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Bell Ringer
Glasgow is the largest city in Scotland. Glasgow
sits at 58⁰N latitude, is about 39 meters above
sea level, and is very close to the Atlantic
Ocean. In addition, this city is supplied by a
warm water current (the Gulf Stream).
1. Using this information, predict Glasgow’s
climate, in terms of temperature and
precipitation.
2. While Glasgow sits in the temperate zone,
would you expect to see strong seasonal
variance? Why or why not?
What is the ozone layer, and why is it important?
OUR OZONE SHIELD
Our Ozone Shield
 The ozone layer is found within the
stratosphere. Ozone molecules (O3) are found
in very high concentrations here.
 Ozone is vital because it absorbs a significant
percentage of incoming ultraviolet (UV)
radiation.
 Why do we want to block UV radiation?
Our Ozone Shield
Our Ozone Shield
 Note from the diagram that UV radiation can
be divided into UV-A, UV-B and UV-C
radiation wavelengths.
 The ozone layer effectively blocks UV-B and,
while it is not shown, UV-C. These are the
most harmful wavelengths by far.
 UV-A has a longer wavelength, so it can
bypass the ozone layer. However, it is also the
least harmful UV radiation.
Our Ozone Shield
Organism
How is it harmed through UV radiation?
Humans
Skin cancer, premature aging, increased risk of
cataracts, weakened immune system
Amphibians
Reduced chance of egg survival, increased risk of
genetic mutations, increased vulnerability to other
stresses and limiting factors
Marine Life
Death of phytoplankton (producers!), disruption of
the local food networks
Land Plants
Interference with normal photosynthesis, reduced
crop yields
The Ozone Hole
 Throughout the spring, the ozone layer thins
out above the South Pole (Antarctica). This
causes an ozone hole to appear.
 This was first officially discovered in 1985.
 While ozone levels vary throughout the year,
a trend toward gradual thinning of the ozone
layer was discovered as far back as 1979. Over
time, ozone levels over the Artic (North Pole)
have also dropped.
 Why?
The Ozone Hole
 Primarily, this was caused through the
influence of chlorofluorocarbons (CFCs), a
class of compounds once used as coolant, in
aerosols, and as a foam additive.
 They’re attractive because they are cheap,
nontoxic, nonflammable, and noncorrosive.
The Ozone Hole
 Close to the Earth’s surface, CFCs are quite
inert and harmless.
 However, CFCs that ascend to the
stratosphere react with abundant UV
radiation to form reactive molecules. This
occurs in polar stratospheric clouds, high
altitude clouds made of water and nitric acid.
 These molecules can react with ozone in the
ozone layer, depleting the ozone!
Defending Our Ozone
 In 1987, the Montreal Protocol was first
ratified in Canada. This was an agreement to
limit the production of future CFCs.
 Since its inception, it has been ratified by
most of the world’s countries.
 As a result, in 2012 the ozone hole reached its
smallest reported size in the past decade!
Defending Our Ozone
 Though the Montreal
Protocol has been
quite successful,
scientists continue to
monitor the ozone
layer, as CFCs will still
be present for many
years to come.
Bell Ringer
 This graph shows monthly rainfall for Hawaii for the
years 2004-2008 (in inches)
Year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Ann.
2004
6.88
9.47
0.56
0.58
1.29
0.31
0.09
3.74
1.01
1.25
7.97
5.96
39.01
2005
6.23
1.28
1.88
0.64
0.27
0.28
0.28
0.10
0.90
1.60
2.50
0.58
15.60
2006
1.53
2.62
16.92
0.75
1.11
0.09
0.08
0.11
0.66
2.50
2.50
0.58
29.45
2007
1.10
0.40 0.68
0.20
0.12
0.16
0.05
0.09
0.50
0.15
5.46
3.08
11.99
 Examine the graph and answer the questions:
1. Was 2007 an El Nino or La Nina year?
2. How do you know this?
How are we affecting both local and global climates?
CLIMATE CHANGE
The Greenhouse Effect
 Greenhouse gases – gases that can absorb
and radiate radiation from the sun – are
needed to moderate Earth’s temperature.
Without them, the Earth’s climates would be
too extreme to support life as we know it.
 Carbon dioxide, methane, nitrous dioxide and
water vapor are the primary greenhouse gases.
 This is known as the greenhouse effect.
The Greenhouse Effect
 However, excessive amounts of greenhouse
gases will trap an excessive level of thermal
energy in the atmosphere.
 The excess thermal energy can lead to
changes in weather and climate patterns all
over the world.
 This is especially critical as it pertains to
carbon dioxide; CO2 levels have risen
dramatically in the past 50 years.
Climate Change
 Both global warming and global cooling
define changing trends in the Earth’s climate.
 Scientists used to refer to the trend in
increasing thermal energy as global warming.
However, this is not an accurate picture of all
of the effects of this phenomenon.
 We now define this trend as climate change,
since there are effects well beyond rising
temperatures on Earth.
Climate Change
 What could the localized effects of global
climate change be?
 Rising sea levels – trapped thermal energy warms
the oceans, and melts terrestrial ice shelves. This
could cause widespread flooding and salination of
freshwater reservoirs.
 Changing weather patterns – excess thermal
energy can alter both wind and ocean currents,
changing local climates.
Climate Change
 What could the localized effects of global
climate change be?
 Mass extinction – climate change would change
local ecosystems, prompting mass migrations and
extinctions, and changing local food networks.
 Health concerns – deaths due to adverse weather
are a concern, as are an increase in disease vectors
(e.g., mosquitoes or bats).
 Agriculture – changing climates could disrupt local
agriculture and stress local irrigation systems.