1. Chapter 8: Climate and Climate Change

2. Climate Classification
Purpose of Classifying Climates
Understand climate distribution
Compare climates of different places
Temperature & precipitation typically used
Vegetation
Earliest scheme = ancient Greeks 2200 years ago
Classified 3 climate regions based on latitude
Torrid, Temperate, Frigid
Figure 8-1

3. Climate Classification
Köppen climate classification system
Based on annual & monthly average temperature & precipitation
A, B, C, D, E, H*
4 of 5 major groups classified by temperature
5th group classified by precipitation
Subdivided further based on temperature & precipitation relationships
Figure 8-2

4. Climate Classification
Köppen 3 letter code system
1st = group
2nd = precipitation
3rd = temperature

5. World Distribution of Major Climate Types
Weather records: How do we explain their locations?
Figure 8-11

6. World Distribution of Major Climate Types
Three Questions
Where are various climate types located?
What are the characteristics of each climate?
What are the main controls of each climate?
Climograph
Graphic representation of monthly temperature & precipitation
Figure 8-4

7. World Distribution of Major Climate Types
Tropical Humid Climates (A)
Tropics (0-25° N/S)
Winterless climates; little temperature change
High temperatures & prevalent moisture
Precipitation influenced by ITCZ
3 subtypes
Divided based on monthly rainfall
Figure 8-5

8. World Distribution of Major Climate Types
Figures 8-6a & b
Tropical wet climate (Af)
Equatorial (0-10º N/S)
Monotonous
Daily temperature range > annual range
High humidity
High precipitation
Multiple rains daily
Afternoon convective storms
Evenly distributed rain during year
Influenced by ITCZ
High solar angle year round

9. World Distribution of Major Climate Types
Figures 8-8a & b
Tropical savannah climate (Aw)
N/S of Af climates
Most extensive A climate
Seasonal wet/dry alteration due to ITCZ position
Lowest tropical rainfall amounts
Dominant Controls
Summer: ITCZ
Winter: cT or cP air masses

10. World Distribution of Major Climate Types
Figures 8-10a & b
Tropical monsoonal climate (Am)
Prominent monsoon wind patterns
Coastal areas
Extensive rainfall during “summer”
Cherrapunji, India = 425 in
Cloud cover reduces summer temperatures
Dominant Controls
ITCZ movement
Jet stream fluctuation
Continental pressure changes

11. World Distribution of Major Climate Types
Dry climates (B)
Cover about 30% of land area worldwide
Dry conditions all year
PE > P
Lack of uplift or lack of moisture
2 main types (precipitation)
Desert
Steppe
2 subtypes (temperature)
Subtropical
Midlatitude
Figure 8-12

12. World Distribution of Major Climate Types
Figures 8-14a & b
Subtropical desert climate (BWh)
Near STH’s (30° N/S)
Precipitation is scarce, unreliable, intense & short-lived
Hot temperatures
Large daily temperature range
Dominant Controls
Subsidence from (STHs)
Cold ocean currents

13. World Distribution of Major Climate Types
Subtropical steppe climate (BSh)
Fringe BWh climates
Separate deserts from humid climates
Less extremes
Cooler & more rainfall (semi-arid)
Seasonal rainfall concentration
Dominant Controls
Similar to BWh
Figure 8-17

14. World Distribution of Major Climate Types
Figures 8-18a & b
Midlatitude desert climate (BWk)
Meager & erratic precipitation
Mostly in summer
Cooler temperatures
Hot summers & cold winters
Greater annual & daily temperature range
Dominant Controls
Rain shadow effects
Distance from moisture sources

15. World Distribution of Major Climate Types
Midlatitude steppe climate (BSk)
Rringe BWk climates
Transition between desert & humid climates
More precipitation than mid-latitude deserts (semi-arid)
Less temperature extremes than mid- latitude deserts
Dominant Controls
Similar to BWk
Figure 8-19

16. World Distribution of Major Climate Types
Mild Midlatitude Climates (C)
Transition between warmer tropical climates & colder severe midlatitude climates
Equator-ward side of mid-latitudes
Long, hot summers & short, mild winters
Highly variable precipitation
3 primary groups
Figure 8-20

17. World Distribution of Major Climate Types
Figures 8-21a & b
Mediterranean Climate (Csa, Csb)
West sides of continents
Modest precipitation in winter, summer is virtually rainless
Mild, wet winters & hot, dry summers
Clear skies especially in summer
Dominant Controls
Summer: STH
Winter: westerlies & cyclones

18. World Distribution of Major Climate Types
Humid Subtropical Climate (Cfa, Cwa)
East sides of continents
Warm to hot summers; high humidity
Hot & humid
Precipitation reaches summer maximum, less in winter
Winter temperatures are mild to cold
Figures 8-24a & b

19. World Distribution of Major Climate Types
Figures 8-26a & b
Marine West Coast Climate (Cfb, Cfc)
West sides of continents
Often cloudy with precipitation
Wettest of midlatitudes
Max precipitation in winter
Temperate climate
Very mild winters for latitude
Dominant Controls
Westerly winds & oceanic influence year-round

20. World Distribution of Major Climate Types
Severe Midlatitude Climates (D)
Only in Northern Hemisphere
Continentality—remoteness from oceans
Large annual temperature range
Precipitation varies; diminishes inland & poleward
4 recognizable seasons
Long, cold winter & shorter summer
Subdivided into 2 types
Figure 8-27

21. World Distribution of Major Climate Types
Humid Continental Climate (Dfa, Dfb, Dwa, Dwb)
East sides of continents in N. Hemisphere
Dominated by westerlies & frequent weather changes
Warm/hot summers, cold winters
Large annual temperature range
Generally low precipitation
Higher near coasts
Winter precipitation = cyclones; summer precipitation = convection
Our climate in NE
Figures 8-28a & b

