Download Climate Change

Climate Change
Chapter 18
Global Change
 Population growth
 Distribution of water
 Distribution of food
 Climate change
Climate Change
 Earth’s average surface temperature
 Distribution of rainfall
 Patterns of temperature change and
global conveyor belt
Factors Affecting Global
Climate Change
 Relationship of Earth to Sun
 Anthropogenic causes
Anthropogenic Causes
 Atmospheric change due to carbon
dioxide emissions, methane emissions,
destruction of ozone by providing more
surfaces-free radicals for reactions to
occur in stratosphere (SOX, NOX, CO2,
CH4), changes in vegetative cover,
water pollution - eutrophication
Average surface temperature (°C)
17
16
15
14
13
12
11
10
9
900
800
700
600
500
400
300
Thousands of years ago
200
100
Average temperature over past 900,000
years
Present
Fig. 18.2a, p. 447
2
Temperature change (°C)
Agriculture established
1
0
-1
-2
End of
last ice
age
-3
Average temperature over past
10,000 years = 15°C (59°F)
-4
-5
20,000
10,000
2,000
1,000
Years ago
200
Temperature change over past
22,000 years
100
Now
Fig. 18.2b, p. 447
Temperature change (°C)
1.0
0.5
0.0
-0.5
-1.0
1000 1100 1200 1300 1400 1500 1600 1700
Year
1800 1900 2000 2101
Temperature change over past 1,000
years
Fig. 18.2c, p. 447
Average surface temperature (°C)
15.0
14.8
14.6
14.4
14.2
14.0
13.8
13.6
1860
1880
1900
1920
1940
Year
1960
1980
Average temperature over past 130
years
2000
2020
Fig. 18.2d, p. 447
How do we know?
 Recent history-have sufficient data from a
variety of sources (hot air balloons, buoys,
satellite data, pollen records, coral...)
 Ancient history- ice cores (Vostock), rocks,
tree rings )
 Geologic history-, deep ocean
sampling(plankton & radioisotopes),
rocks(fossils & radioisotopes)
Evidence of Global Change
How is this information
processed?
 Modeling
 # factors, depth of data, period of time
Global cooling and warming
cycles
 Global cooling, Ice Ages, last about
100,000 years
 Global warming, interglacial periods,
last about 10,000 to 13,000 years
 Currently, we are living in an interglacial
period
Climate and global warming
 Climate is statistics of meteorological
conditions, temperature, precipitation,
winds, over a long period of time-at
least 30 years
 0.5C of warming has occurred in last
130 years with the 1980s the warmest
during that period
 Pattern parallels that of fossil fuel use
and injection into the atmosphere of
gases that can absorb radiation and
lead to global warming
Greenhouse Effect
 Molecules of atmospheric gases vibrate
and transform the absorbed energy into
longer wavelength infrared radiation in
the troposphere
 Convection currents distribute the heat
l of greenhouse gases
 Atmosphere is good absorber
of infrared radiation (7.5 mm)
 CO2 and H2O vapor limit
transmission to space at
many l
Variation of
Temperature,
pressure, and
altitude above
Earth’s surface
Global Energy Balance for Atmosphere
Numbers are %energy from incoming solar radiation
Greenhouse Effect
 Half of solar heat goes into latent heat,
absorbed by water changing to water
vapor
 Of 47% of initial solar energy absorbed
at Earth’s surface, only 18% lost by
radiation
 The remainder is captured by
atmosphere-surface cycling which
causes Earth to be 33C warmer than is
would be without an atmosphere
Tropospheric heating effect
 Arrhenius !!!!! 1896
 Not a guess, data supports
 Is THEORY in atmospheric science
Average Surface Temperature
is about 15C (60F)
 Due to combination of greenhouse and
global cooling processes
 Cooling processes: heat absorbed by
evaporation of water, and water vapor
stores heat in upper atmosphere
(thermosphere)
Greenhouse Gas
 CO2 fossil fuel burning (75%), biomass






burning
CH4 rice, cows, landfills, coal production, coal
seams, natural gas leaks, oil production
N2O fossil fuel burning, fertilizers, livestock
wastes, nylon prod
CFCs air conditioners, refrigerators, foams
HCFCs-” “
Halons- fire extinguishers
CCl4 cleaning solvent
360
340
320
300
280
Carbon dioxide
260
240
220
+2.5
200
0
180
–2.5
–5.0
Temperature
change
End of
last ice age
160
120
80
40
0
Thousands of years before present
–7.5
–10.0
Variation of temperature (˚C)
from current level
Concentration of carbon dioxide
in the atmosphere (ppm)
Correlation
between CO2
and Temp
Change
380
Fig. 18.3, p. 449
Surface Ozone:
Top is
Preindustrial and
Lower frame is
current (2002)
Changes in
atmosphere,
geosphere, &
biosphere from
glacial to
interglacial
periods
Ozone over Antarctica 1979 to 1990
Measurement of Air pollution from satellite
Drought from June to August in global
climate model
Global Ocean Temp at depth of 160 m
(vol transport stream)
Carbon dioxide
Methane
Nitrous oxide
Index (1900 = 100)
250
Projected
emissions
200
150
100
1990
2000
2025
2050
Year
2075
2100
Fig. 18.5, p. 451
Global warming is cyclical; the
rate is not
 The rate of global warming is greater than past







