There is a two-way relationship between climate change and environmental change. Climate change can drive environmental changes through factors like changes in temperature and precipitation. However, environmental changes like pollution can also trigger further climate change. The chapter discusses both natural and human causes of climate change such as variations in Earth's orbit, volcanic eruptions, and increased greenhouse gas emissions from human activities. It also describes how climate change impacts the atmosphere by increasing global surface temperatures and temperature variations around the world.

1. Chapter 3: The Relationship between Climate
Change and Environmental Change
3.1 Overview
• The earth has entered a period of hydrological,
climatological, and biological changes that differ from
previous episodes of global change in the extent to
which it is human in origin.
• To explain or predict the course of the present global
environmental changes, one must therefore understand
the human sources, consequences, and responses,
some of which can alter the course of global change.

2. • There is two-way relationship between climate
change and environmental change
• On one hand, the major driving causal factor for
local, national, regional, and global environmental
changes is climate change.
• On the other hand, after the environment has been
changed either by natural or by human-induced
factors, it triggers climate change again.

3. 3.2 Climate Change
• Climate change refers to a long-term change in the
average weather pattern over a specific region in a
significant period of time.
• It is also seen as a change in the statistical distribution
of weather patterns when that change lasts for an
extended period of time (i.e. decades to millions of
years).
• The most general definition of climate change
is a change in the statistical properties of the climate
system when considered over long period of time.
• As such, fluctuations over periods shorter than few
decades, such as El Nino do not represent climate
change. They may be described as climate variability.

4. • The term sometimes is used to refer to climate
change caused by human activity as opposed to
change in climate that may have resulted as part of
Earth’s natural processes.
• In this sense, especially in the context of
environmental policy, the term climate change has
become synonymous with ‘’anthropogenic global
warming’’.
• Some scientific journals are of the opinion that
“global warming refers to surface temperature
increases while climate change includes global
warming and everything else that increasing
greenhouse gas levels will affect.’’

5. • Climate change is also seen as a change in global or
regional climate patterns, in particular, a change
apparently from the mid to late 20th century onwards
and attributed largely to the increased level of
atmospheric carbon dioxide (CO2).
• Environmental changes have to do with changes
caused by the variation in the occurrences of some
climatic factors; rainfall, temperature, humidity, air
pressure and wind: biotic factors; predators, parasites,
soil micro-organism, pest and diseases: edaphic
factors; soil pH, soil texture, soil structure etc. when
environmental changes occur as a result of the actions
of man and other natural phenomena, lives and
properties are adversely affected.

6. 3.2.1 Causes of Climate and Environmental Changes
• In a broad sense, climate and environmental changes are
the aftermath of so many human activities and some
natural occurrences.
3.2.1. 1. Natural Causes of Climate and Environmental
Changes
• Some natural causes of climate change are referred to as
‘’climate forcing’’ or ‘’forcing mechanisms’’.
• Changes in the state of this system can occur externally
(from extraterrestrial systems) or internally (from ocean,
atmosphere and land systems), through any one of the
described components.
• For example, an external change may involve a variation
in the Sun’s output which would externally vary the
amount of solar radiation received by the Earth’s
atmosphere and surface.

7. • Internal variations in the Earth’s climate system may
be caused by changes in the concentrations of
atmospheric gases, mountain building, volcanic
activity, and changes in the surface or atmospheric
albedo.
• However, some climatologists are of the opinion that
only a limited number of factors are primarily
responsible for most of the past episodes of climate
change on the Earth.

8. These factors include;
 Variations in the Earth’s orbital characteristics
 Atmospheric carbon dioxide variations
 Volcanic eruptions
 Variation in solar output
 Plate Tectonics
 Thermohaline Circulation
a. Variation in the Earth’s orbital characteristics
• The Milankovitch theory opines that normal cyclical
variations in three of the Earth’s orbital characteristics is
likely responsible for the past climatic change.
• By implication the theory assumes that over time these
three cyclic events vary the amount of solar radiation
that is received on the Earth’s surface.

