changes in solar radiation are primary cause for climates to change ~10% change in solar radiation...
TRANSCRIPT
Changes in solar radiation are primary cause for climates to change
~10% change in solar radiation output can dramatically alter Earth’s climate
Changes in solar radiation are primary cause for climates to change
~10% change in solar radiation output can dramatically alter Earth’s climate
Chapter 15 - Climate changes
Longer term changes in total output
•Milankovitch type variationsShorter term
•Sunspot activity (?), Human intervention
Longer term changes in total output
•Milankovitch type variationsShorter term
•Sunspot activity (?), Human intervention
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Short term cyclic•semi-cyclic in nature are Sunspots
•Cooler areas on the Sun’s photosphere
•Magnetic anomalies that trigger cooler conditions•Less than 0.01% change in energy
Short term cyclic•semi-cyclic in nature are Sunspots
•Cooler areas on the Sun’s photosphere
•Magnetic anomalies that trigger cooler conditions•Less than 0.01% change in energy
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Linkage between # of sunspots and mean sea surface temp (a function of global temp).
Non-cyclic short term--dust in atmospheremany causes
volcanic explosionsdroughtsmeteorite impactshumans
Example-1815 Mt. Tambora eruption in the East Indies created a year without a summer due to dust blocking sunlight
Non-cyclic short term--dust in atmospheremany causes
volcanic explosionsdroughtsmeteorite impactshumans
Example-1815 Mt. Tambora eruption in the East Indies created a year without a summer due to dust blocking sunlight
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Drought and desertification
can create either a negative or positive feedback loop
drought triggers dust
dust decreases temp
temp decrease may trigger rain or or may further the drought
Drought and desertification
can create either a negative or positive feedback loop
drought triggers dust
dust decreases temp
temp decrease may trigger rain or or may further the drought
Dust storm in Sahara
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Land use changes in Albedo
different materials covering the land surface reflect solar radiation differently
e.g., trees vs grass vs crops
concrete vs blacktop, vs gravel
Results in an Urban “Heat Island” or “Heat Bubble” effect surrounding cities
Often cooler temps in agricultural vs city
Often cooler temps in forest vs agricultural
Land use changes in Albedo
different materials covering the land surface reflect solar radiation differently
e.g., trees vs grass vs crops
concrete vs blacktop, vs gravel
Results in an Urban “Heat Island” or “Heat Bubble” effect surrounding cities
Often cooler temps in agricultural vs city
Often cooler temps in forest vs agricultural
Changes in Albedo
Savanna to desert
1.8% of earth’s surface
16-36% change
Temperate forest to field, grassland
1.6% of earth’s surface
12-15% change
Tropical forest to field, savanna
1.4% of earth’s surface
7-16% change
Salinization, field to salt flat
0.1% of earth’s surface
1-25% change
Milankovitch cycles
small changes in Earths orbit around the sun and variability in its axis of rotation
•Eccentricity - ellipicity of annual orbit
•Obliquity - changes in tilt of Earth’s axis
•Precession - change in position of earth along the annual orbit with respect to when the northern hemisphere is tilted toward the sun
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Artists rendition of Chicxulub impact at time of impactArtists rendition of Chicxulub impact at time of impact
Plate tectonics
Changes in location of continents affects global energy movement and absorption
Influences position of and strength of oceanic currents
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Plate tectonics - impact on continental location with respect to latitude and oceanic currents with respect to continuity of motion
Plate tectonics - impact on continental location with respect to latitude and oceanic currents with respect to continuity of motion
Changes in ocean currents
Modern examples of El Nino and la Nina triggered widespread interest in this area
Showed how important ocean currents are in relation to global, regional, and local climates
•global - El Nino-La Nina
•regional - coastal desert in Peru
•local - cooler temps along the Texas Gulf coast due to proximity to water and sea-land breeze
Volcanic ash plume from Mont Serrat
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Ash from Mt St Helens
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Before- 1964
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After- 1990
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Thematic mapper satellite image of Buffalo County, NebraskaThematic mapper satellite image of Buffalo County, Nebraska
Greenhouse and other gases influencing climate changeGreenhouse and other gases influencing climate change
Non-anthropogenic sources of green house gases
Volcanic activity
•CO2; S02; H20;
Biological decay
•CH4 - Methane
Non-anthropogenic sources of green house gases
Volcanic activity
•CO2; S02; H20;
Biological decay
•CH4 - Methane
