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)

Microthermal Climates Humid Continental Hot-Summer Climates Dfa, Dwa Humid Continental Mild-Summer Climates Dfb, Dwb Subarctic Climates Subarctic 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”) EM More 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 10 Climate Change Geosystems 6e An Introduction to Physical Geography Robert W. Christopherson Charles E. Thomsen

Causes of Climate Change Variations in the Earth’s orbital characteristics Atmospheric carbon dioxide variations Volcanic eruptions Variations in solar output Humans

Greenhouse Gases Human 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 Dioxide Atmospheric CO 2 levels began rising during the Industrial Revolution Tremendous fossil fuel burning and heavy deforestation increased CO 2 levels – this trend continues CO 2 is responsible for 64% of global warming

Carbon Dioxide Sources

What are the Fossil Fuels?

Carbon Dioxide Sources

Methane Methane currently increasing faster than CO 2 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 (CH 4 )

Volcanic Eruptions Sulfur 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 ° C Sunspots Huge magnetic storms Seen as dark (cooler) areas on the sun's surface. Cycle every 11, 90, and 180 years

GCM Predictions Crop patterns and natural plant/animal habitats will shift to maintain preferred temperatures During this century, climate regions could shift miles poleward Soil moisture projected to decrease in midlatitudes

GCM Predictions Forest cover will undergo major species disturbances Expansion of zones affected by tropical diseases Alpine glaciers

Global Temperatures Figure Low point: 1884 = -0.7 High point: 1998 = °C = 2.5°F

Temperature Anomalies for 2003 Figure 10.28

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

Sea Level Rise During the 20 th century, sea level rose 4-8 inches Could rise 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 Shelves In 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 Climates Changes 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 10 Climate Change Geosystems 6e An Introduction to Physical Geography Robert W. Christopherson Charlie Thomsen