9. • The first cyclical variation is known as eccentricity.
• This controls the shape of the Earth’s orbit around the
Sun.
• The Earth’s orbit in a very gradual manner changes from
being elliptical to be almost circular and then back to
elliptical in a period of about 100,000 years.
• As the eccentricity of the orbit increases, the variation in
solar energy received at the top of the atmosphere
between the Earth’s closest (perihelion) and farthest
(aphelion) approach to the Sun increases as well.
• Currently, the Earth is passing a period of low eccentricity.
• The difference in the Earth’s distance from the Sun
between perihelion and aphelion (which is only about 3%)

10. • The further away from the Sun a planet is, the slower
the planet's orbital speed and the longer its path.
• Both of those factors result in taking longer to make
one complete orbit and a planet having a longer year.
• Changes in the Earth's orbit around the sun
and changes in the tilt and wobble of the Earth's
axis can lead to cooling or warming of the Earth's
climate because they change the amount of energy
our planet receives from the sun.
• Eccentricity strongly moderates the effect of conical
sweep of axis of rotation. Indeed, for a circular orbit,
there is simply no perihelion or aphelion, and the
larger the eccentricity, the stronger the differences
between a “mild winter” at perihelion, and a “cold
winter” at aphelion.

11. • When are Aphelion and Perihelion? Aphelion always
happens in early July and Perihelion always
happens in early January.
• About two weeks after the June solstice, Earth is
farthest from the Sun.

13. b. Volcanic Eruption
• During volcanism, materials from the earth’s core and
mantle are brought to the surface as a result of the heat
and pressure generated within.
• Volcanic eruptions and geysers release particles into the
earth’s atmosphere which affect the climate.
• The most dangerous of these gases is the carbon dioxide gas
which reacts with water vapour commonly found in the
stratosphere to form a dense optically bright haze layer that
reduces the atmosphere transmission of some of the sun’s
incoming reception.
• Climatologists for a long time have noticed that there is a
link between very explosive volcanic eruptions and short
term climate change.
• For instance, a year after the Tambora volcanic eruption in
1815, there came very cold years.
• As such there has been very cold weather in regions across
the planet.

14. c. Solar output variations
• There are many variations in solar activity that have
been observed through the sun and beryllium
isotopes.
• The sun provides the earth with heat energy, an
integral part of our climate.
• Numerical climate models predict that if there is a
change in solar output of only 1% per century, the
earth’s average temperature will be altered by
between 0.5 to 1.0 degree Celsius.
• In fact, solar radiation has caused a phenomenon
known as global warming.

15. d. Plate Tectonics
• Planet Earth has a landmass made up of plate
tectonics that shift, rub against one another and
even drift apart.
• This causes the repositioning of continents, wear and
tear of mountains, large–scale carbon storage and
increased glaciations.
e. Thermohaline Circulation
• The relationship between the atmosphere and the
ocean equally results in climate changes.
• Thermohaline circulation is the redistribution of heat
via slow and deep oceanic currents.

16. 3.2.1.2 Human-induced Causes of Climate and
Environmental Change
• The most threatening climate and environmental changes
occur as a result of human activities.
• This is because our planet is unique to support life.
• However, within the limitations of our understanding of
the terms evolution and progress, human beings
contributed to a number of disastrous climate change
triggers.
• Some of them are increase in greenhouse gas levels (e.g.
CO2, N2O, CH₄) and increase in land, water and air
pollution levels.
• Therefore, the high level of industrial pollution and a
number of human induced processes have resulted in
climate change and environmental hazards.

17. • Pollution is the process by which substances are added
to the environment or the addition of materials to the
environment that damages or defiles it, making it
undesirable for life.
• These materials are called pollutants.
• Human populations increase and as society becomes
more industrialized and urbanized, the problem of
pollution has become more serious.
• Obviously many of the products of modern technology
which find their ways into the air and water are toxic
and harmful to life of organisms and the entire
ecosystem.
• Below are outlines of environmental pollutants caused
by human activities.

18. a. Air pollutants
• Air pollution occurs as a result of incomplete burning of
fuels such as coal, oil, petrol and wood.
• Apart from human activities, the gaseous pollutants
emitted into the air can also be by natural occurrences
such as biological decay, forest fires or volcanic eruptions
as mentioned earlier.
• These harmful gaseous pollutants include sulfur dioxide,
nitrogen oxides, carbon dioxide, carbon monoxide and
lead.
b. Water pollutants
• Rivers, streams and lakes are polluted by waste materials
dumped into them by humans.
• These affect communities that live in such areas.

