Transcript Global Warming - UNLV Geoscience

Global Warming
Is Human-Induced Climate Change
Going To Destroy The World?
Ok… that’s a bit dramatic. But, good
questions are:
1) What is the evidence for recent climate change?
2) Do we need to worry about it – what are the consequences?
3) What can we do about it?
Data and diagrams from Richard Deem, Michael Mann, Lee Kump
and the Intergovermental Panel on Climate Change
History of Earth’s
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 sun’s fusion reactions and solar wind
• Granitic crust and liquid water was present
by ~4.3 billion years ago (zircon dating)
• However, much of Earth’s early history was
erased during late heavy bombardment (~3.9
billion years ago)
History of Earth’s
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
Solar Energy
Sun
Solar Energy
Earth’s Temperature
Earth’s Temperature
Sun
Solar
Energy
Radiative
Cooling
Earth’s Temperature
Sun
Solar
Energy
Radiative
Cooling
Earth’s Temperature
Sun
Solar
Energy
Radiative
Cooling
Sun
Greenhouse Effect
Earth’s Atmospheric Gases
Nitrogen (N2)
Oxygen (O2)
Water (H2O)
Carbon Dioxide (CO2)
Methane (CH4)
99%
NonGreenhouse
Gases
1%
Greenhouse
Gases
Sun
Runaway Greenhouse Effect
• 97% CO2
• 3% N2
• Water & sulfuric
acid clouds
• Temperature:
860°F (hotter than
Mercury which is
nearest to the sun)
Venus
CO2 (ppm)
420
Carbon Dioxide Levels
CO2 (ppm)
370
320
Muana Loa Readings
CO2 Levels Since 1958
370
350
330
310
40 30 20 10 0
270
220
Dome Concordia
170 600000
Vostok Ice Core
400000
200000
Time (YBP)
0
Carbon (109 metric tons)
Worldwide Carbon Emissions
8
7
6
5
Total
Liquid fuel
Solid fuel
Gas fuel
4
3
2
1
0
1750
1800
1850
1900
Year
1950
2000
Carbon (109 metric tons)
8
Annual Carbon Emissions
6
Annual carbon emissions
Atmospheric CO2
Atmospheric CO2 average
4
2
0
1955
1965
1975
1985
Year
1995
2005
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)
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
D Mean Temperature (°C)
0.8
Recorded Worldwide
Temperatures
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
1880
1900
1920
1940
Year
1960
1980
2000
2007 Temperature Changes
Compared to 1951-1980
-3
-2.5 -1.5
-1
-.5
-.1
.1
.5
1
1.5
2.5
3.4
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)
Temperature History of the Earth
• Little ice age (1400-1840) – 1°C cooler
• Medieval warm period (800-1300) – 1°C
warmer than today
• Cool/warm cycles occur over ~1,500 years
• Mostly due to changes in thermohaline
circulation system of the ocean
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 earth’s orbit –
precession, obliquity, and eccentricity
Orbital Parameters & Earth’s Climate
Precession
(22 ka)
Obliquity
(41 ka)
Eccentricity
(100 ka)
Temperature
1000 900 800 700 600 500 400 300 200 100 0
Age (ka)
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
Temperature Change (°C)
“Hockey Stick” Controversey
0.6
0.4
Direct temperature measurements
Mann et al. 1999
0.2
0
-0.2
-0.4
-0.6
-0.8
1000
1200
1400
1600
Year
1800
2000
CO2 (ppm) Antarctica
370
320
270
220
170
600000
400000 200000
Time (YBP)
31
30
29
28
27
26
025
SST (°C) Tropical Pacific
CO2 Concentration Vs. Temperature
Consequences of Global Warming:
Primarily Impacts the Northern
Hemisphere and Land Masses
Temperature Change (°C)
Northern vs. Southern Latitude
Land vs. Ocean
1.0
0.8
0.6
Northern Hemisphere
Southern Hemisphere
Land
Ocean
0.4
0.2
0.0
-0.2
-0.4
-0.6
1920
1960
Year
2000
1920
1960
Year
2000
2007 Temperature Changes
Compared to 1951-1980
-3
-2.5 -1.5
-1
-.5
-.1
.1
.5
1
1.5
2.5
3.4
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 on
exterior, accumulating inland
(higher precipitation)
• And - Glaciers are retreating
all over the world.
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
Consqeuences of Global Warming:
How Much Temperature Increase?
• Some models propose up to 9°C
increase this century
• Two studies put the minimum at 1.5°C
and maximum at 4.5°C or 6.2°C
• Another study puts the minimum at
2.5°C
• Summary – most studies suggest ~4°C
over the next century
Potential Worldwide Precipitation
Changes
-50
-20
-10
-5
5
10
20
50
Mitigation of Global Warming?
• Conservation
• Reduce energy needs
• Recycling
• Alternate energy sources
•
•
•
•
•
•
Nuclear
Wind
Geothermal
Hydroelectric
Solar
Fusion?
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?
• Extra slides 2010 beyond this point
Historic Los Angeles
Temperatures
Temperature (°C)
Annual Temperatures
Summer Temperatures
Winter Temperatures
22
25
17
21
24
16
20
23
15
19
22
14
18
21
13
17
20
12
16
19
11
15
18
10
1880 1900 1920 1940 1960 1980 2000
1880 1900 1920 1940 1960 1980 2000
1880 1900 1920 1940 1960 1980 2000
Year
Year
Year
Main Ocean Currents
Adapted from IPCC SYR Figure 4-2
Temperature (°C)
-25
-30
0.35
Younger
Dryas
0.30
Medieval Warm
-35
-40 Ice Age
0.25
Little Ice Age 0.20
-45
0.15
-50
0.10
-55
20
15
10
Age (ka)
5
0.05
0
Snow Accumulation (m/yr)
Younger Dryas Event – Greenland Data
Temperature Change (°C)
Is the Hockey Stick Correct?
2
Mann et al. 1999
Esper et al. 2002
1
0
-1
-2
800
1000
1200
1400
Year
1600
1800
2000
Is the Hockey Stick Correct?
Temperature Change (°C)
0.4
0.2
0.0
-0.2
-0.4
-0.6
Mann et al. 1999
Esper et al. 2002
Moberg et al. 2005
Mann et al. 2008
-0.8
-1.0
-1.2
0
400
800
1200
Year
1600
2000
Temperature Change (°C)
U.S. National Academy of
Sciences: June 2006
0.6
0.4
“2:1 chance of being right”
“high level of confidence”
0.2
0
-0.2
-0.4
-0.6
-0.8
1000
1200
1400
1600
Year
1800
2000
Changing Sea Levels
Relative Sea Level (cm)
Global Temperature Change
20
10
0
-10
-20
1700
Amsterdam, Netherlands
Brest, France
Swinoujscie, Poland
1750
1800
1850
1900
1950
2000
Adapted from IPCC SYR Figure 2-5
20
31
0
30
-20
29
-40
28
-60
-80
27
-100
26
-120
25
450 400 350 300 250 200 150 100 50
Time (Ka)
0
SST (°C) Tropical Pacific
Sea Level (m)
Sea Levels for 450,000 Years