Transcript 5.2: The Greenhouse Effect - bio

5.2: The Greenhouse
Effect
Topic 5: Ecology & Evolution
Miss Friedman
5.2.1: The Carbon Cycle
► Carbon
is one of the 4 main elements found
in all organic molecules including
carbohydrates, lipids and proteins
► Carbon is found in one of four “pools”
►Biosphere
►Oceans
►Atmosphere
►Sediments
5.2.1: The carbon cycle
► Carbon
is moved between these four pools
by a variety of biological, geochemical &
industrial processes
►Photosynthesis
►Respiration
►Feeding
►Fossilization
►Combustion
5.2.2: Historical Records
► Trends
in atmospheric gases are studied as
indicators of potential climate change
► Carbon dioxide has been monitored at
Mauna Ioa atmospheric laboratory on
Hawaii since 1958
► The basic trend is an increase in
atmospheric carbon dioxide levels
•Carbon dioxide concentration has increase since 1960 from around 315 ppm
to 380 ppm
•Graph is not smooth but goes up and down to reflect changes in the amount of
atmospheric carbon dioxide due to the seasons
•Autumn leaves drop & plants no longer take up CO2
•Spring when plants start to photosynthesize CO2 levels drop
5.2.3: Atmospheric gases &
enhanced greenhouse effect
Greenhouse effect
A natural process that creates moderate
temperatures on earth to which life has
adapted.
Earth is about 30oC warmer than it would be
without any greenhouse gases in the
environment. This is needed to sustain life
on earth.
5.2.3: continued
Enhanced greenhouse effect
The concern that the activities of humans may
be increasing the levels of carbon dioxide
and other greenhouse gases (methane,
oxides of nitrogen) in the atmosphere.
This may lead to increased global
temperatures and climate change.
•Increase in carbon dioxide and other greenhouse gases will increase
particles in atmosphere
•More infra-red will be absorbed, scattered and retained as heat
•Average global temperature will rise
5.2.4: The precautionary
principle
► The
concept that someone wishing to take a
certain kind of action should prove that the action
does not cause serious or irreversible harm to the
public if there is no scientific consensus about the
outcome of the action.
► Both the European Union and the United
Nations have adopted the principle as a
foundation for some policies
► Montreal
protocol (1987)
► Rio Declaration (1992)
► Maastricht Treaty (1993)
5.2.4: continued
► Read
the article
http://en.wikipedia.org/wiki/Precautionary_principle
► Read
the Policy document from the UK
Heath and Safety Executive
http://www.hse.gov.uk/aboutus/meetings/committees/ilgra/pppa.htm
► Read
the TOK link in your textbook pg. 82
5.2.5: Precautionary principle &
the greenhouse effect
► Since
scientist cannot agree on the exact
effects of increasing levels of carbon
dioxide, the precautionary principle should
be applied
► Countries could agree to reduce greenhouse
emissions and boycott trade with countries
that do not comply
► However, in poor countries it may not be
possible to reduce greenhouse emissions
without delaying economic growth
5.2.5: continued
Why can’t scientist know what problems
the Greenhouse effect will cause?
► Climate
is a complex phenomena with many
emergent properties often based on time
frames beyond the human experience. This
makes predictions of location and timing
difficult.
5.2.5: continued
However, it is possible to hypothesize about
the general effects:
► Increased frequency and intensity of droughts
► Flooding as a result of higher rainfalls, increased
snowmelts and rising sea levels
► Decline in food production
► Increased disease (pathogens survive better in
colder temperatures)
► More extreme weather
► Loss of biodiversity
5.2.6: Greenhouse effect & the
artic ecosystem
► As
global temperatures rise, many
ecosystems would be affected but the artic
ecosystem would show clearly visible
changes
► The average artic region temperature is
rising at twice the speed of the rest of the
world
Negative Effects
► Melting
permafrost in Siberia would release more
methane (a greenhouse gas)
► Species, like caribou, polar bears, seals, are
changing their migration pattern to respond in
changes to their feeding patterns
► Native people are finding it harder to hunt
► Villages move as environment becomes a swamp
due to permafrost disappearing
► Polar bears hibernate less as temperature rises.
Must swim further and more often to reach
prey/destination which uses more energy
► Biodiversity could change and herbivore animals
would need to change their eating patterns
Positive Effects
► Milder
climate would enable other species to
survive in Artic (though competition could
lead to extinction of other plant species)
► Plant productivity would increase
biodiversity in the area