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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
The AtmosphereAtmospheric Greenhouse Effect
Greenhouse gases?
Moelcular Models
Build and draw models of the atmospheric gases
Red = O
Blue = N
Black = C
White = H
Atmospheric Composition
Permanent Variable
QuestionComplete the following table:
Gas Symbol % (by vol) Importance
N2 78 N-cycle
Oxygen 21
Ar 1 Inert
Water vapor 0-4 GH + Heat transport
CO2 0.04 GH + photosynthesis
Methane 0.00017 GH gas
Nitrous oxide N2O 0.00003
O3 0.000004
Particles/aerosols NA 0.000001 Energy budget
Nitrogen
Respiration
Argon
Carbon Dioxide
CH4
Ozone
GH gas
Protection from UV
O2
H2O
No. 1 Greenhouse GasMean surface T = 15 ºC
% = pph = ppm / 10,000ppm / 10,0000.0350 = 350/10,000
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…
Infrared = LW
Visible = SW
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 WarmingArrhenius
First proposed by Arrhenius in 1896
Arrenhius predicted effect would be seen in 3000 years
Evidence for Global WarmingKeeling 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
Keeling curve again
Surprised not only by increase but by rate of increase
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.
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
How do we take the Earth’s temperature?
Proxy (indirect)records
Direct records
Temperature has fluctuatedIce Cores
• Bubbles of trapped air between snowflakes– How is it dated?– How do we find
temperature?
Temperature has fluctuatedCooling 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
170
220
270
320
370
420
200000400000600000
Time (YBP)
CO
2 (p
pm
)
Vostok Ice CoreDome Concordia
Carbon Dioxide Levels
0
Muana Loa Readings
CO2 Levels Since 1958
310
330
350
370
10203040
CO
2 (p
pm
)
0
Temperature has fluctuatedCooling 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 VostokLead lag issue, CO2 first then T, or otherway around
“Hockey Stick” Controversey
1000 1200 1400 1600 1800 2000-0.8
Year
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
Te
mp
era
ture
Ch
an
ge
(°C
)
Direct temperature measurementsMann et al. 1999
Last 1000 Years – N. HemisphereControversial ‘Hockey Stick’ Graph
IPCCArctic Climate Impact Assessment
Zero-point is arbitrarily set at average temperature of the globe between 1960-1990
1980+ Above baseline
Error envelope
Small natural variability
Natural cooling trend, sudden warming exceeds error envelope
Climate Changes During Past 400,000 Years
Past climate based on study of Antarctic glaciersCycles of Ice Ages lasting about 100,000 yearsInterglacial 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
Stepped Art
Aerosols
Greenhousegases
Warmingfrom
decrease
Cooling from
increase
CO2 removal by plants and
soil organisms
CO2 emissions from land
cleaning, fires, and decay
Heat andCO2 removal
Heat andCO2 emissions
Ice and snow cover
Natural and human emissions
Land and soil biotoa
Long-termstorage
Deep ocean
Shallow ocean
Troposphere
Simplified model of major processes that interact to determine the average temperature and greenhouse gas content of the troposphere
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 WorldFeedbacks
• 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 WorldSinks
• 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
Between 1979 and 2005, average Arctic sea ice dropped 20% (as shown in blue hues above).
ABC – Melting Ice
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 ScenariosGlobal Climate Models
IPCC
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
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)
Move hazardous material storage tanks away
from coast
Connect wildlifereserves with corridors
Develop crops thatneed less water
Waste less water
Move people awayfrom low-lyingcoastal areas
Stockpile 1- to 5-yearsupply of key foods
Expand existingwildlife reserves
toward poles
Prohibit new constructionon low-lying coastal areasor 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.