MET 112 Global Climate Change

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MET 112 Global Climate Change

• Final Review
• Dr. Eugene Cordero

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• Lecture 2-3

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Solar vs. Terrestrial Radiation

• The sun is much hotter than planets therefore,
  sunlight consists of shorter wavelengths than
  planetary radiation
• Thus

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Some atmospheric radiation escapes to space
Some surface radiation escapes to space
Greenhouse gases emit longwave upward and downward
Most outgoing longwave is absorbed in atmosphere
(by greenhouse gases)
Some atmospheric radiation is absorbed at the
surface
Longwave radiation is emitted from surface.
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• Lecture 4

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Why do we have seasons?
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Controls on Climate

• Seasonal temperature and precipitation patters
  are generally attributable to
• Latitude
• Mountains and highlands
• Land and water location
• Prevailing winds
• Pressure and wind systems
• Ocean currents

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• Lecture 5

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Water freely evaporating and condensing
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• Lecture 6-7

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Temperature Graph
Source http//www.ruf.rice.edu/leeman/aNR.html
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Figure 1 Variations of the Earths surface
temperature over the last 140 years and the last
millennium.(a) The Earths surface temperature
is shown year by year (red bars) and
approximately decade by decade (black line, a
filtered annual curve suppressing fluctuations
below near decadal time-scales). There are
uncertainties in the annual data (thin black
whisker bars represent the 95 confidence range)
due to data gaps, random instrumental errors and
uncertainties, uncertainties in bias corrections
in the ocean surface temperature data and also in
adjustments for urbanisation over the land. Over
both the last 140 years and 100 years, the best
estimate is that the global average surface
temperature has increased by 0.6 0.2C.
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• Lecture 8

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The Faint-Sun Paradox (Cont.)

• What would happen if the suns energy output
  dropped by 30?
• With todays albedo and greenhouse gas
  concentrations, here is what would happen to the
  surface temperature as the sun got weaker and
  weaker

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• Lecture 9-10

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The Earths history can be characterized by
different geologic events or eras.
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Silicate-to-Carbonate Conversion
Rain
1. CO2 Dissolves in Rainwater
2. Acid Dissolves Silicates (carbonic acid)
3. Dissolved Material Transported to Oceans
4. CaCO3 Forms in Ocean and Settles to the Bottom
Land
Calcium carbonate
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The (Almost) Complete Long-Term Carbon Cycle
(Diagram)
Atmosphere (CO2) Ocean (Dissolved CO2) Biosphere
(Organic Carbon)
Subduction/Volcanism
Oxidation of Buried Organic Carbon
Silicate-to-Carbonate Conversion
Organic Carbon Burial
Carbonates
Buried Organic Carbon
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• Lecture 11

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Time period
Cambrian Explosion
Freeze-Fry Episodes
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Ice-Albedo Feedback (Cooling)
Initiating Mechanism
Earth Cools
Somehow this happens
Ice Coverage Increases
Positive Feedback
Albedo Increases
Absorption of Sunlight Decreases
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Possible Role of Cloud in Warming or Cooling the
Atmosphere
Positive Feedback
Negative Feedback
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• Lecture 12

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Results from Daisyworld
Optimum temps for daisies
T2
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• Lecture 13

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External Forcing

• Variations in solar output
• Orbital variations
• Meteors

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Orbital changes

• Milankovitch theory
• Serbian astrophysicist in 1920s who studied
  effects of solar radiation on the irregularity of
  ice ages
• Variations in the Earths orbit
• Changes in shape of the earths orbit around sun
  
• Eccentricity (100,000 years)
• Wobbling of the earths axis of rotation
• Precession (22,000 years)
• Changes in the tilt of earths axis
• Obliquity (41,000 years)

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Internal Forcing

• ____________________________
• ____________________________
• Ocean changes
• Chemical changes in the atmosphere (i.e. CO2)
• Natural
• Anthropogenic (human produced)

Plate tectonics/mountain building
Volcanoes
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The Enhanced Greenhouse Effect

• Burning of fossil fuels and changes in land cause
  an increase in greenhouse gas concentrations.
• Enhanced greenhouse gases are expected to lead to
  a warmer climate.
• __________ and ___________are two important
  anthropogenic greenhouse gases.

