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Transcript 
Global Climate Change
Samayaluca Dune Field, south of Juarez, Chihuahua
Climate vs. Weather
NMSU Rainfall
10
9
Cumulative Rainfall (Inches)
8
7
6
2006
2005
2004
2003
5
4
3
2
1
0
-1
1
20
39
58
77
96 115 134 153 172 191 210 229 248 267 286 305 324 343 362
Days since Jan 1
120
100
# Days
80
over 100
over 95
over 90
60
40
20
0
2006
2005
2004
2003
Average
120
Days since Jan 1
100
80
Temp
2006
2005
2004
2003
60
40
20
0
1
20
39 58 77 96 115 134 153 172 191 210 229 248 267 286 305 324 343 362
Max Temp. (°F)
Days since Jan 1
Climate System: 5 parts
•
•
•
•
•
Atmosphere
Ocean
Cryosphere (ice)
Lithosphere
Sun and internal earth heating
Climate System
• Atmosphere
–
–
–
–
–
Nitrogen
N2
78%
Oxygen
O2
21%
Argon
Ar
0.93%
Carbon dioxide
CO2
0.035%
Other minor gases
0.035%
Ocean influences climate
Transfers of heat from tropics to polar regions
(i.e., Gulf Stream)
Cryosphere: ICE
• Melting ice increases ocean volume
• Sea level was 130 m (425 feet) lower during last ice
age (18,000 years ago)
• Ice reflects solar energy: albedo
What is albedo?
• Reflectance of land surface
• Earth reflects about 31% of solar energy
Lithosphere
• Mountains influence weather
• Arrangement of continents affects ocean
currrents
• Volcanism affects composition of
atmosphere
Heat flowing out of Earth’s
deep interior is only 0.06 W/m2.
Solar energy input to
Earth’s surface is
342 W/m2.
Greenhouse Gases
• CO2, H20 and methane (CH4):
• Absorb and re-radiate radiation
• Insulates and raises Earth temperature
Earth Temperature
Normal:
14o C (57o F)
Without greenhouse gases:
-19o C (-2o F)
Feedback enhances warming
• Positive Feedback:
– Amplifies changes in the system.
– Temperature increase decreases Earth’s albedo
by reducing snow and ice cover
Climate Change
Understanding Natural Climate
Variability:
Use the geologic record to understand Earth
Climate in the past
(Uniformitarianism)
Long-term change can be
assessed from ice cores,
which record annual cycles
of ice formation from snow.
* Cycles can be counted back
like tree rings to create a long
term record.
* Ice layers trap atmospheric
gas, contain isotopic record of
temperature change.
Milankovitch cycles
Related to variations in:
1. Eccentricity
2. Tilt of axis
3. Precession (wobble)
High eccentricity increases contrast between summer and winter.
Earth’s tilt axis changes over time
Precession
1941
2004
Columbia glacier
Greenland
Greenland
What causes sea level rise?
Melting ice
Hotter oceans are larger volume
Sea Level Rise
Barrier Islands
Sea-Level Rise
1 meter rise
2 meter rise
4 meter rise
8 meter rise
The influence of Carbon on climate change
ATMOSPHERE
Fossilfuel
burning
(5.3 Gt/yr)
Land-use
change:
deforestation,
agriculture
(1.7 Gt/yr)
Land uptake
By new plant
growth
(1.9 Gt/yr)
Terrestrial biosphere
LAND
Cement production (0.1 Gt/yr)
Fossil
Rock
organic
carbonates
carbon
GEOLOGIC RESERVOIRS
Ocean uptake
by air-sea gas
exchange
(1.9 Gt/yr)
OCEAN
Human activities release
a total of 7.1 Gt of carbon
into the atmosphere each
year.
New plant growth and
air-sea gas exchange
remove 3.8 Gt/yr,…
ATMOSPHERE
Fossilfuel
burning
(5.3 Gt/yr)
Land-use
change:
deforestation,
agriculture
(1.7 Gt/yr)
Land uptake
By new plant
growth
(1.9 Gt/yr)
Terrestrial biosphere
LAND
Cement production (0.1 Gt/yr)
Fossil
Rock
organic
carbonates
carbon
GEOLOGIC RESERVOIRS
Ocean uptake
by air-sea gas
exchange
(1.9 Gt/yr)
OCEAN
…yielding a net
atmospheric
increase of
3.3 Gt/yr.
Climate has been
relatively warm and
stable during the last
10,000 years.
High
Key:
Temperature
CO2
Methane
Thousands of years before present
Relative carbon dioxide and
methane concentrations
Temperature relative to present climate (°C)
There is a decline in both
temperature and greenhouse
gas concentrations during
glacial periods…
…and a rapid
rise during
deglaciation.
Low
East Antarctic
ice core data
Interglacial epoch
Glacial epoch
Is Human-induced
climate change
possible?
CO2 concentration (ppm)
Northern Hemisphere temperature
anomaly (°C)
The 20th-century is clearly
anomalous when compared
with the last millennium.
Temperature
CO2 concentration
Years
Temperature
CO2
concentration
Years
CO2 concentration (ppm)
Global temperature anomaly (°C)
A recent warming trend correlates
with the increase in CO2.
Atmospheric CO2 Projections Under 3 Alternate Scenarios….
2000
2020
2040
2060
Year
2080
2100
….and Estimated Average Surface Temperatures for Those Scenarios
Uncertainty envelope due to
lack of knowledge of
climate system
Global Warming Evidence
Global Warming Evidence
Is Global Warming Real?
• 20 years of data:
Is Global Warming Real?
• 130 years of data:
Why is Global Warming ignored?
• Not enough evidence?
• Better things to spend money on?
• Cutting emissions will hurt the economy
• The EFECTS of climate change might be
distant and uncertain
• The COSTS of curbing greenhouse gases
are immediate and substantial!
Global Warming
• Small steps can reduce carbon emissions
• These are affordable and multiplied by
100,000,000s of people can be significant
•
•
•
•
•
•
CO2 is a small part of the atmosphere
Small increases have huge effects
Greenhouse gases keep earth hot
Natural changes in climate occur
Recent changes correlate to human activity
Changes in lifestyle can avoid catastrophe
Keeling Curve
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