Download Greenhouse Effect - hs science @ cchs

Climate Change
• Weather vs. Climate
• Earth’s energy supply
• The atmosphere
• Greenhouse gases
• The greenhouse effect
• Enhanced greenhouse effect
• The role of the carbon cycle
• Effects of global warming
• Historic climate change
• Climate proxies
• What you can do
Weather vs. Climate
Weather: atmospheric conditions, including
temperature, precipitation, wind, and humidity,
in a particular location over a short period of
time, such as a day or a week
Climate: the average of the weather in a region
over a long period of time
Air Convection Currents
• Large convection air currents occur over the
world because cool air is more dense than
warm air.
• These convection currents
can greatly affect the
weather in a given region.
Air Currents and Large Bodies of Water
• During the summer, large bodies
of water absorb a lot of heat
– This will cause the climate to be
more moderate in summer near the
coast.
• In winter, the water near the coast
will slowly release this energy,
– This will cause coastal areas to be
less cold, in general, than inland
areas in the winter.
Let’s Talk Energy Supply...
• The SUN provides the earth with most of its
energy.
– Warms the Earth
– Used by plants (photosynthesis) to produce
carbohydrates (glucose)
Components of the Earth’s Climate System
• The Atmosphere – Layers of gas
– Ozone in Stratosphere protects from the sun’s
harmful UV rays.
• The Hydrosphere – Water, Water Vapour, Ice
– Absorbs the sun’s energy
– Water Cycle
• The Lithosphere – Earth’s Crust (Land)
– Absorbs the sun’s energy
Atmosphere
• We can only survive in
the Troposphere
• Air in the troposphere
is 78% N2, 21% O2 and
1% other gases
including Ar, CO2, He,
H and O3
The Ozone Layer
• The Ozone (O3) Layer is located between the stratosphere and the
troposphere and helps protect us from UV light from the sun.
• Ozone depletion is caused by human-made compounds called
chlorofluorocarbons (CFC’s)
– Many CFCs have been widely used as refrigerants and
propellants (in aerosol applications). Their manufacture has
been phased out due to their harmful affects.
• High-energy radiation from the Sun enters the atmosphere.
Gases and clouds in the atmosphere trap some of the infrared
radiation from Earth’s surface and radiate it back. This is the
Greenhouse effect.
Infrared (long-wave) Radiation
The Greenhouse Effect
Greenhouse Gases
• Any gas in the atmosphere that absorbs infrared
radiation from the Earth
• Most of the air in the atmosphere is made of N2 and
O2 which do not absorb radiation from the surface of
the Earth
Greenhouse Gases
• Greenhouses gases
include H2O, CO2, CH4,
N2O, CFC’s and a few
others
• They are very low in
concentration
• It is their concentration
in the atmosphere which
determines how much
energy they can absorb
The Greenhouse Effect
The Greenhouse Effect
• The heat from the natural
greenhouse effect warms Earth’s
atmosphere an average of 33°C
• Eventually, this heat dissipates to
outer space
• If there were no greenhouse
effect, Earth’s average
temperature would be -19°C
End of Day 1
Greenhouse Gases
• Consist of less than 1% of the atmosphere
• Produced “naturally” and by human activities
Enhanced Greenhouse Effect
(Human impact on the Greenhouse Effect)
• Humans are increasing the concentrations of
greenhouse gases but by how much???
• What impact do we have?
What is the greenhouse effect?
Water Vapour
(95% of Earth’s greenhouse effect)
• Part of the “natural” greenhouse effect
- Human activities do not release significant amounts
of water vapour into the atmosphere
-remains on average for 9 days
• Most abundant greenhouse gas
• Water vapor constitutes Earth's most
significant greenhouse gas, accounting for about 95% of
Earth's greenhouse effect
The Important Greenhouse Gases (except water vapor)
U.S. Department of Energy
(all concentrations expressed in
parts per billion)
Carbon Dioxide (CO2)
Methane (CH4)
Nitrous Oxide (N2O)
Misc. gases ( CFC's, etc.)
Total
PreTotal
Natural Man-made
Percent of
industrial
Concentration
additions additions
Total
baseline
(ppb)
288,000 68,520
11,880
368,400 99.438%
848
577
320
1,745 0.471%
285
12
15
312 0.084%
25
0
2
27 0.007%
289,158 69,109
12,217
370,484 100.00%
Think about it:
1) What is the most abundant gas?
2) Which gas do you think will have had the
largest % increase (total) post industrial
revolution?
3) Which has had the largest % increase (total)
post industrial revolution?
