4.4 climate change

Essential idea: Concentrations of gases in the atmosphere affect climates
experienced at the Earth’s surface.
4.4 Climate change
Aerial view, meltwater on Greenland ice sheet
http://wired.tw/posts/balog_glacier_photographs

Understandings, Applications and Skills
Statement Guidance
4.4U.1 Carbon dioxide and water vapour are the most significant
greenhouse gases.
4.4 U.2 Other gases including methane and nitrogen oxides have less
impact.
The harmful consequences of ozone
depletion do not need to be discussed and
it should be made clear that ozone
depletion is not the cause of the enhanced
greenhouse effect.
4.4 U.3 The impact of a gas depends on its ability to absorb long wave
radiation as well as on its concentration in the atmosphere.
Carbon dioxide, methane and water vapor
should be included in discussions.
4.4 U.4 The warmed Earth emits longer wavelength radiation (heat).
4.4 U.5 Longer wave radiation is absorbed by greenhouse gases that
retain the heat in the atmosphere.
4.4 U.6 Global temperatures and climate patterns are influenced by
concentrations of greenhouse gases.
4.4 U.7 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.
4.4 U.8 Recent increases in atmospheric carbon dioxide are largely due
to increases in the combustion of fossilized organic matter.
4.4 A.1 Threats to coral reefs from increasing concentrations of
dissolved carbon dioxide.
4.4 A.2 Correlations between global temperatures and carbon dioxide
concentrations on Earth.
4.4 A.3 Evaluating claims that human activities are not causing climate
change.

4.4.U1 Carbon dioxide and water vapour are the most significant greenhouse gases.
4.4.U2 Other gases including methane and nitrogen oxides have less impact. (Page 60)
http://commons.wikimedia.org/wiki/File:GoldenMedows.jpg
The Earth is kept much warmer by gases in the atmosphere that
retain heat. These gases are referred to as greenhouses gases.
The greenhouse gases that have the
largest warming effect on the Earth are:
• carbon dioxide (below)
• water vapor (e.g. clouds)
http://news.bbc.co.uk/2/shared/spl/hi/sci_nat/04/climate_change/html/greenhouse.stm
Other gases including methane
and nitrogen oxides have less
impact.
Greenhouse gases together make up
less than 1% of the atmosphere.
Click Here

• The greenhouse effect is a natural phenomenon that keeps
the surface of the Earth warm due to the presence of an
atmosphere containing these gases that absorb and radiate
heat.
• The greenhouse
effect is the Earth’s
ability to use its
atmosphere to
retain heat and
keep warm even
when no sun is
hitting the surface

The Atmosphere of Earth contains primarily:
N2 (77%) and O2 (21%)
• What happened to all the CO2?
• Where did all the O2 come from?
4.4 U.1 Carbon dioxide and water vapour are the most significant
greenhouse gases.

Where does the CO2 come and go?
Atmospheric CO2 is formed from (The
sources…)
• Volcanic outgassing
• Burning of organic matter (Fossil Fuels)
• Respiration of living organisms
• …
CO2 can be stored in (The Sinks…)
• Highly soluble in water: forms H2CO3
(Carbonic Acid)
• Dissolved CO2 in water can interact with
silicate minerals to form carbonated
minerals…
• …
greenhouse gases.
• CO2 is removed by photosynthesis
and absorption by the oceans

The most important source of O2 on Earth is
Life and Photosynthesis.
• Photosynthesis converts CO2 to O2, and
incorporates carbon into amino acids,
proteins, and other components of living
organisms.
• O2 will be depleted from the atmosphere very
rapidly without a source.
• O2 is a very reactive chemical that likes to be
combined with other elements through
oxidation. For examples, CO2, H2O, FeO (rust)
 That’s how we make fire!
• O2 Absorbs UV, which also transform some of
the O2 into O3(OZONE), which absorbs even
more UV
 O2 not only supports life, it also protect life!
UV light can break the water molecules to release
oxygen, but the contribution is small….
greenhouse gases.

