Post on 29-Dec-2015
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
Thousands of years ago
Ave
rag
e su
rfac
e te
mp
erat
ure
(°C
)
900 800 700 600 500 400 300 200 100 Present9
10
11
12
13
14
15
16
17
Fig. 18.2a, p. 447
Average temperature over past 900,000 years
Years ago
Tem
per
atu
re c
han
ge
(°C
)
20,000 10,000 2,000 1,000 200 100 Now
-5
-4
-3
-2
-1
0
1
2
End oflast iceage
Agriculture established
Average temperature over past10,000 years = 15°C (59°F)
Fig. 18.2b, p. 447
Temperature change over past 22,000 years
Year
Tem
per
atu
re c
han
ge
(°C
)
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2101
-1.0
-0.5
0.0
0.5
1.0
Fig. 18.2c, p. 447
Temperature change over past 1,000 years
Year
Ave
rag
e su
rfac
e te
mp
erat
ure
(°C
)
1860 1880 1900 1920 1940 1960 1980 2000 2020
13.6
13.8
14.0
14.2
14.4
14.6
14.8
15.0
Fig. 18.2d, p. 447
Average temperature over past 130 years
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
of greenhouse gases Atmosphere is good absorber
of infrared radiation (7.5 m) CO2 and H2O vapor limit
transmission to space at many
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
Carbon dioxide
Temperaturechange End of
last ice age
160 120 80 40 0Thousands of years before present
Co
nc
entr
ati
on
of
carb
on
dio
xid
ein
th
e a
tmo
sph
ere
(p
pm
)
180
200
220
240
260
280
300
320
340
360
380
–10.0
–7.5
–5.0
–2.5
0
+2.5
Va
riat
ion
of
tem
pe
ratu
re (
˚C)
fro
m c
urr
en
t le
vel
Fig. 18.3, p. 449
Correlation between CO2 and Temp Change
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)
Year1990 2000 2025 2050 2075 2100
100
150
200
250
Ind
ex
(19
00
= 1
00
)Carbon dioxide
MethaneNitrous oxide
Fig. 18.5, p. 451
Projected emissions
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
Antarctica
Cold water melting fromAntarctica's ice cap and
icebergs falls to the ocean floor and surges northward, affecting
worldwide circulation.
Cold water melting fromAntarctica's ice cap and
icebergs falls to the ocean floor and surges northward, affecting
worldwide circulation.
GreenlandGreenland
Fig. 18.10, p. 456
Global conveyor belt
Year1860 1880 1900 1920 1940 1960 1980 2000 2010
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Observed
Model of greenhouse gases + aerosols + solar output
Tem
per
atu
re c
han
ge
(°C
) fr
om
198
0–99
mea
n
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
Year
1850 1875 1900 1925 1950 1975 2000 2025 2050 2075 21000
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Ch
ang
e in
tem
per
atu
re (
ºC)
Fig. 18.8, p. 453
Measured vs predicted temperature changes
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
• 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
Human Health
• 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
Sea Level and Coastal Areas
• Changes in forest composition and locations
• Disappearance of some forests
• Increased fires from drying
• Loss of wildlife habitat and species
Forests
• Changes in water supply
• Decreased water quality
• Increased drought
• Increased flooding
Water Resources
• Shifts in food-growing areas
• Changes in crop yields
• Increased irrigation demands
• Increased pests, crop diseases, and weeds in warmer areas
Agriculture
• Extinction of some plant and animal species
• Loss of habitats
• Disruption of aquatic life
Biodiversity
• Prolonged heat waves and droughts
• Increased flooding
• More intense hurricanes, typhoons, tornadoes, and violent storms
Weather Extremes
• Increased deaths
• More environmental refugees
• Increased migration
Human Population
Fig. 18.12, p. 458
Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breakingoff a chlorine atom and leaving CFCl2.
UV radiation
Sun
Once free, the chlorine atom is off to attack another ozone moleculeand begin the cycle again.
A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O2.
The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO).
The chlorine atom attacksan ozone (O3) molecule, pulling an oxygen atom off it and leaving an oxygen molecule (O2).
Cl
Cl
ClC
F
Cl
Cl
OO
Cl
OO
O
Cl
O
OO
ClO
O
Summary of ReactionsCCl3F + UV Cl + CCl2FCl + O3 ClO + O2
Cl + O Cl + O2
Repeated many times
Fig. 18.16, p. 466