interglacial periods
The CO2 in troposphere is higher than probably the
last 20 million years
75% of CO2 since 1980 is due to fossil fuel burning;
remainder is human changes in land use
Average global temp has >0.6C mostly since 1946
Since 1861 9 of 10 warmest years have occurred
since 1990 with the hottest in 1998 and 2001
Ice caps and glaciers shrinking
Global sea level rise of 10-20 cm in 100 years
Plants and animals are migrating north to meet
optimum temperatures
Global Change
 Affect the availability of water resources
by altering rates of evaporation and
precipitation
 Shift areas where crops can be grown
 Change average sea levels
 Alter the structure and location of the
world’s biomes
Positive feedback
 More product results in more production-eg. “nothing




succeeds like success”
Greater temp, more melting of snow, loss of albedo
effect results in greater temp and still more melting of
snow
Thawing soil results in more microbial activity; more
microbial activity results in more CO2 and more
thawing soil
Arctic circle, Greenland, and Antarctica all have
thinning ice sheets, particularly Greenland
The influx of freshwater from melting glaciers on
Greenland could stop the global conveyor belt in the
Atlantic
Global conveyor belt
Greenland
Cold water melting from
Antarctica's ice cap and
icebergs falls to the ocean floor
and surges northward, affecting
worldwide circulation.
Antarctica
Fig. 18.10, p. 456
Temperature change (°C) from 1980–99 mean
1.2
Observed
1.0
0.8
Model of greenhouse
gases + aerosols +
solar output
0.6
0.4
0.2
0.0
-0.2
1860 1880
1900
1920
1940
Year
1960
1980
2000 2010
Fig. 18.7, p. 453
Climate Models and IPCC
 IPCC: Intergovernmental Panel on Climate




Change 2,000 climate scientists
90-95% chance that earth’s mean surface temp
will >1.4-5.8C between 2000 and 2100; change
btwn 2000 and 2030 will equal that of entire
20th century
Many greenhouse gases show increases due to
anthropogenic activities
Bush administration 2002 says climate changes
anthropogenic and then reject Kyoto Treaty!
Climate models are only models & have
limitations
Building models
 Transect atmosphere mathematically
 Assign initial boundary condition for each
variable to each cell in layer (solar radiation,
precipitation, heat radiated by earth,
cloudiness, interactions btwn atmosphere and
oceans, greenhouse gases, & air pollutants)
 Develop equations that connect cells so vary
together
 Run model to simulate changes that can be
verified and then run to project future
changes
 Reliability tied to accuracy of data inputs and
magnification of errors over time, & chaos
6.0
5.5
5.0
Change in temperature (ºC)
4.5
4.0
3.5
3.0
Measured vs
predicted
temperature
changes
2.5
2.0
1.5
1.0
0.5
0
1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 2100
Year
Fig. 18.8, p. 453
Change will not be evenly
distributed
 Temp increases higher over land than
over oceans
 Greater in high latitudes near earth’s
poles than in lower latitude equatorial
regions
 Much higher in inland regions in the
northern latitudes
Agriculture
•
Shifts in food-growing
areas
•
Changes in crop yields
•
Increased irrigation
demands
•
Increased pests, crop
diseases, and weeds in
warmer areas
Water Resources
• Changes in water supply
• Decreased water quality
• Increased drought
• Increased flooding
Forests
•
Changes in forest
composition and locations
•
Disappearance of some
forests
•
Increased fires from drying
•
Loss of wildlife habitat and
species
Biodiversity
Sea Level and Coastal Areas
•
Extinction of some plant
and animal species
•
•
•
Loss of habitats
•
•
Disruption of aquatic life
•
•
•
Weather Extremes
•
Prolonged heat waves
and droughts
•
Increased flooding
•
More intense
hurricanes, typhoons,
tornadoes, and
violent storms
Rising sea levels
Flooding of low-lying islands
and coastal cities
Flooding of coastal estuaries,
wetlands, and coral reefs
Beach erosion
Disruption of coastal
fisheries
Contamination of coastal
aquifiers with salt water
Human Health
Human Population
• Increased deaths
• More environmental
refugees
• Increased migration
•
Increased deaths from heat
and disease
•
Disruption of food and water
supplies
•
Spread of tropical diseases to
temperate areas
•
Increased respiratory disease
•
Increased water pollution
from coastal flooding
Fig. 18.12, p. 458
Ultraviolet light hits a chlorofluorocarbon
(CFC) molecule, such as CFCl3, breaking
off a chlorine atom and leaving
CFCl2.
Sun
Cl
Cl
C
F
Cl
UV radiation
Once free, the chlorine atom is off
to attack another ozone molecule
and begin the cycle again.
Cl
Cl
O
O
The chlorine atom attacks
an ozone (O3) molecule,
pulling an oxygen atom
off it and leaving
O
O
O
an oxygen
molecule (O2).
Cl
Summary of Reactions
CCl3F + UV Cl + CCl2F
Cl + O3 ClO + O2
Repeated
Cl + O Cl + O2
many times
A free oxygen atom pulls
the oxygen atom off
the chlorine monoxide
Cl
molecule to form O2.
O
O
Cl
The chlorine
atom and the
O
oxygen atom join
O
to form a chlorine
monoxide molecule O
(ClO).
Fig. 18.16, p. 466