greenhouse gases.
Sources of Water Vapor
• Water is formed by the evaporation
of the oceans, seas and lakes and
transpiration in plants
• It is removed from the atmosphere
by precipitation (rainfall and snow)
• Water continues to retain heat after
it condenses to form droplets of
liquid water in the clouds
• Water reabsorbs heat energy and
radiates it back to Earth’s surface
and also reflects the heat energy
back
• This explains why the temperature
drops so quickly at night in areas
with clear skies than those with
cloud cover

• Earth is undergoing global warming
because of human-generated
greenhouse gases are causing the
atmosphere to retain more and
more heat
• Carbon dioxide, methane, and
oxides of nitrogen are main culprits
Oxides of nitrogen (NOx) :
 released naturally by bacteria
in some habitats and also by
agriculture and vehicle exhaust
Methane (CH4) :
 emitted from marshes, other
water-logged habitats and
from landfill sites containing
organic wastes
4.4 U.2 Other gases including methane and nitrogen oxides have less
impact.
http://extras.mnginteractive.com/live/media/site525/2013
/1103/20131103__EPT-L-LANDFILLS-1104~p2_500.jpg

Greenhouse Gases
• The two factors that determine how much of an influence a gas will
have on the greenhouse effect are
1) The ability of the gas to absorb long-wave radiation (heat)
2) The concentration of the gas in the atmosphere
• The primary components of Earth’s atmosphere, N2 and O2 do not
have absorption in the IR wavelength range, therefore, do not have a
significant role in setting the surface temperature of the planet…
• Greenhouse gas are efficient in absorbing IR light (long wave radiation)
4.4 U.3 The impact of a gas depends on its ability to absorb long wave
radiation as well as on its concentration in the atmosphere. (Page 60)

• Methane causes more warming per molecule than CO2 but it is at a much
less concentration in the atmosphere so its impact on global warming is less.
• Water vapour enters the atmosphere at an immensely rapid rate, but
remains there on average 9 days, where as methane remains in the
atmosphere for 12 yrs, and CO2 even longer.
http://www3.epa.gov/climatechange/ghgemissions/gases.html
(CFC’s)

http://www.sumanasinc.com/webcontent/animations/content/globalcarboncycle.html
The surface of the Earth absorbs short-
wave solar energy and re-emits at longer
wavelengths (as heat).
Approx. 25% of
solar radiation is
absorbed by the
atmosphere.
Approx. 75% of solar
radiation penetrates the
atmosphere and reaches
the Earth’s surface.
Up to 85%* of re-emitted heat is captured
by greenhouse gases in the atmosphere.
*This value, though variable, is known to be
rising; very likely the result of human activities.
Heat passes back to the surface of
the Earth, causing warming
How the greenhouse effect works
1
2
3
4
5
4.4.U4 The warmed Earth emits longer wavelength radiation (heat). (Page 60)
4.4 U.5 Longer wave radiation is absorbed by greenhouse gases that retain the heat in the atmosphere.

The surface of the Earth absorbs short-
wave solar energy and re-emits at longer
wavelengths (as heat).
Approx. 25% of
solar radiation is
absorbed by the
atmosphere.
Approx. 75% of solar
radiation penetrates the
atmosphere and reaches
the Earth’s surface.
Up to 85%* of re-emitted heat is captured
by greenhouse gases in the atmosphere.
*This value, though variable, is known to be
rising; very likely the result of human activities.
Heat passes back to the surface of
the Earth, causing warming
(GLOBAL WARMING)
Remember the Greenhouse Effect is a natural process!!!
1
2
3
4
5
Watch a Greenhouse
animation HHMI

Use the
animations/tutorials
to improve your
understanding and
find out more.
How the greenhouse effect works
http://www.damocles-
eu.org/education/Animation_about_the_greenhouse_effect_182.shtml
http://www.sumanasinc.com/webcontent/animatio
ns/content/greenhouse.html

4.4 U.4 The warmed Earth emits longer wavelength radiation (heat).
Summary:
•When light (shorter wavelengths) enters the Earth’s atmosphere, some
of the light reflects off the Earth’s surface back towards outer space.
•Some of the light is converted into heat, which in turn warms the surface
of the Earth (the air, mountains and water).
•This heat (longer wavelengths) radiates off the Earth back towards the
atmosphere.
•The peak wavelength for
infrared is 10,000 nm,
while the peak wavelength
of solar radiation is 400 nm