19. • The following are the various ways water can be
polluted;
i. Sewage- when untreated sewage is discharged into
rivers and lakes, they cause the breathing of
bacteria.
• Bacteria grow and multiply using the oxygen in the
water, thereby causing fish and other
organisms in the water to die.
• These bacteria can also continue to break down the
organic wastes, thereby releasing foul-smelling gases
like hydrogen sulfide and ammonia.
• Untreated sewage also causes diseases like cholera
and typhoid which sometimes get into wells, bore-
wholes and sources of drinking water, which may
result in epidemics.

20. ii. Fertilizers- these are chemicals used by farmers to
increase yields of crops.
• The fertilizers contain nitrates and phosphates which
are useful nutrients for the growth of algae and
plants.
• However, the over use of chemical fertilizers may
cause water pollution in the sense that fertilizers that
are not absorbed by crops may be washed away by
rainwater into nearby rivers and lakes. These are
harmful to water organisms.

21. iii. Inorganic wastes- these include industrial wastes
such as poisonous metals like mercury, arsenic and
cadmium.
• These can be disposed of into rivers, streams and
lakes.
• This can be illustrated by what happened in
Minamata, a coastal town in Japan in 1972.
• A plastic factory had discharged waste water
containing high concentration of mercury.
• About 40 people who eat the contaminated fish and
shellfish died of mercury poisoning.
• About 70 people were crippled; blinded or paralyzed.

22. iv. Pesticides – these are substances used to kill pests
that destroy crops in farms.
• They include insecticides and herbicides.
• Insecticides are specifically used to kill insects.
• When applied to farms, they can be carried by rain
water into rivers, streams and lakes.
• When they are in high concentration they may poison
fish or animals that drink the water or feed on the
contaminated fish.
• Again, insecticides DDT (Dichloro-
diphenyltrichloroethane) are insoluble, and as such
are stored in the fatty tissues of animals that
consume them, and as such may result in serious
health hazards.

23. • Also herbicides are substances used to kill weeds.
• Agriculturalists are of the view that herbicides like
‘’2, 4, 5-T, contain an impurity called dioxin, which is
harmful to human beings.
c. Noise pollution
• This is a type of pollution whereby excessively loud
and unpleasant sounds of more than 80 decibels are
produced.
• The world, especially African nations have become
very noisy.
• There are heavy machineries, construction sites,
mining activities that produce noise.

24. • Electrical gargets that produce noisy sounds like
microphones, radios, megaphones, TVs, etc. are
indiscriminately used in homes, cities, market places,
streets, churches, mosques, hotels, club houses, etc.
• Drivers of cars and Lorries blow horns of their
vehicles at random.
• All these cause noise pollution which causes harm to
humans.
• Prolonged exposure to noise can result in severe loss
of hearing.
• Noise pollution in any environment can also cause
emotional stress, irritability, lack of sleep or
insomnia, high blood pressure, psychological
disturbances and low work productivity.

25. d. Soil pollution
• These are the buildup of chemical substances and other
waste materials from factories in the soil.
• The presence of these substances makes the soil to lose its
fertility and lead to the leaching of nutrients into water,
and death of plants, crops or even animals.
• Other causes of soil pollution include;
 Inorganic nutrients like nitrates and phosphorous
from the use of fertilizers
Toxic chemicals from the indiscriminate use of
pesticides
 Oil spill from oil pipes
 Heavy metals such as chromium, cadmium and
copper from smelting industries
 Liquid sewage wastes
 Solid wastes such as rubbish, domestic refuse,
paper, plastic and glass
 Deforestation

26. 3.3 The atmosphere and climate change
• Atmosphere, mixture of gases surrounding any celestial
object that has a gravitational field strong enough to
prevent the gases from escaping; especially the
gaseous envelope of Earth.
• The principal constituents of the atmosphere of Earth
are nitrogen (78%) and oxygen (21%).
• The atmospheric gases in the remaining 1% are argon
(0.9%), carbon dioxide (0.03%), varying amounts of
water vapor, and trace amounts of hydrogen, ozone,
methane, carbon monoxide, helium, neon, krypton,
and xenon.
• The layers of the atmosphere are the troposphere, the
stratosphere, the mesosphere, the thermosphere, and
the exosphere.