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Current CO2 370 ppm
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Greenhouse warming effectiveness

• Different gases vary in their ability to act as a
  greenhouse warmer.
• Gas Concentration (ppm) Greenhouse
• warming(W/m-2)
• Water Vapor 3000 100
• Carbon Dioxide 353 50
• Methane 1.72 1.7
• Nitrous oxide 0.31 1.3
• Ozone 0.01-0.1 1.3
• CFC11 0.00028 0.06
• CFC12 0.00484 0.12

Strength of warming
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• Lecture 14

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Atmospheric Aerosols

• Microscopic liquid/solid particles
• Natural sources
• Volcanoes (sulfur)
• Fires, dust
• Dust, sulfate particles reflect incoming
  sunlight ___________________
• Smoky soot absorb incoming sunlight
• ____________________

Cool atmosphere
warm atmosphere
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• Lecture 15

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Radiative Forcing from the IPCC
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• Lecture 16

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• Lecture 17

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Burning of Fossil Fuels

• Fossil Fuels Fuels obtained from the earth are
  part of the buried organic carbon reservoir
• Examples Coal, petroleum products, natural gas
• The burning of fossil fuels is essentially
• A large acceleration of the oxidation of buried
  organic carbon

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Land-Use Changes

• Deforestation
• The intentional clearing of forests for farmland
  and habitation
• This process is essentially an acceleration of
  one part of the short-term carbon cycle
• the decay of dead vegetation

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Carbon Budget Changes

• Units in Peta-grams (x1015) of Carbon per year
  (PgC/yr)
• Atmosphere increase 3.3 0.1
• Observations
• Emissions (fossil fuel, cement) 5.4 0.3
• Estimates from industry
• Ocean-atmosphere flux -1.9 0.6
• Estimates from models/obs
• Final component is Land/atmosphere flux

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Carbon Budget (II)

• Land atmosphere flux -0.20.7
• Must be to balance budget
• Land atmosphere flux partitioned as follows 
• Land use change 1.7
• From observations
• Residual terrestrial sink -1.9
• Calculated to balance land/atmosphere flux

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Human Perturbation of the Carbon Cycle
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• Lecture 18

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Scenarios
Emission Scenarios
SRES (special report on emission scenarios)
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Future Predictions Temperature
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Most of the observed warming in the past 50 years
is attributable to human activities
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Sea Level
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• Lecture 19

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Indicators of Climate Change
Fingerprints of climate change
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Sea-level transgression scenarios for Bangladesh
Adapted from Milliman et al. (1989).
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• Lecture 20

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Ozone, the good and the bad
Ozone is often confused Good ozone
Stratospheric ozone The ozone layer Bad
ozone Tropospheric ozone Smog
Stratosphere
Altitude (km)
Troposphere
ozone amount
Q1 At what altitude is the ozone layer a
maximum? Q2 Where is the ozone layer?
23-25 km Stratosphere
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Ozone profile with height and UV
Less harmful
More harmful
Ozone layer
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Location (latitude)
UV radiation

• What affects the amount of UV radiation hitting
  the Earth?
• _______________________
• _______________________
• _______________________
• _______________________
• _______________________

Time of year
Time of day
Cloud amount
Ozone amount

• The amount of UV radiation reaching the ground
  thus varies significantly

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• Lecture 21

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Ozone observations over Antarctica
What year did the ozone hole first appear?
early 1980s
Ozone hole definition
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Ozone Hole Recipe
Ozone Hole Formation
Only during winter
Cold Temperatures T-80C
Only during spring
produces
Ozone destroying chemicals
Sunlight
Polar Stratospheric Clouds
and
produces
produces
and
Chlorine gas
Ozone Hole
Everywhere in Atmosphere
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High Latitudes temperatures at 20km
N. Hem temperatures
Temperature required for ozone hole
S. Hem temperatures
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Ozone levels have changed over the last two
decades Largest declines in the high latitude
southern hemisphere
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• Lecture 22

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The Kyoto Protocol

• A United Nations sponsored effort
• Calls for reductions of greenhouse gas emissions
  by industrialized countries of 5.2 per cent below
  1990 levels.
• The Protocol will go into force after
• The protocol has been ratified by a minimum of 55
  countries.
• The ratifying nations comprise 55 of global
  greenhouse gas emissions.
• Current status
• 119 countries have signed accounting for 45 of
  global CO2.
• US not planning on signing protocol (US accounts
  for 25 of CO2 emitted)

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• What implication might future climate have on
  local industries?
• What are the uncertainties related to future
  climate change?