4.4 U.5 Longer wave radiation is absorbed by greenhouse gases that
retain the heat in the atmosphere. (Page 60)
• The ability of the Earth’s surface to reflect light is called the albedo effect.
• Light colored and white objects such as snow and ice, have a high
albedo and therefore little light is absorbed and less heat is produced.
Black and dark colored objects like asphalt and pavement have a low
albedo, and therefore absorb more light and produce more heat.
•With the spread
of urban cities
and areas, a
greater amount of
heat is being
produced

Problem: ENHANCED Greenhouse Effect caused
by human activity

• Climate refers to the patterns of temperature and precipitation that occur over
long periods of time.
– Climate changes over thousands or millions of years
• Climatologists and albedo-climatologists collect and study data about
atmospheric conditions in recent decades and from the distant past in order to
infer what the climate was like thousands to millions of years ago
• Since greenhouse gases cause the earth to retain heat, one can infer that the
more greenhouse gas there is in the atmosphere, the warmer the earth will be.
• This does not mean that the amount of greenhouse gas is the only reason for
the Earth warming and cooling; however, there is a correlation between the
Earth’s temperature and the amount of greenhouse gas
– Other factors such as the cycles in the Earth’s orbit around the sun,
variations in the amount of solar radiation due to sunspot activity, past
volcanic activity, and changes or oscillations in ocean currents
• Even if greenhouse gases aren’t the only factor in the rise of the Earth’s
temperature, if the Earth heats up even a few degrees, it will have profound
effects on the climate patterns
4.4 U.6 Global temperatures and climate patterns are influenced by
concentrations of greenhouse gases. (Page 60)

• Climate effects of higher greenhouse gas concentrations include:
higher global average temperatures
more frequent and intense heat waves
some areas becoming more prone to droughts
some areas more prone to intense periods of rainfall and flooding
tropical storms to be more frequent and more powerful
Changes to ocean currents, e.g. weakening of the Gulf Stream would
mean colder temperatures in north-west Europe
http://tcktcktck.org/2013/07/flooding-in-india-highlights-need-for-climate-ready-development/

4.4.U7 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. (Page 60)
4.4.U8 Recent increases in atmospheric carbon dioxide are largely due to increases in the
combustion of fossilized organic matter. (Page 61)
Key points
• Global temperatures
show large variations
(for various reasons)
• (despite this) there is
strong support for
correlation between
atmospheric carbon
dioxide and global
temperatures
Watch Video

• Since the industrial revolution the amount of CO2 has
drastically increased, largely due to the increasing
quantities of combustion of fossilized organic matter
(coal, oil and natural gas)
• The number one source of carbon emissions due to
human activities is through combustion of fossil
fuels in automobiles, buses and planes.
• Another source of carbon dioxide is the
deforestation through burning large tracks of land
and heating homes with fossil fuels, such as natural
gas
• Humans demand for meat has led to large numbers
of cattle, which is responsible for releasing
methane into the atmosphere, which is changed
into carbon dioxide
• As the human population increases and countries
become more industrialized, human production of
greenhouse gas, shows no sign of slowing down

http://radioviceonline.com/wp-content/uploads/2009/11/knorr2009_co2_sequestration.pdf
Industrial revolution
has started
Large increases in
usage of fossil fuels
The link between human emissions and atmospheric levels of CO2
Key points
• There is a strong correlation
between human emissions
and atmospheric levels of CO2
• As atmospheric CO2 levels
have increased the amount of
CO2 absorbed by carbon sinks
has increased (only about
40% of emissions have
remained in the atmosphere)

• As evident from the graph on the left, there has been large fluctuations of
temperature and carbon dioxide concentration over the past 400,000 years
• The concentrations of CO2 varied between about 300 ppm during warmer
interglacial periods and about 170 ppm during glacial cooling periods
• However, over the past 200 years the amount of CO2 has risen to unprecedented
highs of about 380-390 ppm as seen in the graph on the right
Evidence for a correlation between atmospheric carbon dioxide (CO2) and
average global temperatures
4.4 A.2 Correlations between global temperatures and carbon dioxide concentrations
on Earth. (Page 61)

