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Environmental Science
Unit 2 – Climate Change
(STE Chapter 12, pp. 253-268)
(STE Chapter 2, pp. 26-27)
Where are we going?
- Composition of the Atmosphere
- The Greenhouse Effect
- Keeling Curve
- Sources
- Consequences of a Warmer World
- Sea Level Rise
- Temperature Records
- Where are we now?
- Solutions
Atmospheric
Greenhouse Effect
Greenhouse gases?
The Atmosphere
Moelcular Models
Build and draw models of
the atmospheric gases
Red = O
Blue = N
Black = C
White = H
Atmospheric Composition
Permanent
Variable
Question
Complete the following table:
Gas
% (by vol)
Importance
N2
78
N-cycle
Oxygen
O2
21
Respiration
Argon
Ar
1
Inert
Water vapor
0-4
GH + Heat transport
Carbon Dioxide
H2O
CO2
0.04
GH + photosynthesis
Methane
CH4
0.00017
GH gas
Nitrous oxide
N2O
0.00003
GH gas
Ozone
O3
0.000004
Protection from UV
Particles/aerosols
NA
0.000001
Energy budget
Nitrogen
Symbol
No. 1 Greenhouse Gas
% = pph = ppm / 10,000
ppm / 10,000
0.0350 = 350/10,000
Mean surface
T = 15 ºC
Question
If water vapor is the #1 greenhouse gas why don’t
we worry about it?
Because it is thought that we can do little to alter its
concentration in the atmosphere.
Experiment: GH in a Jar
• Design an experiment to
show the GH effect
What is Radiation?
• What is radiation - electromagnetic waves?
• Characteristics of a wave…
• Q: What are typical wavelengths of radiation??
Comparitively Speaking…
Visible = SW
Infrared = LW
Energy
Consider IR, UV and VIS radiation:
1. Arrange them in order of inc. wavelength
2. Arrange them in order of increasing energy
3. How are these arrangements related to the Sun’s ability to heat a
closed car?
What is the Greenhouse Effect?
SW in
LW out
Absorption by gases
Re-emission of LW by gases
http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/
Animation
http://news.bbc.co.uk/2/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm
Animation
The Analogy
• How is the atmospheric
greenhouse effect different to a
regular greenhouse?
• Heat is not ‘trapped’, and the
atmosphere does not act like a
‘blanket’…why?
There is circulation of air in the atmosphere,
no circulation in a regular glass
greenhouse.
Blankets prevent convection.
Why are CO2 and H2O GH Gases Whilst O2
and N2 are not?
• They can vibrate – stretch and bend
Movie
End
• Review
Evidence for Global Warming
Arrhenius
First proposed by
Arrhenius in 1896
Arrenhius predicted effect
would be seen in 3000
years
Evidence for Global Warming
Keeling Curve
1958: Keeling began
measuring CO2 at
Mauna Loa, HI
Movie
Evidence for Global Warming
Keeling Curve
• What is the significance of the Keeling curve?
What could be
responsible for
this seasonal
up-down
fluctuation?
Since 1958
atmospheric
carbon dioxide has
risen by more than
15%
http://www.cmdl.noaa.gov/ccgg/index.html
Evidence for Global Warming
Global Warming
• What is it?
• An enhanced atmospheric
greenhouse effect due to
man-made pollutants
Concentration of Energy Consumption
Angola major oil
producing country
(3 cities)
China and India are electrifying
like crazy, much larger impact
than US in next 50 yrs
Sources of GH Gases
• Carbon dioxide (CO2)
– > 380 ppm
– Rising
– From fossil fuels
– Deforestation
Surprised not only by
increase but by rate of
increase
Keeling curve again
More Sources
• Methane (CH4)
– Agriculture
– Rice paddies
• Nitrous oxide (N2O)
– Agriculture
Global Warming Potential
•
Global warming potential (GWP) is measured relative to CO2
- Methane x 21
- Nitrous oxide x 270
- CFC’s x 140-12000
•
Much LARGER INPUT of CO2
makes it the most important greenhouse gas.
Movie
96 mins
http://www.climatecrisis.net
End
• Review
Further Evidence for Global Warming
Temp change
• Many groups have been working on compositing and quality
control the instrumental data set for the globe
• Thousands of sites
– Record is short
– Biased towards W Europe and E US
Data
Direct records
How do we take the
Earth’s temperature?
Proxy (indirect)
records
Temperature has fluctuated
Ice Cores
• Bubbles of trapped air
between snowflakes
– How is it dated?
– How do we find
temperature?