27. • The troposphere is the layer in which weather occurs
and extends from the surface to about 16 km above sea
level at the equator.
• Above the troposphere is the stratosphere, which has an
upper boundary of about 50 km above sea level.
• The layer from 50 to 90 km is called the mesosphere. At
an altitude of about 90 km, temperatures begin to rise.
• The layer that begins at this altitude is called the
thermosphere because of the high temperatures that
can be reached in this layer (about 1200°C).
• The region beyond the thermosphere is called the
exosphere.
• The thermosphere and the exosphere overlap with
another region of the atmosphere known as the
ionosphere, a layer or layers of ionized air extending
from almost 60 km above Earth’s surface to altitudes of
1,000 km and more.

28. • Climate change is obviously linked to the atmosphere
since the climate can be defined as the average
conditions of the atmosphere.
• In the current period of climate change, the most
obvious effect is that global surface temperatures are
increasing.
• This can be shown through the ‘temperature anomaly’
which means the difference between the average
temperature in a given year and the long term average
temperature.
• A positive value (i.e. above 0 degree) indicates that the
year was warmer than average.
• The temperature anomaly has been increasing,
indicating that the atmosphere is now almost 1 degree
warmer than it has been over the long term average.

29. • However, this temperature variation is not
experienced everywhere at the same rate.
• Some places warm up faster than others, and other
places can experience reductions in overall
temperature.
• The temperature is rising throughout the 20th
century and beyond, but that some areas such as
parts of the Southern Ocean (around Antarctica)
become somewhat cooler.

30. The Impact of Ozone Depletion on Global Environmental
Change
What is ozone and where is it in the atmosphere?
• Ozone is a gas that is naturally present in our
atmosphere.
• The word ozone is derived from the Greek word
oζειν (ozein),, meaning to smell.
• Ozone has a pungent odor that allows it to be detected
even at very low amounts.
• Ozone has the chemical formula O3 because an ozone
molecule contains three oxygen atoms .
• Ozone was discovered in laboratory experiments in the
mid- 1800s.
• Ozone’s presence in the atmosphere was later discovered
using chemical and optical measurement methods.
• Ozone reacts rapidly with many chemical compounds and
is explosive in concentrated amounts.

31. • Electrical discharges are generally used to produce
ozone for industrial processes such as air and water
purification and bleaching of textiles and food products.
Location of Ozone
• Most ozone (about 90%) is found in the stratosphere,
which begins about 10.16 kilometers above Earth's
surface and extends up to about 50 kilometers altitude.
• The stratospheric region with the highest ozone
concentration is commonly known as the ozone layer.
• The ozone layer extends over the entire globe with
some variation in altitude and thickness.
• The remaining ozone, about 10%, is found in the
troposphere, which is the lowest region of the
atmosphere, between Earth's surface and the
stratosphere.

32. Ozone Concentration
Ozone molecules have a low relative concentration
in the atmosphere.
In the stratosphere near the peak concentration of
the ozone layer, there are typically a few thousand
ozone molecules for every billion air molecules.
Most air molecules are either oxygen (O2) or
nitrogen (N2) molecules.
In the troposphere near Earth's surface, ozone is
even less abundant, with a typical range of 20 to
100 ozone molecules for each billion air molecules.
The highest surface values result when ozone is
formed in air polluted by human activities.

33. • As an illustration of the low relative abundance of ozone
in our atmosphere, one can imagine bringing all the
ozone molecules in the troposphere and stratosphere
down to Earth's surface and uniformly distributing these
molecules into a layer of gas extending over the globe.
• The resulting layer of pure ozone would have an average
thickness of about three millimeters (about one-tenth
inch).
• Nonetheless, this extremely small fraction of the
atmosphere plays a vital role in protecting life on Earth.
How is ozone formed in the atmosphere?
Stratospheric ozone formation
• Stratospheric ozone is formed naturally by chemical
reactions involving solar ultraviolet radiation (sunlight)
and oxygen molecules, which make up 21% of the
atmosphere.

