The document discusses climate classification and climate change. It describes the six primary climate groups classified by the Köppen system based on temperature and precipitation. These include tropical humid climates, dry climates, mild midlatitude climates, severe midlatitude climates, polar climates, and highland climates. Paleoclimatology methods are used to study past climate changes. Factors influencing long-term climate change include greenhouse gases, solar output, and ocean currents. Evidence suggests the Earth is currently undergoing global warming due to increased carbon dioxide from human activities.

1. © 2011 Pearson Education, Inc.
Chapter 8: Climate and
Climate Change
McKnight’s Physical Geography:
A Landscape Appreciation,
Tenth Edition, Hess

2. © 2011 Pearson Education, Inc.
Climate and Climate Change
2
• Climate Classification
• World Distribution of Major Climate Types
• Global Patterns Idealized
• Global Climate Change

3. © 2011 Pearson Education, Inc.
Climate Classification
• Need a consistent climate
classification scheme to
understand numerous climate
regions
• Earliest known scheme was
by the ancient Greeks 2200
years ago
• Classified three major climate
regions
3
Figure 8-1

4. © 2011 Pearson Education, Inc.
Climate Classification
• Köppen climate classification system
• Based on a database of annual and monthly average
temperature and precipitation
• Four of five major groups classified by temperature
• Fifth group classified by precipitation
• Subdivided the five groups further based on
temperature and precipitation relationships
• Köppen letter code system
– Three letters; first describes group, second describes
precipitation, third describes temperature
• Climographs
4

5. © 2011 Pearson Education, Inc.
Climate Classification
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Figure 8-2
• The modified Köppen classification system

6. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
6
Figure 8-11
• Weather records. How do we explain their locations?

7. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Tropical Humid Climates
(Group A—Figure 8-5)
– Molded by the tropical
latitudinal regions
– Winterless climates; little
temperature change
– Moisture is prevalent
– Precipitation influenced
by ITCZ
– Three subtypes
7
Figure 8-5

8. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Tropical wet climate (Af)
– Equatorial
– Monotonous climate
– Daily temperature range
exceeds annual range
– High humidity
– Rainfall multiple times a
day
– High solar angle year
round; ITCZ influences
rainfall
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Figure 8-6b
Figure 8-6a

9. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Tropical savannah
climate (Aw)
– Lies north and south of
Af climates
– Seasonal alteration of
wet and dry periods due
to position changes of
ITCZ
– Smallest rainfall
amounts of tropical
regions
9
Figure 8-8b
Figure 8-8a

10. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Tropical monsoonal
climate (Am)
– Regions with prominent
monsoonal wind pattern
– Extensive rainfall during
high-Sun season
– Cherrapunji, India
averages 425 inches
– Cloud cover reduces
temperatures slightly in
summer versus spring
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Figure 8-10b
Figure 8-10a

11. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Dry climates (Group B –
Figure 8-12)
– Cover about 30% of
land area worldwide
– Lack of uplift or lack of
moisture
– Typical in subtropics
– Marine deserts
– Two main types, two
subtypes
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Figure 8-12

12. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Subtropical desert climate
(BWh)
– Lie near subtropical highs
– Precipitation is scarce
(rare) and unreliable
(highly variable)
– Precipitation that does
form is short lived and
intense
– Hot temperatures
– Large diurnal range of
temperature
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Figure 8-14b
Figure 8-14a

13. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Subtropical steppe climate
(BSh)
– Typically surrounds BWh
climates
– Separate desert climate
from humid climate
– Extremes are muted in
steppe regions
• Cooler temperatures
• More rainfall
– Seasonal concentration
of rainfall
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Figure 8-17

14. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Midlatitude desert climate
(BWk)
– Far removed from oceanic
influence
– Meager and erratic
precipitation
– Most precipitation occurs
in summer
– Cold winters, overall
cooler temperatures
– Greater annual
temperature range
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Figure 8-18a
Figure 8-18b

15. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Midlatitude steppe climate
(BSk)
– Occupies transitions
between desert and
humid climates
– Greater precipitation than
midlatitude deserts
– Less temperature
extremes than midlatitude
deserts
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Figure 8-19

16. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Mild Midlatitude Climates
(Group C—Figure 8-20
– Transition between
warmer tropical climates
and colder severe
midlatitude climates
– Hot summers, mild
winters
– Highly variable
precipitation amounts
– Three primary groups
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Figure 8-20

17. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Mediterranean Climate
(Csa, Csb)
– Modest annual
precipitation in winter,
summer is virtually rainless
– Mild winters and hot
summers
– Clear skies especially in
summer
– Most is Csa (hot
summers); Csb climates
have mild summers and
are more coastal 17
Figure 8-21a
Figure 8-21b

18. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Humid Subtropical Climate
(Cfa, Cwa)
– Warm to hot summers;
high humidity (Cfa days are
hot and sultry)
– Precipitation reaches
summer maximum, some
drop off for winter
– Winter temperatures in Cfa
regions are mild; typically
cooler than mediterranean
climates
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Figure 8-24a
Figure 8-24b

19. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Marine West Coast Climate
(Cfb, Cfc)
– Influenced by onshore flow
from midlatitude westerlies
– Occurs when no topographic
boundaries inhibit flow of
maritime air inland
– Frequently cloudy with
precipitation
– Temperate climate
– Wettest of the midlatitudes
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Figure 8-26a
Figure 8-26b

20. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Severe Midlatitude
Climates (Group D)
– Only in Northern
Hemisphere
– Continentality—
remoteness from oceans
– Four recognizable
seasons; long, cold winter
and short summer
– Subdivided into two types
based on temperature
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Figure 8-27

21. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Humid Continental Climate
(Dfa, Dfb, Dwa, Dwb)
– Dominated by westerlies and
associated frequent weather
changes
– Warm summers, cold winters
– Generally low precipitation;
higher amounts near coasts
– Winter precipitation
associated with cyclones;
summer with convection
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Figure 8-28a
Figure 8-28b

22. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Subarctic Climate (Dfc, Dfd,
Dwc, Dwd)
– Winters are long, dark, and
bitterly cold
– Summers are short; spring
and fall pass quickly
– Coldest temperatures; little
precipitation
– Largest annual temperature
ranges (i.e., -90 °F to 98 °F
in Verhoyansk, Siberia)
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Figure 8-31a
Figure 8-31b

23. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Polar Climates (Group E)
– Receive little insolation
– No average temperature
above 50 °F
– Extremely dry, but
classified as nonarid
– Two primary groups
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Figure 8-27

24. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Tundra Climate (ET)
– Southern boundary the
“treeline”
– Northern boundary border
of any plant cover
– Long, dark winters
– Brief, cool summers
– Little precipitation
– Winters not as severely
cold as subarctic climate
region
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Figure 8-33a
Figure 8-33b

25. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Ice Cap Climate (EF)
– Mainly Greenland and
most of Antarctica
– Permanent cover of ice
and snow
– Ice plateaus; high latitude
with high altitude
– Very limited precipitation,
essentially polar deserts
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Figure 8-34a
Figure 8-34b

26. © 2011 Pearson Education, Inc.
World Distribution of Major
Climate Types
• Highland Climate
(Group H)
– Nearly infinite variations
from place to place
– Altitude more significant
than latitude in highlands
– Exposure (whether a
slope is windward or
leeward)
– High diurnal temperature
variations due to thin, dry
air
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Figure 8-36

27. © 2011 Pearson Education, Inc.
Global Patterns Idealized
• Presumed arrangement of Köppen climate types on a
hypothetical continent (Figure 8-40)
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Figure 8-40

