Climate%20and%20Ecosystems

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Climate and Ecosystems

• Chapter 11

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• Weve talked about Global Climate Change
  (sometimes called Global Warming).
• What is climate?
• What effects can a changing climate have on
  living organisms?
• Suppose your region has an especially hot summer,
  followed by a very cold winter that includes a
  snowstorm. Does this support, disprove, or have
  little to do with Global Climate Change?

D A I L Y W O R K
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Climate

• Climate is not the same thing as weather!
• Climate consists of the prevailing weather
  patterns in a region over longs periods of time.
• Climate is caused by many factors, including
  location on the globe, nearness to an ocean, wind
  direction, geography.

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True or False Summer is warmer than winter
because the earth is closer to the sun in the
summer.

1. True
2. False

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True or false When it is winter in the northern
hemisphere, it is summer in the southern
hemisphere.

1. True
2. False

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Think about this

• If it were true that seasons were caused by the
  earth being closer to or further away from the
  sun
• how would it be possible that the southern
  hemisphere is experiencing summer while the
  northern hemisphere is experiencing winter?
• Remember, we are 93 million miles from the sun.
  Small changes in distance arent going to have a
  big effect.

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The sun drives climate as well as the seasons.
Summer in the Northern Hemisphere
North Pole
90 N
23.5 tilt
0
equator
0
23.5 tilt
Summer in the Southern Hemisphere
90 S
South Pole
December 21st northern winter solstice
southern summer solstice
June 21st northern summer solstice
southern winter solstice
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• Average temperature at any part of the globe is
  affected not by how close we are to the sun (a
  common misconception) but by the angle of
  incidence of the suns rays.

Less direct rays less solar energy cooler
region
More direct rays more solar energy warmer
region
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• Global air circulation influences local climates.
• Rising air cools and drops moisture.
• Descending air tends to be dry.

cold, dry air falls
cool, moist air rises (rain/snow)
Polar Easterlies
90 N polar cap
60 N
Westerlies
warm, dry air falls
30 N
desert
N.E. Tradewinds
hot, moist air rises (rain)
rain forest
rotation
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S.E. Tradewinds
rain forest
desert
30 S
warm, dry air falls
Westerlies
60 S
Polar Easterlies
polar cap 90 S
cool, moist air rises (rain/snow)
cold, dry air falls
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• According to this diagram, where on the planet
  should we find
• Deserts?
• Tropical rain forests?
• Permanent snowfields?

A. Cool, moist, rising air
D A I L Y W O R K
B. Warm, dry, falling air
C. Warm, moist, rising air
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• Ocean current also affects climate.
• Water tends to absorb and retain heat, and lose
  it slowly.
• Ocean water near the equator tends to be warm, so
  currents from the equator are warm.
• Water near the poles is much cooler.

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• The Gulf Stream carries warm water from the
  equator northward, warming the coast of Europe.
• There is evidence that the Greenland ice is
  melting, due to Global Climate Change, and
  pouring cold water into the North Atlantic. If
  enough cold water is dumped into the Atlantic, it
  could divert the Gulf Stream.

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If the Greenland ice melts and disrupts the Gulf
Stream, what will happen to the climate of
Northern Europe?

1. It will get much colder.
2. It will get much warmer.
3. There will be very little change.

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• Observe this diagram of the Jet Stream,
  prevailing winds across the North American
  Continent.
• Remembering that oceans tend to absorb more heat
  than land, and that currents and wind pattern
  affect climate, explain the pattern of climate
  across North America as shown by the map of USDA
  planting zones in the next slide.

D A I L Y W O R K
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Climate Fluctuations

• Some natural processes can cause local climate to
  fluctuate from year to year.
• One example El Niño/ La Niña weather cycles
  along the American Pacific coasts.

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More info at http//www.sbg.ac.at/ipk/avstudio/pi
erofun/atmo/elnino.htm
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In an El Niño cycle, prevailing Trade Winds
weaken. Warm water spreads back across the
Pacific, disrupting upwellings along the South
American coast.
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As a result of El Niño, what happens to the
fishing industry off of the coast of Peru?

1. Warmer water increases the nutrients and the
   number of fish.
2. Loss of cold upwellings decreases nutrients and
   the number of fish.
3. There is no change to the fishing industry this
   is just part of the weather cycle.

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Local Climate

• Localized climate zones can be caused by
• Proximity to oceans or large lakes.
• Position of mountain ranges.
• Wind direction.

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Oregon Coast
Peruvian Coast
Oregon is on the west side of the North American
continent. Peru is on the west side of the South
American continent. Why do these two areas look
so different?
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Water is released as air rises and cools.
Dry air sinks, warms and absorbs water from the
land.
Water is carried from ocean by prevailing winds.
dry climate in rain shadow
moist climate
The rain shadow effect can cause moist conditions
on one side of a mountain range and dryer
conditions on the opposite side of the
mountains. On the Peruvian coast, prevailing
winds blow from the mountains toward the ocean.
What effect might that have on climate on the
coast of Peru?
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Lake Effect
Lakes, too, can influence local climate if they
are large enough.
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high
rock, snow, ice
tundra
coniferous forest
deciduous forest
altitude
tropical forest
low
equator (0)
poles (90)
latitude
Altitude and latitude also interact to create
local climates that support different types of
communities.
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• Observe the map of Oregon on the next slide. Use
  what you have learned to explain the average
  rainfall in the different areas of the state
  indicated on the map.

D A I L Y W O R K
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Coastal Mountains
Cascade Mountains
D A I L Y W O R K
Pacific Ocean
Oregon Coast 70-100 inches
Willamette Valley 25-30 inches
Eastern Oregon 6 8 inches
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If the prevailing winds in Oregon blew from east
to west, what would our coastline be like?

1. Rainy, as it is now.
2. Dry, like Peru.
3. A mixture of dry and wet areas, depending on the
   local terrain.

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• The prevailing winds blow from west to east on
  the North American continent. Why is the east
  coast of the U.S. NOT a dry desert like Peru?

D A I L Y W O R K
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Recap

• Climate begins with the suns heat.
• Climate is influenced by ocean and atmospheric
  currents, which are driven by the suns heat.
• Geography influences local climate.
• Climate directly affects what organisms can live
  in an area.