5.2 The Greenhouse Effect

Topic 5 – Ecology & Evolution

The Greenhouse Effect• 5.2.1 Draw and label a diagram of the carbon cycle to

show the processes involved.• The details of the carbon cycle should include the

interaction of living organisms and the biosphere through the processes of photosynthesis, cell respiration, fossilization and combustion. Recall of specific quantitative data is not required.

• TOK: What difference might it make to scientific work if nature were to be regarded as a machine, for example, as a clockwork mechanism, or as an organism, that is, the Gaia hypothesis? How useful are these metaphors?

The Greenhouse Effect• 5.2.2 Analyse the changes in concentration of

atmospheric carbon dioxide using historical records.• Data from the Mauna Loa, Hawaii, or Cape Grim,

Tasmania, monitoring stations may be used.

• 5.2.3 Explain the relationship between rises in concentrations of atmospheric carbon dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect.

The Greenhouse Effect• Students should be aware that the greenhouse effect is

a natural phenomenon. Reference should be made to transmission of incoming shorter-wave radiation and re-radiated longer-wave radiation. Knowledge that other gases, including methane and oxides of nitrogen, are greenhouse gases is expected.

The Greenhouse Effect• 5.2.4 Outline the precautionary principle. • The precautionary principle holds that, if the effects of a

human-induced change would be very large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding. This is the reverse of the normal situation, where those who are concerned about the change would have to prove that it will do harm in order to prevent such changes going ahead.

The Greenhouse Effect• TOK: Parallels could be drawn here between success in

deterring crime by increasing the severity of the punishment or by increasing the chance of detection. If the possible consequences of rapid global warming are devastating enough, preventive measures are justified even if it is far from certain that rapid global warming will result from current human activities.

The Greenhouse Effect• 5.2.5 Evaluate the precautionary principle as a

justification for strong action in response to the threats posed by the enhanced greenhouse effect.

• Aim 8: Consider whether the economic harm of measures taken now to limit global warming could be balanced against the potentially much greater harm for future generations of taking no action now. There are also ethical questions about whether the health and wealth of future human generations should be jeopardized, and whether it is right to knowingly damage the habitat of, and possibly drive to extinction, species other than humans.

The Greenhouse Effect• The environmental angle here is that the issue of global

warming is, by definition, a genuinely global one in terms of causes, consequences and remedies. Only through international cooperation will a solution be found. There is an inequality between those in the world who are contributing most to the problem and those who will be most harmed.

The Greenhouse Effect• 5.2.6 Outline the consequences of a global temperature

rise on arctic ecosystems.• Effects include increased rates of decomposition of

detritus previously trapped in permafrost, expansion of the range of habitats available to temperate species, loss of ice habitat, changes in distribution of prey species affecting higher trophic levels, and increased success of pest species, including pathogens.

Key processes in the Carbon cycle

• Combustion

• Cell respiration

• Photosynthesis

• Fossilisation

• Interaction between living organisms

The layers of the

atmosphereThe troposphere is the part of the atmosphere in the biosphere

The stratosphere contains the ozone layer

The stratosphere is also a zone of warm air that keeps a lid on the troposphere. It does not mix with the upper atmosphere

© Windows to the Universe© Text 2007 Paul Billiet ODWS

The Greenhouse Effect

• Earth has a natural greenhouse effect

• This is important to prevent large fluctuations in temperature

• Without a greenhouse effect on Earth, we would not have life as we know it.

Greenhouse Effect

Light from the sun has short wavelengths and can pass through most of the atmosphere.

This sunlight warms the Earth which in turn emits long wave radiation.

This long wave radiation is bounced back by the greenhouse gases, such as carbon dioxide, methane, CFCs, water vapour, and sulphur dioxide

The Greenhouse Effect

• The molecules of some gases in the atmosphere absorb heat energy and retain it

• This can be a good thing

• Without an atmosphere the Earth would have same temperature as the moon

• Moon mean surface temperature -46°C

• Moon temperature range: -233 to +123°C

© 2007 Paul Billiet ODWS

The Greenhouse Gases

• H2O vapour

• CO2

• CH4

• NOx

• CFC

© Oceanworld 2005 Robert R Stewart

© Text 2007 Paul Billiet ODWS

The Greenhouse Gases• Water vapour in the atmosphere is stable

• The atmosphere is saturated

• CO2 levels are currently rising

• They have varied in the past

• Methane levels are increasing:as more cattle are farmed, as more paddy fields are planted, as permafrost melts

