Transcript No Slide Title

INTRODUCTION TO
CLIMATE CHANGE
Robert K. Kaufmann
Museum of Science
July 11, 2005
http://www.bu.edu/cees/people/faculty/kaufmann/index.html
Global Climate Change
History of climate change
The energy balance of planet Earth
Human activity and radiatively active gases
Climate models:where and how much will climate change
Are humans responsible for climate change
Climate change impacts on the environment and economy
What if anything should be done about climate change?
Climate vs. Weather
Weather: Conditions on any given day
The temperature in Boston today is 86oF
Climate: Average conditions on any given day over
The average temperature in Boston on this
day is 82oF
15,000 Years of Temperature
1000 Years of Temperature
Observational Record
0.6
Degrees Celsius
0.4
0.2
0
-0.2
-0.4
-0.6
1860
1880
1900
1920
1940
1960
1980
2000
Heat Balance of Planet Earth
5800oK
lm = L/T
H2O
CO2
255oK
Ground
Ground
CH4
Radiatively Active Gases
Gas
Radiative
Forcing
CO2
1
Methane
11
Nitrous oxide 270
CFC-11
3,400
CFC-12
7,100
Atmospheric
Lifetime
120 years
10.5 years
13.2 years
55 years
116 years
Conc.
PPM
PPB
PPT
PPT
PPT
Radiative Forcing
1.5
1
0.5
0
-0.5
-1
-1.5
Carbon Dioxide
Methane
Solar Activity
Trace Gases
Anthropgenic Sulfates
Changes in
Out-Going
Radiation
1970-1997
How Do Humans Affect Radiative
Forcing?
7000
6000
5000
4000
3000
2000
1000
0
Fossil Fuel Combustion -- CO2
Carbon Emissions
Energy Type
Natural Gas
Oil Products
Coal
Synth etic Fuels
Carbon E mmissions
(Million Metric
Tons/Exajoule
13.74
19.94
24.12
40.00
Land-Use Change--CO2 Emissions
2000
1800
1600
1400
1200
1000
800
600
400
200
0
400.0
350.0
300.0
250.0
200.0
150.0
100.0
50.0
0.0
Land-Use Change & CH4
Emissions
Rice
Cultivation
Livestock
Organic matter + H2O
CO2 + CH4 + Nutrients
Methane emissions depend on:
Type of animal Cows and sheep
generate more methane than horses
& pigs
Diet dairy cows in developed nations
generate 2.5 times more methane
than similar cows in developing
nations (technology effect)
Livestock
125
100
75
50
25
1840 1860 1880 1900 1920 1940 1960 1980 2000
Termites
Biome
106 Termite/Acre
Tropical forest
Temperature forest
Savanna
Temperature grassland
Cultivated land
Desert scrub
12.80
2.43
17.81
8.66
11.38
0.93
Zimmerman et al., 1982 Science 218:563-565
Frasswer et al., 1986. Atmospheric Chemistry 4:295-310..
Emission
Rate
4.2 E-03
1.8E-03
8.0E-03
1.8E-03
1.8E-03
1.0E-03
Sulfur Emissions
80000
Anthropogenic Sulfur Emissions
70000
60000
50000
40000
30000
20000
10000
0
1850 1858 1866 1874 1882 1890 1898 1906 1914 1922 1930 1938 1946 1954 1962 1970 1978 1986 1994
Radiative Forcing of Sulfur Emissions
Direct Effect
The Heat Balance of Planet Earth
SOx
Ground
Indirect Effect
Formation of Cloud Nuclei
The Heat Balance of Planet Earth
SOx
Clouds
Ground
Climate Models: How, Where, and By
How Much Will Climate Change?
Climate Models
Track the flow of energy and water
Differ according to their spatial and temporal resolution
One Dimensional Climate Models
Solar radiation
Infrared radiation
Atmosphere
Heat exchange
Surface layer
upwelling
Deep Ocean
Diffusive mixing
upwelling
Two Dimensional Climate Models
General Circulation Models
Causes For Temperature Change
Doubling of radiative forcing……………1.2oC
Increased water vapor……….. ……….1.6oC
Increase in clouds………………………..0.8oC
Changes in surface albedo……………….0.4oC
Other changes……………………………0.2oC
Total change in temperature…………….4.2oC
Forecasts for Climate Change
More frequent extreme high temperatures and less
frequent extreme low temperatures.
Night-time low temperatures generally increase more
than daytime highs, reducing diurnal temperature range.
Decreased daily winter temperature variability and increased
summer variability in mid-latitude N hemisphere
Mid-continental summer drying due to precipitation not
keeping up with temperature & evaporation
Intensity of precipitation events increases.
