Announcements

1. Announcements NO CLASS WEDNESDAY! HAPPY THANKSGIVING! No office hours this week. Missing your lab? See the TAs. Apologize for the delays in getting them back

2. NATS 101 Section 4: Lecture 32 Global Climate

3. Classifying the global climate and Earth’s climate record is probably not as exciting as learning about hurricanes or tornadoes, but it important prelude before we get to global warming, the final topic of the course.

4. Some reasons why understanding global climate is important The type of climate in an area is a control on an area’s ecosystem. Plant and animal species are specifically adapted, physically and behaviorally, to climate. Climate affects how human civilization has evolved and adapted to cope in various environments. For example: Agriculture: types of crops and domesticated animals Water supply Types of dwellings and structures built Clothing Social structures, like governments and religions Climate patterns may change due to anthropogenic (human-related) activities—and this is probably already happening. More on that later…

5. Survey question: Which of the following statement best represents your position with respect to the potential impact of weather and climate on our modern American civilization? • Our civilization is totally resilient to weather and climate. • Our civilization is susceptible to disruption from extreme weather and climate events from time to time, for example hurricanes and droughts, but these events are localized and affect a small portion of the population. • Our civilization, as a whole, is highly vulnerable to weather and climate. Changes in weather and climate have the potential to cause widespread societal disruption, and, in the most extreme, dramatically alter or destroy our way of life.

6. Ancient civilizations that succumbed to climate change ANASAZI Four Corners Region Southwest U.S. ARID DESERT CLIMATE MAYA Yucatan Peninsula Mexico TROPICAL WET-DRY CLIMATE PROLONGED DROUGHT PERIODS LIKELY LEAD TO FAMINE AND WAR, AND THESE ANCIENT CIVILIZATIONS WENT INTO DECLINE.

7. We’ve already discussed many of the controls on global climate in previous lectures. I’ll briefly review those and then describe a formal global climate classification system.

8. Climate control #1: Latitude What it does: Controls the intensity of incoming solar radiation. Effects Temperatures decrease with increasing latitude. Effect is more pronounced in wintertime. Largest annual changes occur at higher latitudes. Temperature does not change much in the low-latitude tropics January Average Temperature

9. Climate Control #2: Land-Sea distribution What it does: Water has a higher heat capacity than land, so it heats and cools more slowly than the surrounding land mass Effect on climate: Locations closer to a large water body will: SIBERIA -60 °F January SIBERIA 50 °F • Have less of a seasonal temperature range. • Have a later occurrence of annual maximum and minimum temperature. July Maximum Temperature

10. Climate control #3: Ocean Currents What they do: Giant convective circulations (gyres) transport heat from equator to pole. The warm side of a gyre is typically along the east coast of a continent. The cold side of a gyre is typically along the west coast of a continent. Gulf Stream California Kuroshio Canary Alguhas Bengulas Brazil Humbolt E. Australia Effect on climate Climates on east and west coasts of continents margins are respectively modulated by the presence of warm and cold ocean currents.

11. Climate control #4: the general circulation What it does: Governs the locations where air converges or diverges on a global scale. Effect on climate It is the primary control on the global distribution of rainfall.

12. SAHEL SAHARA DESERT SAHARA DESERT SAHEL CONGO RAIN FOREST SARENGETI CONGO KALAHARI DESERT SARENGETI (UNC Charlotte) KALAHARI DESERT

13. Climate control #5: Terrain What it does: Mountain valley circulations. Monsoons Orographic uplift Effect on climate All of these factors can be potentially very significant controls on the precipitation occurring at a regional scale. As we discussed earlier, these factors are really important for understanding Arizona’s climate! Example of rain shadow effect

14. Köppen climate classification system Developed a climate classification system based on common vegetation types observed throughout the world. Goal was to explain climate in areas that had few or no station observations. Basic Types A = Tropical moist B = Dry C = Moist temperate D = Moist cold E = Polar H = Highland Notations for subtypes derive from German. Wladimir Köppen German climatologist

15. Climates of the world in Köppen system Rest of the lecture is taking the “tour” of this map…

16. Type A: Moist Tropical Climates Characteristics Year-round warm temperatures (above an average of 64 °F) Abundant rainfall (about 60 inches a year) Wet and dry seasons controlled by the position of the ITCZ. Where located Equator to about 15 – 25° latitude. Subtypes Af = Tropical wet Am = Tropical monsoon Aw = Tropical wet and dry

17. Tropical Wet (Af) These regions are tropical rainforests. Typically near the equator. Wettest time of the year is typically during the equinoxes when the ITCZ is nearest to the equator. Temperature hardly varies through the year. Tropical monsoon (Am) climates similar, but have a bit more variation in rainfall.

18. Example Regions:Tropical Wet (Af) Climates CONGO AMAZON INDONESIA \

19. Tropical Wet-Dry (Aw) About 5 - 20° latitude, on the periphery of the ITCZ. Strong annual variation in rainfall, controlled by ITCZ position Summer wet season Winter dry season Savannahs, or large grasslands with scattered trees, like the Sarengeti in Africa.

20. Example Regions:Tropical Wet-Dry (Aw) Climates SAHEL SARENGETI BRAZILIAN HIGHLANDS \

21. Type B: Dry Climates Characteristics Low precipitation most of the year (less than 20 inches). Located under the subtropical high most of the time. Favored on the west side of continents because of cold sea surface temps. Where located About 20 - 40° latitude Subtypes BW = Arid Desert BS = Semi-arid or steppe

22. Arid desert (BW) Receives less than 13 inches of rain per year Hottest temperatures on Earth (e.g. greater than 120 °F) Plants that live in these areas are xerophytes, capable of living long periods without rain. THIS IS THE CLIMATE FOR MOST OF ARIZONA

23. Example Regions:Arid Desert (BW) Climates GOBI DESERT SONORAN DESERT SAHARA ARABIAN DESERT ATACAMA DESERT AUSTRALIAN DESERT KALAHARI DESERT \

24. The driest spot on Earth…where is this??

25. Semi-arid or Steppe (BS) Receive about 8 to 16 inches of rainfall. Short grasses and scattered low bushes and trees. Can get cold in the winter, if in the mid-latitudes. Areas typically are good for grazing animals. In the tropics, typically the transition zone from tropical-wet dry to arid desert.

