Review of chapter 1

1
Review of chapter 1

• What is an ecosystem?
• How big is it?
• Difference between state factor, slow variable
  and fast variable?
• So what?
• How do feedbacks influence stability?
• What are ecosystem services?
• Why should we care?

2
Chap. 2 The Climate System

• Climate is single best predictor of ecosystem
  structure and functioning
• Geographic distribution of climate is relatively
  predictable from general principles
• Temporal variation in climate depends on solar
  input, surface properties, and the capacity of
  the atmosphere to trap heat
• Therefore, if you understand causes of spatial
  and temporal variation in climate, you can
  predict many of the ecosystem patterns that are
  observed.

3
Where is NPP highest? Lowest? What are the
latitudinal patterns? Other patterns?
4
How do precipitation patterns compare with those
of NPP?
5
How do temperature patterns compare with those of
NPP? Is temperature or precipitation a better fit
to NPP?
6
Climate depends on solar input, surface
properties, and trapping of heat by the
atmosphere. What is the major energy source that
drives the climate system? How does suns energy
differ from that of the Earth? Which type of
energy is absorbed most effectively by the
atmosphere?
7
Average energy budget of the earth- atmosphere
system in out 100 31 69
units 23 26 95 114 7 23 units
8
Stratosphere (UV protector) absorbs UV
heated from the top Troposphere (the weather
layer) absorbs longwave radiation heated
from the bottom
9
Atmospheric circulation driven by uneven heating
of Earth Suns rays most perpendicular at
equator Shorter atmospheric path near
equator Therefore more energy absorbed per unit
area at equator Energy in must equal energy out
for the Earth System This drives heat
movement from equator toward poles
10
Vertical mixing drives circulation cells
Rising air at equator Sinking air at poles
Transfers heat from equator to poles
11
Coriolis forces(circular motion of atmosphere)

• Earth rotates from west to east
• So does atmosphere, but also moves north and
  south
• Atmosphere maintains momentum
• Relative to Earth surface
• Poleward air increases its speed
• Westerly wind (winds move west to east)
• Equatorward air reduces its speed
• Easterly winds (winds move east to west)

12
Vertical mixing drives circulation cells
Coriolis forces drive wind directions
13
Presence of continents and oceans influences
1. Rising and sinking of air (high and low
pressure centers) 2. Wind patterns (storm
tracks)
14
Ocean circulation accounts for 40 of poleward
heat transport driven by Coriolis forces and
surface winds has strong effects on regional
climate patterns
15
Thermohaline circulation important in poleward
heat transport driven by deep water formation
at poles drives upwelling at eastern margins
of ocean basins
16
Questions

• Why are the tropics warmer than the arctic?
• How does heat move latitudinally?
• How do coastal and interior climate differ? (and
  why?)
• Why do west coasts differ from east coasts of
  continents?

17
Landform effects on climate

• Winds due to heating contrasts
• Hadley cell (long-term climate patterns)
• Monsoons (seasonal patterns)
• Land-sea breezes (diurnal patterns)
• Topographic effects
• Planetary waves
• Rain shadow
• Lapse rate (vertical temperature gradient)
• North vs. south slope heating contrast
• Local effects (inversions, katabatic winds)

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Pick a spot on this map (e.g., where you were
born) Explain why it has the climate it does.
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Foley et al. 2003
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Potential climatic consequences of tropical
deforestation (computer simulation model)
warmer drier climate
27
Fire alters energy exchange Negative feedback to
climate warming
Baldochi
28
Clearing for agriculture in W. Australia altered
climate 30 less ppt over farmlands 10 more
ppt over heathlands Why?
Photo S. Chambers
29
Land clearing changes energy balance Higher
albedo (less energy absorbed) More ET from
irrigation (cools surface) Less sensible heat
(less convective uplift
30
Vegetation effects on climate

• Vegetation alters surface properties
• How????
• So what???

31
Temporal variations in climate

• Mainly driven by changes in solar input
• Evolution of sun (evolution of climate system)
• Variations in Earths orbit (ice ages)
• Seasonal cycles
• Diurnal cycles
• Changes in surface heat absorption and heat
  trapping of atmosphere are now becoming important
  (human impacts)

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Evolution of the sun
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Changes in Earths orbit
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Ice ages
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The last 1000 years
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Human causes of climate warming
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Seasonal variation in solar input
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Relationship of ecosystem type to climate
42
Seasonality of temperature and precipitation
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Global to arctic
Mann et al.
Polar amplification
Chapman and Chapin
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Glaciers are melting
European arctic
Russian arctic
Total arctic
American arctic
Hinzman
47
The season for tundra travel is shorter (later
snowfall, earlier snowmelt)
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Sea ice is becoming less extensive
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Permafrost is warmer
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1949
1949
Shrub density has increased
2000
Sturm
Chandler River, 50 miles S. of Umiat Sturm,
Racine and Tape Fifty Years of Change in Arctic
Alaskan Shrub Abundance
52
Forests are expanding
Lloyd and Fastie
53
Planetary boundary layer layer that interacts
with surface shallow at night when less
convective mixing by wind concentrates
products of ecosystem (CO2, pollutants)
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