• NOx levels increase due to increased circulation of motor vehicles

© 2007 Paul Billiet ODWS

Mauna Loa Observatory

© Mauna Loa Observatory Site

© Earth System Research Laboratory

© Earth System Research Laboratory

Carbon dioxide a greenhouse gas

© Mauna Loa Observatory Site

South Pole Data

Samoa data

© Australian Antarctic Division

© New Scientist : Environment

Levels during the last ice age

© Dennis Hartmann: Universoty of Washington: Department of Atmospheric Sciences

Out of the ice age

Since the Industrial Revolution

Concentration of Carbon Dioxide from trapped air measurements for the DE08 ice core near the summit of Law Dome, Antarctica. (Data measured by CSIRO Division of Atmospheric Research from ice cores supplied by Australian Antarctic Division)

Is it really getting warmer

1979 2003

© NASA

5.2 The ENHANCED greenhouse effect

Phenomenon

The mean global temperature has risen about 1 degree Celsius since 1856. We saw an increase between 1910 and 1940, and from 1970 onwards.

5.2 Enhancing the greenhouse Effect

Human Activities• Increased burning of fossil fuels releasing greenhouse

gases (CO2, oxides of Nitrogen)

• Deforestation – less trees to convert CO2 back to O2

• Raising cattle and paddy fields release methane• CFCs were used as a propellant in aerosols and as a

coolant in refrigerators, freezers and air conditioning units. Old cooling machinery can still leak CFCs and need to be disposed of carefully – CFCs are persistent

• Other industrial activities that release other greenhouse gases

The Precautionary Principle

• The precautionary principle holds that, if the effects of a human-induced change would be very large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding.

• This is the reverse of the normal situation where those who are concerned about the change would have to prove that it will do harm in order to prevent such changes going ahead.

Evaluate the precautionary principle…

• …..as a justification for strong action in response to the threats posed by the enhanced greenhouse effect

• Economic harm Vs harm to environment for future generations

• Should the health and wealth of future generations be jeapardised?

• Is it right to knowingly damage the habitat of species other than humans? Cause extinction?

• Need for international cooperation• Inequality between those contributing most to the harm,

and those who will be most harmed

The consequences• Sea level rise

Changing sea ice... • Flooding coastal areas

Reduced agricultural landDisplacement of populations

• Climate change and changing weather patterns

• Displacement of ecosystemsChange in range of insect vectors of pathogensReduced biodiversity

© 2007 Paul Billiet ODWS

The consequences

• Increased rates of photosynthesis

• Increased agricultural production at high latitudes

• BUT faster growth means: less protein in cerealstrees taller and more exposed to storm damage

© 2007 Paul Billiet ODWS

Knock-on effects• Increased temperature melts the permafrost• Frozen plant remains decompose• More methane released• Similarly soils will lose organic carbon (humus)

more rapidly in a warmer climate• Ice caps melt more sea exposed• Snow reflects light (high albedo)• Water absorbs light, increases warming• More CO2 dissolving in water lowers pH• Currently this is buffered and remains stable• Eventually pH will drop sea life will die CO2

produced as organisms decompose© 2007 Paul Billiet ODWS

What can be done?Reduce carbon emissions• Improve mass transport systems (public transport)• Design more efficient motors• Design alternative power sources• Hydrogen powered motors

BUT problems of fuel reservoir, delivery, fabrication

• Renewable energy (wind, tidal, hydro, geothermal, biomass)BUT growing crops for biofuel reduces farmland available for foodHydroelectric dams disrupt river ecosystems

• Nuclear powerBUT problems of nuclear waste treatment/storage© 2007 Paul Billiet ODWS

What can be done?

Increase natural CO2 sequestering

• Reduce deforestation

• Increase reforestation

© 2007 Paul Billiet ODWS

What can be done?

