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Climate Change
November 4, 2014
Global Climate Change
• Global Warming – describes a rapid increase in the
temperature of Earth’s surface, water, and atmosphere,
which is causing changing in most natural systems (such as
seasons and life cycles)
Global Temp Change since 1880
Causes of Climate Change
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Variations in the Earth’s orbital characteristics
Atmospheric variations in greenhouse gases
Volcanic eruptions
Variations in solar output
Landforms
Variations in the Earth’s orbital
characteristics
• The Milankovitch theory
– Cyclical variations in three of the Earth’s
orbital characteristics
• Eccentricity
• Rotation
• Tilt
– Vary the amount of solar radiation that
reaches the Earth’s surface
Milankovitch Cycles
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Carbon Cycle
Greenhouse Effect
Carbon Dioxide Sources
What are the Fossil Fuels?
Greenhouse Gas-Temp Correlation from Ice Cores
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 0.5°C (32.9°F) ̶ 1.0°C (33.8°F)
Sea Level Rise
Arctic Sea Ice Changes 2012
GCM Predictions
• Crop 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
• Forest cover will undergo major species disturbances
• Expansion of zones affected by tropical diseases
• Alpine glaciers
Reconstructing Climate Change
• Prior to recorded data, use Proxy Data:
– Palynology - pollen in lake sediments shows
veg type - > 15,000 year record
– Dendrochronology - tree rings show growth
patterns – 9000-yr record
– Ice Cores – air trapped over 650K yrs shows
past CO2 concentrations
Proxy Data
• Measures cause and effect relationships
indirectly
• Paleoclimatology – science that studies past
climates using proxy data
• Proxy data – ice cores, sediments, coral reefs,
ancient pollen, tree-rings
• Antarctic ice cores have climate reconstructed
back 740,000 years
• Air bubble in ice allow the reconstruction of
atmospheric methane levels
Tree-Ring Records
Tree-Ring Records
Palynology
Ocean Core Records