Climate Change
The Atmosphere: Earths big blanket
4.4 Understandings:

Carbon dioxide and water vapour are the most significant greenhouse gases.

Other gases including methane and nitrogen oxides have less impact.

The impact of a gas depends on its ability to absorb long wave radiation as well as on its
concentration in the atmosphere.

The warmed Earth emits longer wavelength radiation (heat).

Longer wave radiation is absorbed by greenhouse gases that retain the heat in the atmosphere.

Global temperatures and climate patterns are influenced by concentrations of greenhouse gases.

There is a correlation between rising atmospheric concentrations of carbon dioxide since the
start of the industrial revolution 200 years ago and average global temperatures.

Recent increases in atmospheric carbon dioxide are largely due to increases in the combustion of
fossilized organic matter.
Topic 4.4 – Climate Change
Applications and Skills
 Application:
Threats to coral reefs from increasing
concentrations of dissolved carbon dioxide.
 Application:
Correlations between global
temperatures and carbon dioxide concentrations on
Earth.
 Application:
Evaluating claims that human activities
are not causing climate change.
Sunlight = short and infrared = long
The atmosphere: Earths big blanket
?
The atmosphere: Earths big blanket
-Vital in regulating temperature:
Though temperatures vary between -80◦C to +50 ◦C, mean temp
is around 14◦C and remains relatively constant in most places from day
to night.
In contrast, the moon, which is about the same distance from
the sun has temperatures that fluctuate from -150 ◦C to +120 ◦C
It is estimated that without the atmosphere earth would be 32◦C
colder or -18 ◦C
How does the earth regulate itself?
Using a “greenhouse” to illustrate the greenhouse effect
• Sunlight passes through glass
• Sunlight is made of short
wavelengths, which are not
warm
• It’s only when sunlight hits
objects (plants, soils etc) and its
energy is transformed into heat
(long wavelength infrared = IR)
• Now the heat (IR) that has been
absorbed by the objects in the
greenhouse is radiated out and
shared
• The hear as IR stays in the
greenhouse because the glass is
not as transparent to IR heat as it is
to sunlight
• Reason temperature can be higher
than the outside
• The glass is acting like an
atmosphere
CHG’s act in a similar manner to the glass
(natural!)
• C02 and H20 vapour have the
ability to absorb and radiate IR
• These act to help maintain the
earth surface temperature by
radiating the heat back down
• NOx and CH4 as well but to less
extent
Different gas different impact CO2, NOx and
CH4?
• Different gases have a different
impact on the greenhouse effect
• Ability of the gas to absorb the
longwave radiation IR
• Concentration of the gas in the
atmosphere
Different gas different impact CO2, NOx and
CH4?
• CH4 has more potential to warm
the planet than CO2 but only lasts
12 years versus C02, 50 50 200
years.
• Since 1750
• C02 concentration has increased by
40%
• CH4 has increased by greater than
150%
• However, atmosphere today:
• CH4 concentration is 1700ppb
• C02 concentration is 400 ppm
• C02 is 200 time greater!
Different gas different impact CO2, NOx and
CH4?
• Same story for NOx
• Although N0x has more than 100
times the global warming power
than C02 its concentration is only:
• 320ppb a fifth of CH4
• 1000 times less that of C02
• Concern yes, but not the priority
Albedo: ability of a surface to reflect light
So how do GHG’s help warm the earth?
• Ask if there was no atmosphere (glass) what would happen?
• Earth would have no way to retain heat
• The GHG’s absorb and re-radiate the IR from low albedo object on earths
surface
-Some heat (IR) passes though the atmosphere. Reason it cools
at
night but when the sun rises it begins to warm again
- also the reason why it feels warmest at 4 when the sun is not at
its strongest, the low albedo objects have been absorbing and
radiating all day
Winter?
And if we alter the blanket?
Global climate change is being affected by
GHG emissions
• Climate refers to the temperature and precipitation patterns over
time. Change in these patterns is natural over extended periods of
time
• Climatologists and paleoclimatologists study climate patters
Use of proxies to understand past climate conditions,
NOS 207
Proxy data show
• 15000 years ago we were in an
ice age
• 10000 years ago it came to an
end and we are now in an
interglacial period
• Last ice age was the result of a 5
degree drop in temperature
What causes natural temperature fluctuation?
What causes natural temperature fluctuation?
Volcanic activity and particles in the atmosphere
Quantity of radiation from the sun
Position of the continents
Oscillations in ocean currents
Positive C02 Feedback loop
• As oceans warm up they are less able to absorb C02
Increase in temp  ocean can absorb less  increased C02 in the
atmosphere  increased temp  less ability to absorb  increase C02
The industrial revolution and GHG’s
• Since the 1800’s C02 emissions
have been on the rise, increase
of 35% in atmosphere
• Mainly result of:
• fossil fuel based travel
• Planes, trains, automobiles
• Product manufacturing and
transport
• Diet high in meat
N0x in the atmosphere
• Using organic and commercial
fertilizers in agrictulure
• Burning coal to produce
electricity
• Cars
• Manufacturing products
Threats to coral reef
• How is a reef formed?
Very sensitive to
• pH
• temperature
• depth
Is it us? Are we sure? Are you sure?
Arguments:
Words to live by:
• The Precautionary Principle
• The precautionary principle denotes a duty to prevent harm or
damage, when it is within our power to do so, even when all the
evidence is not in.