34. • In the first step, solar ultraviolet radiation breaks apart
one oxygen molecule (O2) to produce two oxygen atoms
(2 O) .
• In the second step, each of these highly reactive atoms
combines with an oxygen molecule to produce an ozone
molecule (O3).
• These reactions occur continually whenever solar
ultraviolet radiation is present in the stratosphere.
• As a result, the largest ozone production occurs in the
tropical stratosphere.
• The production of stratospheric ozone is balanced by its
destruction in chemical reactions.
• Ozone reacts continually with sunlight and a wide
variety of natural and human-produced chemicals in the
stratosphere.
• In each reaction, an ozone molecule is lost and other
chemical compounds are produced.

35. • Important reactive gases that destroy ozone
are hydrogen and nitrogen oxides and those
containing chlorine and bromine .
• Some stratospheric ozone is regularly
transported down into the troposphere and
can occasionally influence ozone amounts at
Earth’s surface, particularly in remote,
unpolluted regions of the globe.

36. Ozone production in the stratosphere

37. The chlorine catalytic cycle that destroys ozone

38. Tropospheric ozone formation
• Near Earth’s surface, ozone is produced by chemical
reactions involving naturally occurring gases and gases
from pollution sources.
• Ground level or tropospheric ozone is created by
chemical reactions between oxides of nitrogen (NOx
gases),volatile organic compounds (VOCs) like
hydrocarbon and sunlight.
• The combination of these chemicals in the presence of
sunlight form ozone.
• Fossil fuel combustion is a primary source of pollutant
gases that lead to tropospheric ozone production.
• The production of ozone near the surface does not
significantly contribute to the abundance of
stratospheric ozone.
• The amount of surface ozone is too small in comparison
and the transport of surface air to the stratosphere is not
effective enough.

39. • As in the stratosphere, ozone in the troposphere
is destroyed by naturally occurring chemical
reactions and by reactions involving human-
produced chemicals.
• Tropospheric ozone can also be destroyed when
ozone reacts with a variety of surfaces, such as
those of soils and plants.
• Although tropospheric ozone is less
concentrated than stratospheric ozone, it is of
concern because of its health effects.
• Ozone in the troposphere is considered
a greenhouse gas, and may contribute to global
warming.

40. Balance of chemical processes
• Ozone abundances in the stratosphere and troposphere
are determined by the balance between chemical
processes that produce and destroy ozone.
• The balance is determined by the amounts of reactive
gases and how the rate or effectiveness of the various
reactions varies with sunlight intensity, location in the
atmosphere, temperature, and other factors.
• As atmospheric conditions change to favor ozone-
producing reactions in a certain location, ozone
abundances increase.
• Similarly, if conditions change to favor other reactions
that destroy ozone, abundances decrease.
• The balance of production and loss reactions combined
with atmospheric air motions determines the global
distribution of ozone on timescales of days to many
months.

41. • Global ozone has decreased during the past several
decades because the amounts of reactive gases
containing chlorine and bromine have increased in the
stratosphere due to human activities.
Why do we care about atmospheric ozone?
• Ozone in the stratosphere absorbs a large part of the
Sun’s biologically harmful ultraviolet radiation.
• Stratospheric ozone is considered “good” ozone because
of this beneficial role.
• In contrast, ozone formed at Earth’s surface in excess of
natural amounts is considered “bad” ozone because it is
harmful to humans, plants, and animals.
• Natural ozone near the surface and in the lower
atmosphere plays an important beneficial role in
chemically removing pollutants from the atmosphere.

42. Good ozone
• Stratospheric ozone is considered good for humans and
other life forms because it absorbs ultraviolet- B (UV-B)
radiation from the Sun
• If not absorbed, UV-B radiation would reach Earth’s
surface in amounts that are harmful to a variety of life
forms.
• In humans, increased exposure to UV-B radiation
increases the risks of skin cancer, cataracts, and a
suppressed immune system.
• UV-B radiation exposure before adulthood and
cumulative exposure are both important health risk
factors.
• Excessive UV-B exposure also can damage terrestrial
plant life, single-cell organisms, and aquatic ecosystems.
• Other UV radiation, UV-A, which is not absorbed
significantly by ozone, causes premature aging of the
skin.