The Long-Term Stability of Earth’s Climate−400,000 years
• The atmospheric concentration
of CO2 measured from Antarctic
ice core data implies that Earth’s
climate has being pretty stable
over the past 400,000 years
• It also shows a rapid increase of
about 30% in the past few
centuries…
– 280 ppm (parts per million)
to 380 ppm
CO2 concentration and global
temp are correlated but not
directly proportional as other
variable factors affect
temperature.
Fluctuations in temperature (blue) and in the atmospheric
concentration of carbon dioxide (red) over the past 400,000 years
as inferred from Antarctic ice-core records. The vertical red bar is
the increase in atmospheric carbon dioxide levels over the past
two centuries and before 2006.
From A. V. Fedorov et al. Science 312, 1485 (2006)17. 18.
Reproduced from EPA Climate Change Website.
4.4 A.2 Correlations between global temperatures and carbon dioxide
concentrations on Earth.

• To deduce historic carbon
dioxide concentrations and
temperatures ice cores are
drilled in Antarctic ice sheets
• A cylinder of ice was
collected by drilling from to
the bottom of the Antarctic
ice sheet. The total length of
the core was 2083 meters.
• The core shows annual
layers, which can be used to
date the air bubbles trapped
in the ice.
• Analysis of the gas content of
the bubbles gives both the
concentration of carbon
dioxide in the atmosphere
and the air temperature
(from oxygen isotopes) at the
time ice was formed.
Sample ice core
Watch videos to
find out more
about the ice cores

Not everybody is convinced of the
greenhouse gases - global warming
theory
• At this point, it appears that the
warming itself is real – the surface
temperature indeed becomes higher
in the last few decades.
• The question is – Is the warming
caused by the greenhouse gases
(especially CO2)?
• Some groups, especially the IPCC
members argue strongly for it. But
there are other groups that are not
convinced. The summary to the right
is from Robinson et al. (1998).
Summary
World leaders gathered in Kyoto, Japan, in December 1997
to consider a world treaty restricting emissions of
''greenhouse gases,'' chiefly carbon dioxide (CO2), that
are thought to cause ''global warming'' severe increases
in Earth's atmospheric and surface temperatures, with
disastrous environmental consequences. Predictions of
global warming are based on computer climate
modeling, a branch of science still in its infancy. The
empirical evidence actual measurements of Earth's
temperature shows no man-made warming trend.
Indeed, over the past two decades, when CO2 levels
have been at their highest, global average temperatures
have actually cooled slightly.
You can get this from the following website
http://www.oism.org/pproject/review.pdf
You can get IPCC reports at http://www.ipcc.ch/
change. (Page 61)

4.4.A3 Evaluating claims that human activities are not causing climate change.
http://www.skepticalscience.com/
Many claims that human activities are
not causing climate change have been
made in the media, whether it be in
newspapers, on television or on the
internet.
It is important to realize that not all
sources are trustworthy and it is
important to know the motivation of
those publishing claims on either side of
the debate.
Video: The Truth About Global
Warming - Science & Distortion
- Stephen Schneider

Some examples of criticisms
• There are evidence showing that
the current temperature isn’t really
that warm compared to what was
two to three thousand years ago.
The figure to the right shows that
the temperature of Sagaso Sea
fluctuates in a range of ~ 3.6°C.
• Also the “trend” depends on the
data sets and the section of data
you select to examine – see the
lower chart. By using a different
data set (here the satellite
microwave sounding) and selecting
a suitable section (for example,
1978-1998) you can actually show
that there was a cooling, not
warming.
change.

There are also evidence showing that the solar activity seems to have some
influence on atmospheric temperature. But there are many questions here.
Especially on how and how much.
change.