Confidence in Model Predictions
Confidence
(latter 20th
century)
Likely
Very likely
Very likely
Likely, many N.
Hemis.
Likely, few
areas
Not observed
Changes in
Phenomenon
Confidence
(21st century)
Higher max
temps
Higher min
temps
Reduced diurnal
temps
More intense
precip.
Increased
summer drought
Very likely
Very likely
Very likely
Very likely,
many areas
Likely, most
mid-lat.
interiors
Increase cyclone Likely, some
wind intensity
areas
Detection: Is temperature Increasing?
Uncertainty in the Observational
Record
Changes in measurement instruments
Change from rural to urban
Changes in location of measurements
Melting Ice Shelves
There's no evidence
of any period in the
last 12,000 years
where there was
open water in the
area that has now
been exposed," Dr.
Scambos said.
New York Times March 20, 2002
Ice Shelf Break-Up
Jan 31 2002
Feb 17, 2002
The speed of it is
staggering," said Dr.
David Vaughan, a
glaciologist at the
British Antarctic
Survey.
New York Times March 20, 2002
Feb 23, 2002
March 5
Attribution: Are Humans Responsible
for Increased Global Temperatures?
General Circulation Models
Do increases in greenhouse gases and
anthropogenic sulfur emissions help GCM’s
simulate the historical temperature record
Control Scenario: Simulate model with
constant radiative forcing, but natural
variability
Anthropogenic: Simulate model with
greenhouse gases and sulfur emissions
Full Simulation: Simulate model with both
natural variability and anthropogenic activity
Experimental Results
Statistical Analysis of Historical Data
Emissions, Concentrations,
& Temperature
0.40
0.30
0.20
Degrees C
0.10
0.00
-0.10
-0.20
-0.30
-0.40
-0.50
-0.60
1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990
How Much Doubt Exists:
Fact or Fiction?
“If rising carbon dioxide is the cause of rising
temperatures, why didn’t it cause temperatures
to rise from 1940 to 1970?
“Trust me, the satellite data have been
reanalyzed dozens of times,…they show much
less warming than expected by theory
Remember Sulfur Aerosols!
2.5
2
1.5
Watts per Square Meter
Greenhouse Gases
1
Anthropogenic Forcing
0.5
0
1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990
-0.5
Sulfur Aerosols
-1
-1.5
Contamination
Satellite
Reconciliation
Fu et al., 2004 Nature 429:55-58
Climate change impacts on the
environment & economy
Change in Sea Level
Impact on agriculture
Impact on Biomes
Changes in Sea Level
Melting of Glaciers and Polar Ice
Thermal Expansion of Water
Melting
Glaciers
Qori Kalis glacier in Peru's
Quelccaya ice cap, Southern
Andes
NH Sea Ice Extent, 1901-98
Eastern US 11.8 Thousand Years Ago
Eastern US 5 Meter Sea Level Rise
Eastern US 50 Meter Sea Level Rise
Florida 11.8 Thousand Years Ago
Florida 5 Meter Sea Level Rise
Florida 50 Meter Sea Level Rise
Impacts on Agriculture
Benefits
Costs
Longer growing season
Mid Continent Drying
CO2 Fertilization
Warmer nights
Can Biomes Migrate in Time?
North
America
18,000 years ago
North
America
10,000 years ago
North
America
5,000 years ago
North
America
200 years ago
Climate Change & Extinction
Climate change scenarios
Changes in the area of biomes
Relation between area and species
Number of species that go extinct
Thomas et al, 2004 Nature 427:145-148.
Results
Climate change scenario
Migration rate
Minimum
Universal dispersal 9-13
No dispersal
22-31
Middle
High
15-20
26-37
21-32
38-52
What (If Anything) Should Be Done?
Should Anything be Done?
How much should emissions/concentrations
be reduced?
Should Anything Be Done?
Is society emitting the optimal level of greenhouse
gases and sulfur?
No Emitters do not pay for any of the
damage associated with global climate
change
How Much Should be Done
What information would society like to have ?
What is the economic value of the damage
(and benefits) associated with global
climate change?
What are the costs associated with
reducing emissions of greenhouse gases
and/or removing greenhouse gases from
the environment?
How To Deal With Uncertainty
Command and Control
Specific technology requirements
Emissions reduction fairly well known
Cost not well known
Market-Based Mechanisms
Carbon tax
Raise energy price relative to capital and labor
Raise coal and oil price relative to natural gas
Tradable Permits
Issue certificates that allow holder to emit CO2
The Kyoto Protocol