43. Protecting good ozone
• In the mid-1970s, it was discovered that gases containing
chlorine and bromine atoms released by human activities
could cause stratospheric ozone depletion .
• These gases, referred to as halogen source gases, and as
ozone-depleting substances (ODSs), chemically release their
chlorine and bromine atoms after they reach the
stratosphere.
• Ozone depletion increases surface UV-B radiation above
naturally occurring amounts.
• International efforts have been successful in protecting the
ozone layer through controls on ODS production and
consumption.
Bad ozone
• Ozone near Earth’s surface in excess of natural amounts is
considered bad ozone.
• It is formed by reactions involving human-made pollutant
gases.

44. • Increasing surface ozone above natural levels is harmful
to humans, plants, and other living systems because
ozone reacts strongly to destroy or alter many biological
molecules.
• High ozone exposure reduces crop yields and forest
growth.
• In humans, exposure to high levels of ozone can reduce
lung capacity; cause chest pains, throat irritation, and
coughing; and worsen preexisting health conditions
related to the heart and lungs.
• In addition, increases in tropospheric ozone lead to a
warming of Earth’s surface because ozone is a
greenhouse gas.
• The negative effects of excess tropospheric ozone
contrast sharply with the protection from harmful UV-B
radiation afforded by an abundance of stratospheric
ozone.

45. Health effects of tropospheric ozone
• Health effects depend on ozone precursors, which is a
group of pollutants, primarily generated during the
combustion of fossil fuels.
• Ground-Level Ozone is created by nitrous oxides reacting
with organic compounds in the presence of sunlight.
• There are many man-made sources of these organic
compounds including vehicle and industrial emissions,
along with several other sources.
• Reaction with daylight ultraviolet (UV) rays and these
precursors create ground-level ozone pollution.
• Ozone is known to have the following health effects at
concentrations common in urban air:
Irritation of the respiratory system, causing coughing,
throat irritation, and/or an uncomfortable sensation in
the chest.

46. Ozone affects people with underlying
respiratory conditions such as asthma, chronic
obstructive pulmonary disease (COPD), and
lung cancer as well those who spend a lot of
time being active outdoors.
Reduced lung function, making it more difficult
to breathe deeply and vigorously.
Breathing may become more rapid and more
shallow than normal, and a person's ability to
engage in vigorous activities may be limited.
Ozone causes the muscles in the airways to
constrict which traps air in the alveoli leading
to wheezing and shortness of breath.

47.  Aggravation of asthma. When ozone levels are high,
more people with asthma have attacks that require a
doctor's attention or use of medication. One reason
this happens is that ozone makes people more
sensitive to allergens, which in turn trigger asthma
attacks.
 Increased susceptibility to respiratory infections.
Inflammation and damage to the lining of the lungs.
Within a few days, the damaged cells are shed and
replaced much like the skin peels after a sunburn.
Animal studies suggest that if this type of
inflammation happens repeatedly over a long time
period (months, years, a lifetime), lung tissue may
become permanently scarred, resulting in permanent
loss of lung function and a lower quality of life.

48. More recent data suggests that ozone can also
have harmful effects via the inflammatory pathway
leading to heart disease, type 2 diabetes, and other
metabolic disorders.
It was observed in the 1990s that ground-level
ozone can advance death by a few days in
predisposed and vulnerable populations.
A statistical study of 95 large urban communities in
the United States found significant association
between ozone levels and premature death.
The study estimated that a one-third reduction in
urban ozone concentrations would save roughly
4000 lives per year (Bell et al., 2004).
Tropospheric Ozone causes approximately 22,000
premature deaths per year in 25 countries in the
European Union (WHO, 2008)

49. Reducing bad ozone
• Limiting the emission of certain common
pollutants reduces the production of excess
ozone in the air surrounding humans, plants, and
animals.
• Natural emissions from the biosphere, mainly
from trees, also participate in reactions that
produce ozone.
• Major sources of pollutants include large cities
where fossil fuel consumption and industrial
activities are greatest.
• Many programs around the globe have already
been successful in reducing or limiting the
emission of pollutants that cause production of
excess ozone near Earth’s surface.

