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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
Chapter 19
“Ecosystem Essentials”
Geosystems 6eAn Introduction to Physical Geography
Robert W. ChristophersonCharles E. Thomsen
Ecology
Study of relationships between organisms and their abiotic environment
Can be studies at several levels:Population
Community
Ecosystem
Biosphere
Fig 1.8
Communities
Fig. 19.3
Community TermsHabitat
Type of environment where an organism resides
NicheFunction of a life form within a community
In stable community, no niche is left unfilled
Competitive Exclusion Principle applies:No two species occupy same niche at same time
Interactions in communitiesCompetition
Negative for both species (–/–)
Symbiotic/Mutualistic (+/+)Both species benefitlichen (fungi and algae)
Predation and Parasitic (+/–)One benefits, one loses