Temperature has fluctuated
Cooling and Warming
•
•
Normal oxygen 16O: contains 8 p+, 8 n
18O: contain 8 p+, 10n
– this is an isotope of oxygen and is
heavier than 16O
•
Isotope fractionation:
– 16O evaporates more readily than 18O
since it is lighter
•
Warm period, the relative amount of 18O will
increase
Carbon Dioxide Levels
420
Muana Loa Readings
CO2 Levels Since 1958
CO2 (ppm)
CO2 (ppm)
370
320
370
350
330
310
40
30
20
10
0
270
220
170
Dome Concordia
600000
Vostok Ice Core
400000
Time (YBP)
200000
0
Temperature has fluctuated
Cooling and Warming
•
Natural?
– Volcanoes
– Milankovich cycles
– Solar activity
• Man-made? Trace gases
• Combination of both?
– Increase in last 1000 yrs
Temperature has fluctuated
Vostok – ancient atmospheres
•
•
•
•
Furthest point from coastline, coldest
place on earth -126 ºF
Vostok pretty grim existence, largest
graveyard by far
End of last ice age about 10,000 yr BP
4 cycles most of the time either in an ice
age or getting to one, warm conditions
are rare (5% of time) abrupt changes
Sensitvity - 80 ppm in CO2 produces
a 10 ºC change at Vostok
Lead lag issue, CO2 first then T, or
otherway around
“Hockey Stick” Controversey
Temperature Change (°C)
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
Last 1000 Years – N. Hemisphere
1980+ Above
baseline
Controversial ‘Hockey Stick’
Graph
Zero-point is arbitrarily
set at average
temperature of the
globe between 19601990
Error envelope
Small natural variability
Natural cooling trend,
sudden warming
exceeds error envelope
Arctic Climate Impact Assessment
IPCC
Climate Changes During Past 400,000 Years
Past climate based on study of
Antarctic glaciers
Cycles of Ice Ages lasting about
100,000 years
Interglacial Periods lasting 10,000 to
12,500 yrs
Temperature has fluctuated
• Now in warm interglacial
period
• Correlation between CO2 &
mean temperature
Not totally 1:1 correlation –
tells us something about the
complexity of the system
Evidence of Warming
•
•
•
The 20th century was the hottest century in the past 1000 years.
Mean global temperature rose about 0.6º C (1º F) in past 100 years
During the last century, the world’s sea level rose by 10-20 cm, mostly due to runoff
from melting and land-based ice and the expansion of ocean water as temperatures
rise
Arctic
• Over the past 50 years, Arctic temperatures have risen almost twice as fast as those
in the rest of the world
– Glaciers and floating sea ice are melting and shrinking at increasing rates
– Arctic as is most dramatic example of large changes Illustrates what all climate
models show
– ‘Polar amplification’
– Earth warms or cools more dramatically at both poles
– Canary in coal mine
Greenland – surface summer melting 80%
• >3 C ice will melt, glacial melt
End
• Review
Consequences of a Warmer World
• What will happen?
Sun
Troposphere
Greenhouse
gases
Aerosols
Warming
from
decrease
Cooling
from
increase
CO2 removal
by plants and
soil organisms
CO2 emissions
from land
cleaning, fires,
and decay
Heat and
CO2 removal
Heat and
CO2 emissions
Ice and snow cover
Shallow ocean
Land and soil biotoa
Long-term
storage
Natural and human emissions
Simplified model of major
processes that interact to
determine the average temperature
and greenhouse gas content of the
troposphere
Deep ocean
Stepped Art
Consequences of a Warmer World
•
•
•
•
•
•
Sea level rise, erosion
Weather extremes, heat waves
Loss of biodiversity, extinction
Drought, flooding, water stress
Loss of forests
Agricultural yield decrease
Movie
•
•
•
•
CNN Global Warming Effects
CNN Rising Global temperatures
ABC Global Warming
ABC Alaska Adventure
Consequences of a Warmer World
Feedbacks
• Some factors can amplify (positive feedback) and some can dampen
(negative feedback) projected global warming
• There is uncertainty about how much CO2 and heat the oceans can
remove from the troposphere and how long the heat and CO2 might
remain there
• Warmer temperatures create more clouds that could warm or cool
the troposphere
Consequences of a Warmer World
Sinks
•
Increased CO2 in the troposphere can increase plant photosynthesis (PS)
but:
– The increase in PS would slow as the plants reach maturity.
– Carbon stored by the plants would be returned to the atmosphere as
CO2 when the plants die.
– Increased PS decreases the amount of carbon stored in the soil.
– Tree growth may temporarily slow CO2 emissions in the S. Hemisphere
but is likely to increase CO2 emissions in the N. Hemisphere.
– Movie – Forests and GW
Consequences of a Warmer World
Sea Level Rise
ABC – Melting Ice
Between 1979 and 2005, average Arctic sea ice dropped 20%
(as shown in blue hues above).