50. 3.4 The hydrosphere and climate change
• The hydrosphere is made up of water, in the form of gas
(water vapour in the atmosphere), liquid (fresh water in
rivers and lakes, and salt water in seas) and solid (ice in
glaciers and ice caps in the polar regions).
• The circulation of water in the hydrosphere is known as
the hydrological cycle (sometimes called the ‘water
cycle’).
• Evaporation from the sea and land adds water vapour
to the atmosphere, where condensation occurs turning
the vapour into liquid water which then falls
as precipitation (including snow, hail, rain and dew).
• If the precipitation falls onto land, it then passes over
and under the ground surface eventually to the sea.
This is shown in diagram form below.

51. The hydrological cycle. Source: Tal, 2016

52. • The level of water stored and transferred through the
hydrological cycle is an important indicator of climate change.
• The links between water and climate mean that changes to
water are both a cause and an effect of climate change.
Water as a cause and consequence of climate change: a positive
feedback loop
• Water vapour is itself a greenhouse gas.
• It can absorb heat in the atmosphere which in turn allows the
atmosphere to warm up.
• Water is so powerful that it can double the amount of
atmospheric warming caused by carbon dioxide alone.
• This means that if there is an increase in water vapour in the
atmosphere, it can increase heat which in turn allows for more
evaporation from water in the sea and on land, and therefore
more water vapour is added to the atmosphere.
• It can lead to changes in atmospheric conditions in cloud
cover, precipitation, as well as temperature changes.

53. 3.5 The biosphere and climate change
• The biosphere includes all the organic material on Earth.
• Organic matter is anything that is wholly or partly made of
living (or dead) things, so it is sometimes considered to
include the pedosphere which is soil.
• All living things exist within ecosystems, which are local-
scale units of interaction.
• Depending on the viewpoint of an environmentalist, the
scale can vary significantly from something as small as a
tree to as large as an entire forest.
• Collections of ecosystems with similar characteristics are
referred to as biomes.
• Another way to define a biome is a world scale ecosystem,
such as boreal forest, tropical rainforest, or hot deserts.
• In general, the distribution of biomes is closely related to
the distribution of climate.
• Climate itself usually varies depending on latitude and
altitude.

54. The main biomes in the world. Source: Koistinen, 2007.

55. • Changes in the biosphere can be a very long
term climate change cause – for example, over
millions of years the first green plants changed
the atmosphere by increasing the amount of
oxygen.
• However, in the short term (thousands of years)
the biosphere has to react to climate change.
• This can lead to animal migration, extinction and
changes in species dominance, as species that
are better suited to the new climatic conditions
take over.
• Marine biomes can also be affected. Marine
biomes are those under the sea and include coral
reefs and mangroves.

56. 3.6 The pedosphere (soil) and climate change
• The pedosphere refers to the soil layer of the Earth.
• The pedosphere is an important carbon sink.
• A carbon sink removes carbon from the atmosphere and
traps it.
• This is known as ‘fixing’ the carbon.
• Soil does this by trapping the carbon in plant tissue
(which the plant itself absorbed from the atmosphere
during respiration and photosynthesis).
• Soil degradation and the clearing of forest for farmland
(which itself can lead to soil degradation) is therefore an
important concern for climate change.
• Meanwhile, the soil can also be washed away by more
frequent rainfall, or dried out by dry weather and eroded
by wind.

57. • Humans have a huge impact on all spheres.
• Negative impacts, such as burning fossil fuels, pollute
the atmosphere.
• Piling up our waste in landfills affects the
geosphere/lithosphere.
• Pumping waste into the oceans harms the hydrosphere.
• And overfishing and habitat destruction can reduce the
diversity of living things in the biosphere.
• However, people everywhere are working to change
things.
• Recycling efforts are increasing all over the world, and
companies are finding new ways to reduce or replace
fossil fuels.
• In the US alone, people are recycling six times more
than a generation ago.