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 22ºCw = 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, DwcSubarctic 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 climatesExtremely cold temperatures in winter primarily due to:

continental locations = Siberian High in winterhigher latitudescP 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 climateLow annual range of temperatureExists only along very fringes of highest latitudesBering 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 characteristicsAtmospheric carbon dioxide variationsVolcanic eruptions Variations in solar outputHumans

Greenhouse GasesHuman activities are enhancing the Earth’s natural greenhouse effectCarbon dioxide, methane, nitrous oxide, CFCs, and water vaporGreenhouse gases are transparent to sunlight but opaque to longwave radiation

Carbon DioxideAtmospheric CO2 levels began rising during the Industrial RevolutionTremendous fossil fuel burning and heavy deforestation increased CO2 levels – this trend continuesCO2 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 methaneMethane 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 hazeCombined with ejected particulate matterOne 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 OutputClimate 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° CSunspots

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 temperaturesDuring this century, climate regions could shift 90-350 miles polewardSoil moisture projected to decrease in midlatitudes

GCM PredictionsForest cover will undergo major species disturbancesExpansion of zones affected by tropical diseasesAlpine 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 inchesCould rise 3.5-34.7 inches this centuryThermal expansion of water will increase sea level riseHigher 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 yearsWarmer ocean and air temperatures are melting shelves on both sidesClear evidence of changes in Earth’s energy balance

Antarctic Ice Disintegration

Figure 10.32

Arctic ClimatesChanges in ocean temperatures could alter global temperaturesArctic region warmed 9°F since 1987This has led to a freshening of northern oceansGreenland ice melting at 1m/yearPermafrost is meltingIncreased precipitation in Arctic/Antarctic areas

End of Chapter 10Climate Change

Geosystems 6eAn Introduction to Physical Geography

Robert W. ChristophersonCharlie Thomsen