Nitrous oxide
• Produced when wood and
fossil fuels are burned
• Produced by chemical
industry and released by
bacteria from fertilizers
• Traps heat 296 times
better than carbon dioxide
Carbon Dioxide
• Released when fossil fuels- coal, oil and natural
gas- are burned
• Increases due to the removal and burning of
forests, industrial processes such as the
manufacture of cement, and the cultivation of
soil
The Remaining 5%
• Water vapor accounts for about 95% of Earth's
greenhouse effect
• The remaining 5% is shown below. These charts shows
human influence on the remaining 5% of greenhouse
gases
Anthropogenic (man-made) Contribution to the "Greenhouse
Effect," expressed as % of Total (water vapor INCLUDED)
Based on
concentrations
(ppb)
Water vapor
Carbon Dioxide
(CO2)
Methane (CH4)
Nitrous Oxide
(N2O)
Misc. gases (
CFC's, etc.)
Total
% of
Greenhouse
Effect
% Natural
% Man-made
95.000%
94.999%
0.001%
3.618%
3.502%
0.117%
0.360%
0.294%
0.066%
0.950%
0.903%
0.047%
0.072%
0.025%
0.047%
100.00%
99.72
0.28%
In Summary
•
Water vapor which is responsible
for 95% of Earth's greenhouse effect,
is 99.999% natural. Even if we wanted to
we can do nothing to change this.
•
Anthropogenic (manmade) CO2 contributions cause only
about 0.117% of Earth's greenhouse
effect.
• Adding up all anthropogenic greenhouse
gas sources, the total human
contribution to the greenhouse effect is
around 0.28% .
Global Warming and the
Carbon Cycle
However the general consensus is that an increase in CO2
is directly responsible for Global Warming. Why?
CO2 and Temperature
Where is all the Carbon?
• Inorganic Carbon
– The Atmosphere
– The Ocean
– The Earth’s Crust
• Organic Carbon
– Bodies of Living Things
– Fossil Fuels
Where is all the Carbon?
• Most of the worlds Carbon is held in Carbon Sinks
which is a reservoir, such as an ocean or forest, that
absorbs carbon dioxide from the atmosphere and
stores the carbon in another form (H2CO3)
Human Impact on the Carbon Cycle
Humans affect the carbon cycle by:
• releasing carbon into the atmosphere faster than
would normally occur (burning fossil fuels/wood).
• clearing away vegetation (cutting down forests).
Human Impact on the Carbon Cycle
The Carbon Dioxide Positive Feedback Loop
• Oceans are large Carbon sinks. As temperatures
increase, more ocean water evaporates releasing the
carbon into the atmosphere which further increases
the temperature. This then repeats.
CO2 and Temperature
End of Day 2
Evidence of Climate Change
• Earth’s average temperature has generally
increased from 1880 to 2006.
• What else could account for this increase?
Who Cares???
Effects of Global Warming
The impacts of climate change are
predicted to be serious and
widespread:
• more violent weather
• Increases in global temperatures 
melting glaciers, increase in sea
levels, flooding
• Ecosystems  Creating unsuitable
habitats (melting ice and polar
bears)
• Shifting patterns of rainfall and
drought
1928
South Cascade
Glacier,
Washington
1979
South Cascade
Glacier,
Washington
2003
South Cascade
Glacier,
Washington
A growing body of evidence indicates that humans now have a significant
impact on climate by affecting the carbon cycle.
Why? Look it up.
• An increase in global temperature will create in increase
in disease-carrying organism populations like certain
types of mosquitoes which will lead to increased
disease rates such as West Nile, Malaria, etc.).
Human Health
• “Worldwide increases in the incidences of asthma,
allergies, infectious and cardiovascular diseases will
result from a variety of impacts of global climate
change, including rising temperatures, worsening
ozone levels in urban areas, and expansions of the
ranges of communicable diseases as the planet heats
up”
http://www.ucdmc.ucdavis.edu/publish/news/newsroom/6320
Expected changes - Positive
• An increase in temperature will decrease heating
costs (energy usage) which will decrease CO2
emissions
• Less ice coverage in Great Lakes  longer shipping
seasons
Has abrupt
climate change
happened
before?
YES
Long-Term Cycles in Climate
• Over the last 800,000 years or more, Earth’s climate has
cycled between freezing ice ages and warmer interglacial
periods
• We experience an Ice Age approximately every 100,000
years
Prehistoric Climate Changes
• Climate proxies are
preserved physical
characteristics of the past
that enable scientists to
reconstruct historic climate
conditions
Examples include:
• Pollen records
• Ice core samples
• Marine corals
• Fossils
What can you do? Make a List
• Choose reusable
products
• Use less heat and air
conditioning
• Buy energy-efficient
products
• Drive less
• Turn lights off
• Buy local products
• Plant a tree
• Etc.