22. World Distribution of Major Climate Types
Subarctic Climate (Dfc, Dfd, Dwc, Dwd)
Winters are long, dark, bitterly cold
Summers are short
Spring & fall are very short
Coldest temperatures; little precipitation
Largest annual temperature ranges
(-90 °F to 98 °F in Verhoyansk, Siberia)
Dominant Controls
Continentality
Alternate between:
Westerlies/storms
Anticylcones
Figures 8-31a & b

23. World Distribution of Major Climate Types
Polar Climates (Group E)
Receive little insolation
Coldest summers
No average temperature above 50 °F
Large annual temperature range
Small daily temperature range
Extremely dry, but classified as non-arid
Low evaporation
2 primary groups
Figure 8-27

24. World Distribution of Major Climate Types
Tundra Climate (ET)
Long, dark winters
Winters not as severely cold as subarctic climate
Brief, cool summers
Little precipitation
Dominant Controls
Latitude
Distance from heat/moisture sources
Extreme contrasts in sunlight/darkness
Polar anticyclones
(A & cP air masses)
Figures 8-33a & b

25. World Distribution of Major Climate Types
Figures 8-34a & b
Ice Cap Climate (EF)
Greenland & Antarctica
Permanent ice & snow cover
High latitude with high altitude
Very limited precipitation
Polar deserts
Dominant Controls
Similar to ET

26. World Distribution of Major Climate Types
Highland Climate (H)
Infinite variations from place to place
Vertical climate zonation
Altitude vs. Latitude
Altitude = more significant in highlands
-6.5°C /1000m
Exposure: windward or leeward
Figure 8-36

27. Global Patterns Idealized
Understand climate locations & relationships
Presumed arrangement of climate types on hypothetical continent
Example: Africa
Only continent with equal land N/S of equator
Figures 8-39 & 40

28. Global Climate Change Changes in climate on long time scales
Episodic events vs. long-term global climate change
Numerous time scales
70 million years: global cooling trend
150,000 years: temperature fluctuated
10,000 years: sharp warmup
150 years: warming trend relative to last 1000 years
Figure 8-41

29. Global Climate Change Paleoclimatology Dendrochronology
Proxy measures of climate
Dendrochronology
Study of past climate via tree ring analysis
Oxygen isotope analysis/Ice cores
Lighter vs. heavier isotopes (18O : 16O)
Ratio of 18O/ 16O = thermometer
Atmospheric composition measurements
Coral reefs
Ratio of 18O/ 16O & reef height
Pollen data
Radiocarbon dating
Figure 8-42

30. Global Climate Change Causes of Long-Term Climate Change
Atmospheric aerosols
Block insolation & lower temperature
Due to volcanic eruptions or asteroid impacts
Anthropogenic impacts
Solar output fluctuations
Sunspot activity vs. solar output
Roles of the oceans
Absorb large amounts of carbon
Methane hydrates
Heat transfer from low latitudes to high latitudes
Figures 8-43 & 45

31. Global Climate Change Climate change causes (cont.)
Greenhouse gas concentrations
Greenhouse gas concentrations related to temperature
Evidence of CO2 increase being anthropogenic
Feedback mechanisms
Positive feedback mechanisms
Negative feedback mechanisms
Variations in Earth-Sun relations
Milankovitch cycles
Shape of Earth’s orbit (eccentricty)
Inclination of Earth’s axis (obliquity)
Position of Earth’s axis (precession)
Figure 8-44

32. Global Climate Change Evidence of global warming
Figures 8-46a & b
Evidence of global warming
11 of 12 warmest years on record occurred between 1995–2006
Global temperature increasing
Arctic temps ↑ 2 x’s global rate
Ocean temperatures increasing
Sea level rise
Thermal expansion
Melting ice caps & glaciers
Arctic sea ice decreasing
# of intense tropical cyclones ↑
Water vapor in atmosphere ↑
Changes in precipitation amounts

33. Global Climate Change Evidence of current global warming (cont.)
Concentrations of carbon dioxide correlated with temperature
Carbon dioxide concentrations correlate with increased anthropogenic greenhouse gases
Carbon dioxide increasing at a rate faster than observed in last 800,000 years
Figure 8-F

34. Global Climate Change Consequences of global warming
Projected climate in the upcoming century
Climate will warm about 0.4°F per decade
Changes will be greater than those during 20th c.
Estimated temperature increase from 3.3°F - 7.2°F
Sea level rise
Stronger tropical cyclones
Increased precipitation
Figure 8-47a

35. Global Climate Change Climate models Addressing global warming
Figure 8-47b
Climate models
General circulation models (GCMs)
Numerous assumptions
Model accuracy
Addressing global warming
Kyoto protocol
Standards for new industrialized countries
Mitigating & adapting

36. Summary Climate is classified based on precipitation and temperature
There are six primary groups of world climates
The tropical humid climates exist at tropical latitudes and are characterized by warm, constant temperatures and rainfall
Dry climates exist near the subtropics and are characterized by hot, dry conditions
Mild midlatitude climates constitute a transition between warmer tropical climates and cold severe midlatitude climates
Mild midlatitude climates typically have long, hot summers & mild winters, and have modest precipitation
Severe midlatitude climates only occur in the Northern Hemisphere
Severe midlatitude climates have long, cold winters and short summers, and have large annual temperature ranges
Polar climates receive little insolation and are permanently cold and dry
Highland climates depend on elevation of mountainous terrain for their climate characteristics
Many paleoclimatology methods are used to understand the Earth’s past climate
There are several factors that influence long-term climate change
Global warming is related to the increase in carbon dioxide release by humans