Global%20Warming

1
Global Warming

• Is Human-Induced Climate Change Going To Destroy
  The World?
• Ok thats a bit dramatic. But, good questions
  are
• What is the evidence for recent climate change?
• Do we need to worry about it what are the
  consequences?
• What can we do about it?

Data and diagrams from Richard Deem, Michael
Mann, Lee Kump and the Intergovermental Panel on
Climate Change
2
History of Earths Atmosphere/Climate

• Earth formed 4.6 billion years ago
• Originally very hot, probably molten, early
  impact forming the moon
• Any early atmosphere removed by initiation of
  suns fusion reactions and solar wind
• Granitic crust and liquid water was present by
  4.3 billion years ago (zircon dating)
• However, much of Earths early history was erased
  during late heavy bombardment (3.9 billion years
  ago)

3
History of Earths Atmosphere/Climate

• First life appeared by 3.8 Ga
• Photosynthesis began 3.5-2.5 Ga, clear evidence
  for significant oxygen in the atmosphere by 2.0
  Ga
• Photosynthesis introduced oxygen and removed
  carbon dioxide and methane (greenhouse gases)
• Earth began current cycles of glacial and
  interglacial periods 3 Ma

4
Earths Temperature
5
Earths Temperature
6
Earths Temperature
7
Earths Temperature
8
Greenhouse Effect
Sun
9
Earths Atmospheric Gases
99
Non-Greenhouse Gases
1
Greenhouse Gases
10
Runaway Greenhouse Effect
Sun

• 97 CO2
• 3 N2
• Water sulfuric acid clouds
• Temperature860F (hotter than Mercury which is
  nearest to the sun)

11
Carbon Dioxide Levels
420
370
320
CO2 (ppm)
270
220
Vostok Ice Core
Dome Concordia
170
200000
400000
600000
0
Time (YBP)
12
Worldwide Carbon Emissions
8
7
6
5
Carbon (109 metric tons)
4
3
2
1
0
1750
1800
1850
1900
1950
2000
Year
13
Annual Carbon Emissions
8
6
Carbon (109 metric tons)
4
2
0
1955
1965
1975
1985
1995
2005
Year
14
Future Atmospheric CO2 Levels?

• Increasing CO2 emissions, especially in China and
  developing countries
• Likely to double within 150 years
• Increased coal usage
• Increased natural gas usage
• Decreased petroleum usage (increased cost and
  decreasing supply)

15
Kyoto Protocol

• Adopted in 1997
• Cut CO2 emissions by 5 from 1990 levels for
  2008-2012
• Really is symbolic only, since such levels of
  reduction will likely not significantly impact
  global warming

16
Recorded Worldwide Temperatures
0.8
0.6
0.4
0.2
D Mean Temperature (C)
0.0
-0.2
-0.4
-0.6
1880
1900
1920
1940
1960
1980
2000
Year
17
2007 Temperature Changes Compared to 1951-1980
18
Past Temperatures Measurement

• Proxy a method that approximates a particular
  measurement (e.g., temperature)
• Ice cores
• Pollen records
• Plant macrofossils
• Sr/Ca isotope data
• Oxygen isotopes from speleothem calcite
  (stalactites and stalagmites)

19
Temperature History of the Earth

• Little ice age (1400-1840) 1C cooler
• Medieval warm period (800-1300) 1C warmer than
  today
• Cool/warm cycles occur over 1,500 years
• Mostly due to changes in thermohaline circulation
  system of the ocean

20
Temperature History of the Earth

• For the past 3 Ma, the Earth has been
  experiencing 100 ka cycles of glaciation
  followed by 10 ka interglacial periods
• These climate periods are largely the result of
  cycles in the earths orbit precession,
  obliquity, and eccentricity

21
Orbital Parameters Earths Climate
1000
900
800
700
600
500
400
300
200
100
0
Age (ka)
22
Temperature History of the Earth

• For the past 3 Ma the earth has been experiencing
  100 ka cycles of glaciation followed by 10 ka
  interglacial periods
• Last ice age began ending 15,000 years ago, but
  was interrupted by the Younger Dryas event
  12,900 years ago