28. © 2011 Pearson Education, Inc.
Global Climate Change
• Changes in climate on long time scales
• Weather is noise, climate is long-term signal
• Episodic events (i.e., El Niño and the PDO) versus
long-term global climate change
• Numerous time scales to consider (i.e., temperature)
– 70 million years, clear global cooling trend
– 150,000 years, temperature fluctuated
– 10,000 years, sharp warmup
– 150 years, warming trend relative to last 1000 years
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29. © 2011 Pearson Education, Inc.
Global Climate Change
• Paleoclimatology
– Proxy measures of
climate (i.e., ice cores,
tree rings)
• Dendrochronology—
study of past climate
through tree ring analysis
• Oxygen isotope analysis
– Lighter versus heavier
isotopes
– High 18
O/16
O ratio,
glaciation
29
Figure 8-41

30. © 2011 Pearson Education, Inc.
Global Climate Change
• Coral reefs
– Ratio of 18
O/16
O in coral reefs
– Height of old reefs
• Ice cores
– Ratio of 18
O/16
O serves as a
thermometer
– Provide direct atmospheric
composition measurements
• Pollen data
– Radiocarbon dating
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Figure 8-42

31. © 2011 Pearson Education, Inc.
Global Climate Change
• Causes of Long-Term
Climate Change
– Atmospheric aerosols
• Large quantities of aerosols
can block insolation and lower
temperature
• Result from volcanic
eruptions or asteroid impacts
• Anthropogenic impacts
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Figure 8-43

32. © 2011 Pearson Education, Inc.
Global Climate Change
• Climate change causes (cont.)
– Solar output fluctuations
• Sunspot activity related to solar
output
– Variations in Earth-Sun
relations
• Shape of Earth’s orbit
• Inclination of Earth’s axis
• Precession of Earth’s axis
• Milankovitch cycles
32
Figure 8-44

33. © 2011 Pearson Education, Inc.
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
• Water vapor feedback challenges
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34. © 2011 Pearson Education, Inc.
Global Climate Change
• Climate change causes (cont.)
– Roles of the oceans
• Absorb large amounts of carbon
• Methane hydrates
• Heat transfer from low latitudes
to high latitudes
• Climate models
– General circulation models
(GCMs)
– Numerous assumptions
– Accuracy of the models
34
Figure 8-45

35. © 2011 Pearson Education, Inc.
Global Climate Change
• Evidence of current global
warming
– 11 of 12 warmest years on
record occurred between 1995–
2006
– Global temperature increasing at
0.13 °C per decade
– Ocean temperatures increasing
to depths of 9800 feet
– Sea level rise
– Temperatures in Arctic increasing
at twice global rate
35
Figure 8-46a

36. © 2011 Pearson Education, Inc.
Global Climate Change
• Evidence of current global
warming (cont.)
– Sea ice in Arctic decreasing by
7.4 percent per decade
– Ice caps and glacier melt leading
to sea level rise
– Temperatures on top of a
permafrost layer have increased
by 5.4 °F
– Number of intense tropical
cyclones increased since 1970
– Amount of water vapor in
atmosphere increased
– Changes in precipitation amounts
36
Figure 8-46b

37. © 2011 Pearson Education, Inc.
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
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38. © 2011 Pearson Education, Inc.
Global Climate Change
• Consequences of global
warming
– Projected climate in the
upcoming century
• Climate will warm at about 0.4 °F
per decade
• Changes will be greater than
those observed during 20th
century
• Estimated increase of
temperature from 3.3 °F to 7.2 °F
• Sea level rise
• Stronger tropical cyclones
• Increased precipitation
38
Figure 8-47a

39. © 2011 Pearson Education, Inc.
Global Climate Change
• Addressing global warming
– Kyoto protocol
– Standards for newly
industrialized countries
– Mitigating and adapting
39
Figure 8-47b

40. © 2011 Pearson Education, Inc.
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
40

41. © 2011 Pearson Education, Inc.
Summary
• Mild midlatitude climates typically have long and hot
summers and 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
41

42. © 2011 Pearson Education, Inc.
Summary
• 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
42