  cannot absorb various energy. Greenhouse gases have 3 or more atoms  able to vibrate in many directions & thus absorb the energy.

27. Earth is unevenly heated  Energy transfer will occur from areas of more energy to areas of lower energy. Transfer can happen in the atmosphere or in oceans. Remember: Warm air is less dense than cold air Warm air will rise, while cold air will sink Energy Transfer

28. Energy Transfer in Atmosphere Near Equator: Air heats up rapidly  less dense  colder air above falls down  warm air moves up  low pressure area created.

29. Energy Transfer in Atmosphere Warm air is then spreads towards the poles & cools down  cool air sinks  high pressure area created. Above movement is convection current.

30. Energy Transfer in Atmosphere Earth has permanent band of high and low pressure areas Way of energy to be transferred in the atmosphere, from the equator toward North and South poles.

31. Energy Transfer in Atmosphere Air flows from permanent areas of HIGH pressure to LOW pressure  creating prevailing winds. Because Earth rotates, the prevailing winds direction is curved, instead of N-S direction.

32. Prevailing Winds & Climate Zone If prevailing winds pass over oceans: It picks up water vapour  once on land water vapour condenses  rain  create high precipitation areas. If prevailing winds comes from North Pole: It will be cold & dry  as it pass over land, those areas become colder & drier.

33. When water travels to the poles: Water gets colder & more salty (as sea ice forms)  water becomes more dense  sink to ocean floor. Then, Warmer surface water from equator flows towards the poles  replacing the dense water. Energy Transfer in Ocean

34. Thermohaline circulation – continuous flow of water around the oceans due to difference in water temp & salinity. Ocean currents act as conveyor belt to move water slowly from equator to the poles

35. Ocean Currents & Climate Zones Ocean currents can also be caused by winds. Wind effect on climate: Warm ocean currents heat the air above them  warm, moist air reaches land  rainy areas Cold ocean currents cool the air above them  cold, dry air reaches land  cold, dry/desert areas.

36. Ocean Currents & Climate Zones

37. 8.10 Feedback Loops & Climate Positive feedback loop: the effect increases the original cause Negative feedback loop: the effect decreases the original cause Water vapour  Positive feedback loop

38. 8.10 Feedback Loops & Climate 2 different feedback loops, depending whether clouds formed LOW or HIGH within the atmosphere. 1) When warmer temperature creates Low clouds  will trap thermal energy closer to the Earth’s surface  even more warmer temp  POSITIVE feedback loop Warmer temperature More Low clouds

39. 8.10 Feedback Loops & Climate 2) When warmer temperature creates High clouds  will reflect Sun’s radiation back out to space  cooler temperature  NEGATIVE feedback loop

40. 8.10 Feedback Loops & Climate Albedo effect Albedo: a measure of how much of the Sun’s radiation is reflected by a surface. Ex: water (0.08), forest (0.10), fresh snow (0.85)

41. 8.10 Feedback Loops & Climate Albedo effect creates POSITIVE feedback loop on climate When albedo effect is LOW vs. albedo effect is HIGH

42. 8.11 Proxy Records as Clues to Past Climates Proxy records: stores of natural information that we can measure today that tell us what the climate was like in distant past. Examples of proxy records: Ice cores – test for various gases in air bubbles trapped in ice. Show: Greenhouse gases (GHG) have increased dramatically

43. 8.11 Proxy Records as Clues to Past Climates Tree rings – one growth ring per year. Thick ring = good growing condition (warm and wet year). Thin ring = not ideal growing condition (cold & dry year)

44. 8.11 Proxy Records as Clues to Past Climates Coral reefs – grow new layers each season. Show: Temperature of surface ocean water when each layer was growing Rocks – layers of soil & rocks build up over time. Show: plant pollen, fossils, climate in the area

45. 8.11 Proxy Records as Clues to Past Climates Ocean sediment – layer of sediment drift to ocean floor and form layers of rock. Show: fossils of marine plants and animals Caves – rock formations grow as the minerals that are dissolved in dripping water solidify into rocks. Grow faster in rainy weather. Show: how much precipitation occurred at specific times in the past./

46. Evidence of Climate Change 1. Rising temperature 2. Melting glaciers, ice sheets, and sea ice 3. Rising sea level – warmer water expands slightly (thermal expansion)

47. Evidence of Climate Change 4. Changes in severe weather – ex: 2003 heat wave in Europe, hurricane Katrina, tsunamis, etc. 5. Changes in precipitation pattern – S. Africa, S. Asia & Mediterranean getting drier

48. Evidence of Climate Change 6. Changing Season – frequency of cold days decreasing, thus longer growing season. Recall: wine and olive growing in England! 7. Changes in Ecosystem – earlier spring, earlier breeding seasons. Insects can now move to northern areas. Example: New invasive insects found in B.C.