Mesothermal Climates (C)  Humid Subtropical (Hot-Summer) Climates (Cfa)  

Humid Subtropical (Winter-Dry) Climates (Cwa)

Marine West Coast Climates (Cfb, Cfc)  

Mediterranean Dry-Summer Climates (Csa, Csb)  

Humid Subtropical (Winter-Dry) Climates (Cwa) C = warmest month above 10ºC, coldest month above -3ºC = seasonal climates

a = hot summer, warmest month above 22ºC

w = winter dry (> 70% of rainfall concentrated in summer months)

Mesothermal Climates (C)  

Mesothermal Climates (C)  

Microthermal ClimatesHumid Continental Hot-Summer Climates

Dfa, Dwa

Humid Continental Mild-Summer ClimatesDfb, Dwb

Subarctic ClimatesSubarctic Cool-Summer: Dfc, Dwc

Subarctic Extreme-Winter: Dfd, Dwd

Microthermal Climates (D)Subarctic Climates (Dfc, Dwc, Dwd)

Found poleward of Dfb and Dwb climate.

Extensive geographically:

North America, stretching from Atlantic to Pacific.

Eurasia, stretching from Scandinavia to the Pacific.

Subarctic extreme-winter found only in eastern Asia

Most extreme temperature ranges of all climates

Extremely cold temperatures in winter primarily due to:

continental locations = Siberian High in winter

higher latitudes

cP air masses

Microthermal Climates (D)

Polar and Highland Climates

Tundra Climate (ET)

Ice Cap and Ice Sheet Climates (EF)

Polar Marine Climate (aka “Polar Maritime”) EMMore moderate than other two polar climates (why?)

No month below -7°C (20°F), but not as warm as tundra climate

Low annual range of temperature

Exists only along very fringes of highest latitudes

Bering Sea (Alaska, Russia), southern Greenland, northern Iceland, Norway)

Polar and Highland Climates

Chapter 10Climate Change

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharles E. Thomsen

Causes of Climate ChangeVariations in the Earth’s orbital characteristics

Atmospheric carbon dioxide variations

Volcanic eruptions

Variations in solar output

Humans

Greenhouse GasesHuman activities are enhancing the Earth’s natural greenhouse effect

Carbon dioxide, methane, nitrous oxide, CFCs, and water vapor

Greenhouse gases are transparent to sunlight but opaque to longwave radiation

Carbon DioxideAtmospheric CO2 levels began rising during the Industrial Revolution

Tremendous fossil fuel burning and heavy deforestation increased CO2 levels – this trend continues

CO2 is responsible for 64% of global warming

Carbon Dioxide Sources

What are the Fossil Fuels?

Carbon Dioxide Sources

MethaneMethane currently increasing faster than CO2 in the atmosphere

19% of total atmospheric warming attributed to methane

Methane generated by rotting vegetation, digestion in cattle and termites, burning of vegetation, and melting permafrost

Methane (CH4)

Volcanic EruptionsSulfur dioxide reacts with water vapor causing haze

Combined with ejected particulate matter

One of the coldest years in the last two centuries was 1816, the “Year Without a Summer”

Caused by eruption of Tambora in 1815

Temperatures can decrease after eruptions for up to 3 years

Mount St. Helens

Variations in Solar Output

Climate models predict that a change in solar output of only 1 percent per century alters the Earth’s average temperature by 0.5 -1.0° C

Sunspots

Huge magnetic storms

Seen as dark (cooler) areas

on the sun's surface.

Cycle every 11, 90, and

180 years

GCM PredictionsCrop patterns and natural plant/animal habitats will shift to maintain preferred temperatures

During this century, climate regions could shift 90-350 miles poleward

Soil moisture projected to decrease in midlatitudes

GCM PredictionsForest cover will undergo major species disturbances

Expansion of zones affected by tropical diseases

Alpine glaciers

Global Temperatures

Figure 10.28

Low point: 1884 = -0.7

High point: 1998 = +0.7

1.4°C = 2.5°F

Temperature Anomalies for 2003

Figure 10.28

Sea Level IssuesDuring this century, global warming will cause sea levels to rise at least 1.5 meters (about 4.5 feet).

Sea Level RiseDuring the 20th century, sea level rose 4-8 inches

Could rise 3.5-34.7 inches this century

Thermal expansion of water will increase sea level rise

Higher sea levels = destruction of small island nations, river deltas, lowland coastal farming, barrier islands

July 2029 Temperature Forecast

Figure 10.31

Disintegration of Ice ShelvesIn 2002, Larsen-B ice shelve collapsed in 35 days after existing for 11,000 years

Warmer ocean and air temperatures are melting shelves on both sides

Clear evidence of changes in Earth’s energy balance

Antarctic Ice Disintegration

Figure 10.32

Arctic ClimatesChanges in ocean temperatures could alter global temperatures

Arctic region warmed 9°F since 1987

This has led to a freshening of northern oceans

Greenland ice melting at 1m/year

Permafrost is melting

Increased precipitation in Arctic/Antarctic areas

End of Chapter 10Climate Change

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharlie Thomsen