Artificial CO2 sequestering

• Filter CO2 sources using hydroxide scrubbers

• Injection of CO2 into deep ocean layersForms CO2 reservoirsImpact on sea life unknown

• Injecting CO2 into disused oil wells

• Mineral deposition as carbonates© 2007 Paul Billiet ODWS

The bottom lineTwo factors will ultimately govern what happens:1. Human population growth

More people means greater demand for non-renewable resources

2. The ecological footprint of each individual humanHigher standards of living usually means higher consumption of fossil fuels

The planet will look after itself in the endThere are plenty of examples where human

communities have disappeared because they outstripped the environmental resources

© 2007 Paul Billiet ODWS

The planet will look after itself in the end

• Easter Island (Rapanui) in the Pacific

• Settled between AD900 and 1200

• Community in severe decline AD 1700

• Cause: excessive deforestation

© Text 2007 Paul Billiet ODWS

The Moai statues, Easter Island © Martin Gray, World Mysteries

The planet will look after itself in the end

• Chaco Canyon, New Mexico

• Anasazi culture • AD 850 – 1250• Cause: Deforestation

combined with a decline in rainfall

© New Mexico Tourism Department

© Text 2007 Paul Billiet ODWS

The planet will look after itself in the end

• Mesopotamia• Sumerian civilization• 3100 – 1200 BC • Increased salt levels

in soil due to irrigation systems & arid environment

• Reduced food yield

© Text 2007 Paul Billiet ODWS

© Asociación Cultural Nueva Acrópolis en Barcelona

The planet will look after itself in the end

• Greenland• Viking colony• AD982 – 1350• Cause: Deforestation,

soil degradation & cooling of the climate

© Emporia State University

© Text 2007 Paul Billiet ODWS

forumpolitics.com/pics/earth-photo.jpg

Who’s next?

© NASA

5.2 The Greenhouse Effect

The IBO assessment statements:

The Greenhouse Effect• 5.2.1 Draw and label a diagram of the carbon cycle to

show the processes involved.• The details of the carbon cycle should include the

interaction of living organisms and the biosphere through the processes of photosynthesis, cell respiration, fossilization and combustion. Recall of specific quantitative data is not required.

• TOK: What difference might it make to scientific work if nature were to be regarded as a machine, for example, as a clockwork mechanism, or as an organism, that is, the Gaia hypothesis? How useful are these metaphors?

The Greenhouse Effect• 5.2.2 Analyse the changes in concentration of

atmospheric carbon dioxide using historical records.• Data from the Mauna Loa, Hawaii, or Cape Grim,

Tasmania, monitoring stations may be used.

• 5.2.3 Explain the relationship between rises in concentrations of atmospheric carbon dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect.

The Greenhouse Effect• Students should be aware that the greenhouse effect is

a natural phenomenon. Reference should be made to transmission of incoming shorter-wave radiation and re-radiated longer-wave radiation. Knowledge that other gases, including methane and oxides of nitrogen, are greenhouse gases is expected.

The Greenhouse Effect• 5.2.4 Outline the precautionary principle. • The precautionary principle holds that, if the effects of a

human-induced change would be very large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding. This is the reverse of the normal situation, where those who are concerned about the change would have to prove that it will do harm in order to prevent such changes going ahead.

The Greenhouse Effect• TOK: Parallels could be drawn here between success in

deterring crime by increasing the severity of the punishment or by increasing the chance of detection. If the possible consequences of rapid global warming are devastating enough, preventive measures are justified even if it is far from certain that rapid global warming will result from current human activities.

The Greenhouse Effect• 5.2.5 Evaluate the precautionary principle as a

justification for strong action in response to the threats posed by the enhanced greenhouse effect.

• Aim 8: Consider whether the economic harm of measures taken now to limit global warming could be balanced against the potentially much greater harm for future generations of taking no action now. There are also ethical questions about whether the health and wealth of future human generations should be jeopardized, and whether it is right to knowingly damage the habitat of, and possibly drive to extinction, species other than humans.

The Greenhouse Effect• The environmental angle here is that the issue of global

warming is, by definition, a genuinely global one in terms of causes, consequences and remedies. Only through international cooperation will a solution be found. There is an inequality between those in the world who are contributing most to the problem and those who will be most harmed.

The Greenhouse Effect• 5.2.6 Outline the consequences of a global temperature

rise on arctic ecosystems.• Effects include increased rates of decomposition of

detritus previously trapped in permafrost, expansion of the range of habitats available to temperate species, loss of ice habitat, changes in distribution of prey species affecting higher trophic levels, and increased success of pest species, including pathogens.