Transcript Next lecture: Humans, Climate Change, and Ecological Responses

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Next lecture: Humans, Climate Change,
and Ecological Responses
Assignment
•Climate Change Lecture Outline
(read only; no textbook)
•IPCC Report: Print, Read, Bring to lecture:
Group member:
1: pg. 2-5; 12-16
2: pg. 5-9; 12-16
3: pg.10-16
•Be prepared to summarize your part to rest
of group.
•Midwest Climate
Ch 4 Variation in the Physical Environment
OBJECTIVES: What creates variation
in climate and how does it explain the
diversity and distribution of biomes?
•
•
•
•
•
Build a model for proximal causes
of global variation in climate and
biomes
How do features of the earth
contribute to climatic variation?
What are causes of temporal
changes in climate and biomes?
What are local effects on climate?
***What are 5 features of
earth that affect climate?
***PRE-TEST: What feature of the earth causes:
1)
2)
3)
4)
Daily rhythm of dark and light?
Temperature warmer at 0º than 90 º?
Seasonal change in climate?
Less variation in temperature in
N than S?
5) Winds to be diverted from N-S direction?
A) Rotates on axis
B) Round
C) Tilt of 23º on axis
D) Rotates around sun
E) More land mass in N than S
Answers:
1)
2)
3)
4)
Daily rhythm of dark and light? = A
Temperature warmer at 0º than 90 º? = B
Seasonal change in climate? = C + D
Less variation in temperature in
N than S? = E
5) Winds to be diverted from N-S direction?
=A+B
A) Rotates on axis
B) Round
C) Tilt of 23º on axis
D) Rotates around sun
E) More land mass in N than S
Overall conceptual model:
• Solar radiation 
• temperature 
•
wind and ocean currents 
•
precipitation
***Why does temperature decline at higher
latitudes?
***What accounts for differences in range of
temperatures in N vs S hemisphere?
N.B. Specific heat is higher for water than land.
***What causes seasons and temporal
variation in temperature?
•Variation in temperature generates winds.
(N.B. Mirrror of S and N hemispheres)
•Winds drive ocean currents and redistribute
heat and moisture.
***What are latitudes of tropical rainforests
and deserts? Why?
Why is it wet at 0° and dry at 30°?Hadley
cells and ITCZ (inter-tropical convergence
zone):
Solar equator (ITCZ) moves seasonally.
• (so do belts of temp., wind, and rain)--->
• causes seasonal variation in climate.
What causes deflections in air flow from
N-S? Coreolis effect ; affects oceans too!
Ocean currents 1) differ in N and S, 2)
redistribute heat and moisture and 3) affect
• marine environment on global scale
• climates on land.
clockwise
counterclockwise
upwelling
Upwelling currents bring cold, nutrientrich water to the surface --->
support high productivity.
***Why are (most) deserts on W side of
continents?
What causes the Gobi desert in central Asia?
Why does England have temperature
deciduous forest rather than boreal forest?
Overall conceptual model:
Solar radiation 
• temperature 
•
wind and ocean currents 
•
precipitation
***What factors have changed
existence and location of biomes
through time?
•
•
•
•
•
•
•
Continental drift
Mountain building and rain shadows
Changes in orbit, tilt, wobble of earth
Climate variation
past climate change
present climate change
Human alteration in land cover
Changes in biomes
through geological
time…
El Nino vs. El Nina: note recent increase
in stength + frequency of El Nino
La Nina…
World-wide variation in effects of El Nino on
climate
El Nino years bring drought and fire to tropical
peat forests in SE Asia
Negative impact of
El Nino on crops
In far-flung places
***What determines local climate?
• 1) Proximity to bodies of water
•
Continental climates in interiors
More arid
More variable
•
Maritime climates on coasts
Less arid
Less variable
2) Topography: gradients in mountains
• Air cools as rises---> temp. decrease-->vegetation changes
• (6-10°C drop for every 1000 m in elevation)
Why do mountains cause a rainshadow on
their leeward side? How do they affect
biomes?
How do mountain and wind directions affect this?
***Topography superimposes local
variation on general climatic patterns.
What causes these vegetation patterns?
Higher temperatures on S than N-facing
slopes; >T --> > evaporation + < soil moisture
OBJECTIVE: What creates variation in
climate and how does it explain the
diversity and distribution of biomes?
•
•
•
•
Build a model for proximal causes
of global variation in climate and
biomes
What features of the earth
contribute to climatic variation?
What are causes of temporal
changes in climate and biomes?
What are local effects on climate?