23
Hockey Stick Controversey
0.6
Direct temperature measurements Mann et al. 1999
0.4
0.2
0
Temperature Change (C)
-0.2
-0.4
-0.6
-0.8
1000
1200
1400
1600
1800
2000
Year
24
CO2 Concentration Vs. Temperature
370
320
31
30
SST (C) Tropical Pacific
CO2 (ppm) Antarctica
270
29
28
220
27
26
170
25
0
200000
400000
600000
Time (YBP)
25
Consequences of Global Warming Primarily Impacts
the Northern Hemisphere and Land Masses
Northern vs. Southern Latitude
Land vs. Ocean
1.0
Land Ocean
Northern Hemisphere Southern Hemisphere
0.8
0.6
0.4
0.2
Temperature Change (C)
0.0
-0.2
-0.4
-0.6
1920
1960
2000
1920
1960
2000
Year
Year
26
2007 Temperature Changes Compared to 1951-1980
27
Consqeuences of Global Warming Ice Sheets
Melting?

• GRACE (gravity measured by satellite) found
  melting in Antarctica equivalent to sea level
  rise of 0.4 mm/year (2 in/century)
• Zwally, 2005 (satellite radar altimetry)
• confirmed Antarctica melting
• Greenland ice melting onexterior, accumulating
  inland(higher precipitation)
• And - Glaciers are retreating
• all over the world.

28
Consqeuences of Global Warming Rise in Sea
Levels?

• Present rate is 1.8 0.3 mm/yr (7.4 in/century)
• Accelerating at a rate of 0.013 0.006 mm/yr2
• If acceleration continues, could result in 12
  in/century sea level rise
• Scenarios claiming 1 meter or more rise are
  probably unrealistic

29
Consqeuences of Global Warming How Much
Temperature Increase?

• Some models propose up to 9C increase this
  century
• Two studies put the minimum at 1.5C and maximum
  at 4.5C or 6.2C
• Another study puts the minimum at 2.5C
• Summary most studies suggest 4C over the next
  century

30
Potential Worldwide Precipitation Changes
31
Mitigation of Global Warming?

• Conservation
• Reduce energy needs
• Recycling
• Alternate energy sources
• Nuclear
• Wind
• Geothermal
• Hydroelectric
• Solar
• Fusion?

32
Conclusions

• Global warming is happening
• Most warming is probably the result of human
  activities but this is still under debate
• There will be positive and negative (mostly)
  repercussions from global warming
• The costs to mitigate global warming will be high
  are they worthwhile?

33

• Extra slides 2010 beyond this point

34
Historic Los Angeles Temperatures
35
Main Ocean Currents
Adapted from IPCC SYR Figure 4-2
36
Younger Dryas Event Greenland Data
-25
0.35
-30
0.30
-35
0.25
Snow Accumulation (m/yr)
-40
0.20
Temperature (C)
-45
0.15
-50
0.10
-55
0.05
0
5
10
15
20
Age (ka)
37
Is the Hockey Stick Correct?
2
Mann et al. 1999 Esper et al. 2002
1
0
Temperature Change (C)
-1
-2
800
1000
1200
1400
1600
1800
2000
Year
38
Is the Hockey Stick Correct?
0.4
0.2
0.0
-0.2
-0.4
Temperature Change (C)
-0.6
-0.8
-1.0
-1.2
0
400
800
1200
1600
2000
Year
39
U.S. National Academy of Sciences June 2006
0.6
0.4
0.2
0
Temperature Change (C)
-0.2
-0.4
-0.6
-0.8
1000
1200
1400
1600
1800
2000
Year
40
Changing Sea Levels
20
10
0
Relative Sea Level (cm)
-10
Amsterdam, Netherlands Brest, France Swinoujscie,
Poland
-20
1700
1750
1800
1850
1900
1950
2000
Adapted from IPCC SYR Figure 2-5
41
Sea Levels for 450,000 Years
31
20
0
30
-20
29
-40
Sea Level (m)
28
SST (C) Tropical Pacific
-60
27
-80
26
-100
-120
25
450
400
350
300
250
200
150
100
50
0
Time (Ka)