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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?

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