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14.3-14.4 Climatic Changes
Causes of Climate � Latitude – differential heating � Topographic effects –
� Proximity to water � Altitude � Mountain range
� Air Masses
14.3 - Climatic Changes � Climate change is a slow process but has
occurred multiple times in earth’s history � Ex) Multiple ice ages – periods of cooler
climate and extensive glaciers
Short-term climatic changes � Ice ages are an example of long-term
climate change � Seasons- an example of short-term
climate change
Seasons � What causes them?
� The tilt of the earth on its axis. Seasons are NOT caused by distance from the sun.
The hemisphere tilted toward the sun receives more direct radiation. How does this affect intensity?
El Nino � Climate changes due to reversing of an
ocean current in the Pacific Ocean. � Basically, El Nino can flip climate
conditions in many areas.
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Natural Climate Change � Climate changes have occurred
throughout earth’s history � Can be caused by changes in solar
activity, earth’s tilt, and volcanic eruptions
1. Solar activity � Relationship between low sunspot activity
and colder climates on earth. � Maunder Minimum – low sunspot activity
period
2a. Earth’s orbit � Earth’s orbit cycles between circular and
elliptical every 100,000 years. � A more elliptical orbit = warmer climate
because earth is closer to the sun.
2b. Earth’s tilt � Currently the earth has a 23.5 degree tilt
on its axis. Seasons are caused by the tilt changing throughout the year.
� The angle varies from 22.1º to 24.5º every 41,000 years.
� Less angle = seasons not as drastic
3. Earth’s wobble � The axis of the earth points to a different
point every 14000 years. � Switches cause summer and winter to be
more drastic.
4. Volcanic activity � Big eruptions send a massive amount of
dust in the atmosphere. It can remain suspended for years blocking solar radiation.
� Cause cooler climate periods � Short term climate change
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14.4 - Human Factor � Greenhouse effect – natural heating of
earth’s surface caused by certain atmospheric gases (water vapor, carbon dioxide).
� The gases trap heat that is radiated by the earth.
� It is NOT a human invention.
Greenhouse effect � It may be possible to increase or
decrease the greenhouse effect by changing the amount of greenhouse gases (CO2)
� This is the current controversy
Global Warming � Temps have warmed over the last 200 yrs
(scientists agree) � Could eventually cause ice caps to melt,
coastal flooding, deserts to spread, and more severe storms
Global Warming, pg 376!!! � Scientists agree that temps are climbing � Do not all agree about why � Natural causes vs. increased CO2 in the
atmosphere (artificial or human influences)
Increase of carbon dioxide � Burning of fossil fuels � Deforestation
� Don’t waste electricity! Recycle!
Renewable vs. Nonrenewable � Renewable energy sources – energy from
resources that are continually replenished � Examples? � Nonrenewable energy sources – take
thousands of years to form. Cannot be replaced as quickly as they are used
� Examples? � Compare and contrast benefits?