26. Example Regions:(Mid-latitude) Steppe (BS) Climates CENTRAL ASIA GREAT PLAINS PAMPAS \

27. Type C: Moist Temperate Climates Characteristics Humid with mild winters About 20 to 40 inches of precipitation per year Very different subtypes depending on continental position. Where located About 25 - 40° latitude Subtypes Cfa= Humid subtropical Cfg = West coast marine Cs = Mediterranean

28. Humid Subtropical (Cfa) Typically along east coasts of continents, on the western side of the subtropical ridge. Wet all year round, but slightly more rain in the summer. Hot, muggy summers Supports thick forests or agriculture.

29. Example Regions:Humid Subtropical (Cfa) Climate SOUTHEAST CHINA AND JAPAN SOUTHEAST U.S. EASTERN ARGENTINA AND URUGUAY NORTHEAST SOUTH AFRICA EASTERN AUSTRALIA \

30. West coast marine (Cfb) Located at 40 – 60° latitude Rain throughout the year, especially in winter. More so if on the windward side of mountain range. Receive rain from mid-latitude cyclones hitting west coasts. Proximity to water moderates the climate

31. Example Regions:West Coast Marine (Cfb) Climate NORTHERN EUROPE PACIFIC NORTHWEST SOUTHERN CHILE NEW ZEALAND \

32. Mediterranean (Cs) Located equatorward of the west coast marine climates (30 - 40° latitude) Under the subsiding branch of the eastern side of the subtropical high in summer, so hot and dry then. Wet, mild winters. Short scrubby vegetation with a few trees. Good climate for winemaking!

33. Example Regions:Mediterranean (Cs) Climate MEDITERRANEAN CALIFORNIA SOUTHWEST AUSTRALIA CAPE TOWN AREA CENTRAL CHILE \

34. Mediterranean Climate and the Roman Empire Relatively similar and agriculturally productive climate conditions exist throughout much of the Mediterranean. Same crops that grew in one place would also grow in a another place. FACILITATING FACTOR IN THE EXPANSION OF THE ROMAN EMPIRE AND DEVELOPMENT OF WESTERN CIVILIZATION!

35. Type D: Moist Cold Climates Characteristics Warm to cool summers Cold winters with snow Large seasonal temperature range About 30 - 40 inches of precipitation per year. Where located About 25 - 70° latitude Subtypes Dfa and Dfb = Humid continental Dfc = Subpolar

36. Humid continental (Dfa and Dfb) Typically more toward the eastern side of a continent, poleward of moist subtropical areas. Regular precipitation throughout the year. Summer precipitation maximum. Summers can be sometimes hot. Favorable for deciduous forests and agriculture

37. Example Regions:Moist cold (Df) Climate EASTERN EUROPE AND SOUTHEAST RUSSIA MIDWEST AND NORTHEAST U.S. NORTHEAST ASIA \

38. Subpolar or Boreal (Df) Very cold winters Fairly low precipitation (less than 20 inches per year) Typically supports large evergreen boreal forests, or taiga.

39. Example Regions:Boreal Forests (Df) NORTHERN SCANDANAVIA AND SIBERIA NORTHERN CANADA AND ALASKA \

40. Type E: Polar Climates Characteristics Cold temperatures year round. Tundra, permafrost, or ice cap. Very little precipitation. Where located Poleward of boreal forest THESE REGIONS ARE CHANGING RAPIDLY DUE TO RECENT GLOBAL WARMING.

41. Type H: Highland Climates Climate changes experienced with increasing altitude. Farther up, the typically more “polar” the climate gets. THESE REGIONS ARE ALSO CHANGING RAPIDLY DUE TO THE RECENT GLOBAL WARMING—PARTICULARLY MOUNTAIN GLACIERS.

42. Example Regions:Highland Climates (H) ROCKY MOUNTAINS CENTRAL ASIA AND TIBET ANDEAN ALTIPLANO WE’LL SEE WHAT HAS HAPPENED TO MOUNTAIN GLACIERS IN THESE PLACES LATER…

43. Summary of Lecture 32 The major controls on climate are latitude, land-sea distribution, ocean currents, the general circulation, and terrain. Climate is classified by the Köppen system. TROPICAL MOIST (A): Either rainforest near the equator or savannah farther polward. Precipitation influenced by the ITCZ. DRY (B): Deserts typically located under the subtropical ridge and/or near the west coast of continents. Steppes are grassland transition zones. MOIST TEMPERATE (C): Specific subtype depends on continental position (east vs. west). Moist subtropical on eastern side, west coast marine and Mediterranean on the western side. MOIST COLD (D): Poleward of moist temperate climates, with large seasonal shifts in temperature. Includes boreal forest. POLAR (E): Tundra, permafrost, or ice cap. HIGHLAND (H): Colder climate due to higher elevation.

44. Reading Assignment and Review Questions Reading Chapter 16 (last Chapter to be covered) Chapter 17 Questions Questions for Review: 1,2,3,4,5,7,8,9,10,11,12,13,19 (8th ed.) 1,2,3,4,5,6,7,8,9,10,11,12,13,14,20 (9th ed.) Questions for Thought: 2,3,5,6