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.

Movie

http://www.climatecrisis.net

96 mins

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.