Consequences of a Warmer World
Sea Level Rise
Consequences of a Warmer World
Sea Level Rise
•
Worst possible scenario: mass
flooding in low lying areas e.g.
islands (cf. Maldives)
•
CNN Movie
•
Due to thermal expansion of water
more than glacier melt
•
All coastline cities, and river deltas
e.g. Bangladesh, Pakistan, China,
Egypt, Florida, Louisiana and
other parts of the U.S
5m, 17 ft
Ice Cube Demo
•
•
•
•
Put some ice cubes in a glass
Record the volume
Wait for the ice to melt
Record the new volume
•
Is there a difference? What has this got to do with GW?
Consequences of a Warmer World
Changing Ocean Currents
• Storage of CO2 in deep
water (x50)
• Warming could decrease
ability of ocean to serve
as “sink” for carbon
– Loss of phytoplankton
• Positive feedback effect
• Increased warming
• Effects on the weather?
Thermohaline conveyer
Consequences of a Warmer World
Effects on Biodiversity
• Ecological Implications:
• Shift of habitat to higher
latitudes
• Shift of habitat to higher
elevations
• Potential large loss of
biodiversity
Consequences of a Warmer World
Agricultural Yield
• In a warmer world, agricultural productivity may
increase in some areas and decrease in others.
• Crop and fish production in some areas could be
reduced by rising sea levels that would flood river
deltas.
• Global warming will increase deaths from:
– Heat and disruption of food supply.
– Spread of tropical diseases to temperate regions.
– Increase the number of environmental refugees.
Future Scenarios
Global Climate Models
Projected warming of
1 to 3.5 º C between
1990 & 2100
Likely scenario:
x2 CO2 (from 280
ppm to 560 ppm)
before 2100
leading to
warming of 2º C
IPCC
End
• Review
Solutions to
Global Warming
Solutions to Global Warming
•
Climate change is such a difficult problem to deal with because:
– The problem is global
– The effects will last a long time
– The problem is a long-term political issue
– The harmful and beneficial impacts of climate change are not spread
evenly
– Many actions that might reduce the threat are controversial because
they can impact economies and lifestyles
Solutions to Global
Warming
Two ways to deal with
global warming
Solutions to Global Warming
Solutions
• Sequester
– Land
– Ocean
Solutions
• Governments can tax greenhouse gas emissions and energy
use, increase subsidies and tax breaks for saving energy, and
decrease subsidies and tax breaks for fossil fuels
• A crash program to slow and adapt to global warming now is
very likely to cost less than waiting and having to deal with its
harmful effects later
Solutions: International Climate
Negotiations: The Kyoto Protocol
• Treaty on global warming which first phase went into effect
January, 2005 with 189 countries participating
• It requires 38 participating developed countries to cut their
emissions of CO2, CH4, and N2O to 5.2% below their 1990
levels by 2012
• Developing countries were excluded.
– The U.S. did not sign, but California and Maine are
participating.
– U.S. did not sign because developing countries such as
China, India and Brazil were excluded
Beyond the Kyoto Protocol
• Countries could work together to develop a new international
approach to slowing global warming.
– The Kyoto Protocol will have little effect on future global
warming without support and action by the U.S., China,
and India
Individual Action
•
In 2005, the EU proposed a plan to reduce CO2 levels by 1/3rd by
2020
•
California has adopted a goal of reducing its greenhouse gas
emission to 1990 levels by 2020, and 80% below by 2050
•
Global companies (BP, IBM, Toyota) have established targets to
reduce their greenhouse emissions 10-65% to 1990 levels by 2010
•
Carbon Offsets (movie)
Develop crops that
need less water
Waste less water
Connect wildlife
reserves with corridors
Move hazardous material
storage tanks away
from coast
Move people away
from low-lying
coastal areas
Stockpile 1- to 5-year
supply of key foods
Expand existing
wildlife reserves
toward poles
Prohibit new construction
on low-lying coastal areas
or build houses on stilts
Education
http://www.panda.org/campaign/powerswitch/take_action/
switchemoff.cfm
Education
• Latest news
• Is not so good
News paper stories
• Russia ratifies Kyoto Protocol
• Michael Howard said ‘the UK must lead on Climate Change’, Blair’s
dire warning on climate change ‘what is now plain is that the
emission of greenhouse gases is causing global warming at a rate
that is simply unsustainabe in the long-term, and by long-term I do
not mean centuries ahead, I mean within the lifetime of my children
certainly and possibly my own…and by unsustainable I do not mean
a phenonemon causing problems of adjustment, I mean a challenge
so far reaching that its impact is so far reaching in its destructive
power that it changes radically human existence
• 7/03: US Senator Inhoffe senate hearing – with all this hysteria, all of
the fear, all of the funny science could it be that manmade GW may
be the greatest hoax ever perpetrated on the American people, it
sure sounds like it.