Global Warming: More than a scientific problem - Aside from scientific problems,
there are political problems as well.
At Climate Meeting, Unlikely Ally for Have-Nots
By AMY WALDMAN
New York Times 1 Nov 2002
NEW DELHI, Friday, Nov. 1 — When India's
prime minister, Atal Bihari Vajpayee,
finished speaking at the international
conference on climate here on
Wednesday, the fissure between richer
and poorer countries over how best to
tackle global warming could no longer be
papered over.
In his speech, he argued that poorer
countries could not be expected to invest
money in tackling the causes of global
warming. They bear little responsibility, he
said, producing fewer greenhouse gases
than industrialized countries, and yet have
been hit harder by the natural calamities,
from drought to floods, caused by climate
changes. They have weaker economies,
and with pressing needs in everything
from health to education, can little afford
to invest in clean-air technologies.
His speech articulated sentiments —
resentments, in some cases — widely shared
among developing nations. So while it produced
little new of substance, the conference, the
eighth since the United Nations Framework
Convention on Climate Change was adopted in
1992, illuminated the challenges in crafting a
global response to global warming.
It highlighted a divide between north and south,
between the industrialized and developing
worlds, over who should bear the obligations and
burdens of trying to reduce the emissions that
cause global warming.
But on several points, the south found itself with
an unlikely ally: the United States, which under
the Bush administration has also blanched at
joining efforts to reduce emissions.
Instead, the United States joined India and other
developing countries in encouraging a focus on
developing the technology and finding the
resources to adapt to climate change.

What is ocean acidification?
•Ocean acidification is the ongoing decrease in the pH of the
Earth's oceans, caused by the uptake of carbon dioxide from the
Earth’s atmosphere.
•pH of surface layers of the earth’s oceans in the late 18th century ≈ 8.1179
currently ≈ 8.069, which represents about a 30% acidification.
4.4 A.1 Threats to coral reefs from increasing concentrations of dissolved carbon
dioxide. (Page 61)
• Over 500 billion
tones of
CO2 released by
humans since
the start of the
industrial
revolution have
been dissolved in
the oceans
The burning of fossil fuels releases
11 BILLION TONS
of carbon dioxide into the atmosphere
every year

• Reef-building corals that use calcium carbonate in their exoskeletons need to
absorb carbonate ions from seawater.
• The concentration of carbonate ions is low in seawater because they are not very
soluble.
• Dissolved CO2 makes the carbonate concentration even lower as a result of some
interrelated chemical reactions
• If the carbonate ions concentrations drop it is more difficult for reef-building corals
to absorb these ions to make their exoskeletons
•Also, if seawater ceases to be a saturated solution of carbonate ions, existing
calcium carbonate tends to dissolve, so existing exoskeletons of reef-building corals
are threatened.

Ocean acidification: Impacts on individual
marine organisms
Thinner, smaller and weaker shells in shellfish
• Especially larval stages, which already have thin
shells
•Fitness effect: Lower survival due to
 increased crushing and drilling by
predators,
 increased risk of desiccation during low
tide Normal
Acidic
Really
acidic
dioxide.

Ocean acidification: Impacts on individual marine organisms
Reduced fertilization of gametes in corals and other marine organisms
• Deformed flagellum in sperm that impacts their swimming
• Fitness effect: lower population growth
Natural range in the ocean
dioxide.

• Volcanic vents in the Gulf of Naples have been releasing carbon dioxide
into the water for thousands of years, reducing the pH of the seawater.
• In this area of acidified water there are no corals, sea urchins or other
animals that make their exoskeletons from calcium carbonate.
• In their place other organisms like invasive algae and sea grasses flourish.
• Unfortunately this could be the disheartening future for coral reefs around
the world if carbon dioxide emissions continue to rise.

4.4.A1 Threats to coral reefs from increasing concentrations of dissolved carbon dioxide.
Ocean acidification – the causes and effects
http://www.sumanasinc.com/webcontent/animations/content/acidific
ation.html
Research indicates that, by 2100 coral reefs
may erode faster than they can be rebuilt. This
could compromise the viability of these
ecosystems and the (estimated) one million
species that depend on coral reef habitat.
http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F
http://youtu.be/5cqCvcX7buo
http://youtu.be/GL7qJYKzcsk
http://youtu.be/Wo-bHt1bOsw
Watch videos to
find out more
about ocean
acidification

Bibliography / Acknowledgments

4.4 climate change

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