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Environmental Sustainability
Junior Science
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Water is important for life on Earth
Without water, there would be no life on
Earth. Water is continually moving
around, in the ocean, rain and rivers, but
the amount of water on Earth is fixed.
The water that exists on earth today is
the same water that existed billions of
years ago. On Earth and in the
atmosphere the water is continually
recycled, in a process known as the
water cycle. This cycle is important to all
species on Earth, including humans.
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We have a fixed amount of water on Earth that continuously changes into
different states – Water cycle
Water on Earth is always
changing. Its repeating
changes make a cycle. As
water goes through its
cycle, it can be a solid
(ice), a liquid (water), or
a gas (water vapor). Ice
can change to become
water or water vapor.
Water can change to
become ice or water
vapor. Water vapor can
change to become ice or
water.
The processes by which water in changed from one form into another
When water falls to the
earth as precipitation (rain
or snow), one of three
things may happen to it:
1. it may return to the
atmosphere;
2.it may soak into the
ground; or
3.it may flow over the
surface into a stream, lake,
wetland or the ocean.
Evaporation from these
water bodies and from the
soil returns water to the
atmosphere once again
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Water is stored on Earth in different forms
Precipitation (rain, snow) may fall on vegetation, mountains or human-made structures,
before reaching the ground from where it either evaporates into the atmosphere again,
or flows to the ground.
When water flows into the ground may be taken up by plant roots for use in
photosynthesis. The excess water diffuses through the openings in the leaves; this
process is called transpiration.
Water that is not taken
up by plants soaks into
the spaces between
soil particles and forms
groundwater. Large
collections of
groundwater are
called aquifers, and
these are sometimes
tapped with wells for
drinking or irrigation.
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Water is stored on Earth in different forms
Only 3% of Earths water is fresh water. Over two thirds of the fresh water is
locked up as polar ice and glaciers while the remaining third is mostly
ground water. That leaves only 0.3% of all of the Earths fresh water stored
as lakes, rivers and swamps.
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Water conservation
One of the biggest issues relating to the water cycle is the supply of drinking water and
irrigation water for growing food. Only 0.1% of all the total fresh water is accessible in
lakes, rivers and shallow groundwater. The rest is locked up in polar ice sheets or deep
underground, and is not available for drinking or irrigation.
Because such a
limited amount of
water is available
we must ensure we
use water
conservation
methods to
sustainably make
the best use of the
water we have.
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Water conservation
The amount of water that is
required to feed, clothe, house
and transport a person is known
as their ‘water footprint’.
Food harvested straight from
the ground such as fruit and
vegetables have a smaller water
footprint compared to meats
and processed food.
Generally the more steps a
product has to go through
before it reaches the consumer,
the larger the water footprint.
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The atmosphere is a layer of gases that surrounds the earth
The Earth's
atmosphere is an
extremely thin layer
of gases
surrounding the
surface of the Earth
reaching to the
edge of space. The
thickness of the
atmosphere is about
100 kilometres.
Gravity holds the
atmosphere to the
Earth's surface.
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The composition of gases that make up air and the atmosphere
The largest portion of gas that makes up the atmosphere is nitrogen – a vital
ingredient in plant growth but only once it is changed into it’s ion form. Oxygen
makes up just under a quarter of the atmosphere and it vital for life on Earth. Only
a very tiny portion of the atmosphere is made up of Carbon dioxide – required by
plants in the process of photosynthesis – but increasing amounts produced from
human activity are causing the planet to heat up.
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The structure of Earth’s atmosphere
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The atmosphere transports heat and water
Heat energy from
the Sun travels to
the Earth in waves.
The atmosphere and
clouds reflect some
of the heat energy
back out into space.
The heat energy that
reaches the Earths
surface is
responsible for
heating the planet
and creating the
weather.
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The atmosphere filters out deadly ultraviolet radiation
The Earths atmosphere contains a layer of gas called ozone – this is a molecule
made up of 3 oxygen atoms. The ozone layer prevents most of the ultraviolet (UV)
radiation that is emitted from the sun along with heat and light energy. UV
radiation can cause damage and mutations (such as cancer) in living organisms.
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The suns heat drives the weather
Different levels of heat on the surface of earth from the Sun is the main cause of wind,
along with the spin of the Earth.
The amount of heat input on any part of the Earth varies because of season, cloud cover,
latitude, and surface type. Ocean surfaces heat and cool slowly, Land heats and cools
quickly.
When one area
heats up the air
pressure rises, and
the higher
pressure air
expands and tries
to move into the
cooler lower
pressure areas.
Warmed air also
rises, while cooling
air sinks. All this
movement of air
causes wind.
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Differences in temperature and moisture (density) in the atmosphere
create movement of air particles
Clouds are made of condensed water or ice. All air contains water vapour - in
different amounts, called humidity.
Hot air rises and as it
does it cools. Cooler
air can no longer hold
all of the water
vapour it contains
and some of it
condenses to form
(visible) cloud
droplets or ice
crystals.
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Carbon dioxide is a greenhouse gas and traps heat in the atmosphere.
Without it and other greenhouse gases, Earth would be a frozen world
Earth’s climate in 4.5 billion-year has naturally changed between being very cold and
covered in ice, or very hot. In the recent 10,000 years the planet’s climate has become
much more stable, creating an ideal environment for humans and domestication of
plants and animals.
However, over the past 50-100 years, increasing human activity (such as industry,
agriculture and transportation) has begun to affect the natural climate balance. These
activities are increasing the amount of greenhouse gases in our atmosphere and causing
Earth to heat up faster than ever seen before since humans have been on Earth.
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Human activity is increasing the CO2 in the atmosphere and Earth is
becoming a warmer place
Around 1750, the period of
history called the industrial
revolution, humans began to
burn fossil fuels and produce
greenhouse gases in
increasing amounts. The
overall effect of human
activities on the climate has
been a warming influence.
According to scientific
studies, in the past 650,000
years the planet has never
had so much carbon dioxide
in its atmosphere as it does
today, and the levels of the
gas are continuing to rise.
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Human activity is accelerating climate change
Persistent human
activities like driving
cars, farming,
burning coal and
cutting down forests
produce greenhouse
gases – mainly
carbon dioxide,
methane and nitrous
oxide. These gases
gather in the
atmosphere, wrap
around the earth and
trap the sun's heat.
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Human activity is increasing the CO2 in the atmosphere and Earth is
becoming a warmer place
The carbon dioxide and
other greenhouse gases in
the atmosphere act as an
“insulation blanket”. With
not enough greenhouse
gases the heat from the
Sun would reach Earth but
then radiate away leaving
the planet to cold. With
too much greenhouse
gases the heat is trapped
around Earth and doesn’t
escape as easily making
the Earth to hot.
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Human activity is accelerating climate change
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The more greenhouse
gases we release, the
faster the world's climate
heats up. This process is
called global warming
but it also leads to
climate change because
it is increasing the
amount of floods,
storms, cyclones,
droughts and landslips.
Climate change is
affecting our economy,
environment and the way
we live – we are already
seeing the effects and
need to prepare for more
changes in the future.
Human activity is accelerating climate change
In New Zealand likely climate change impacts include: higher temperatures, more
droughts in some areas and floods in others, and a change in the amount of rain with
higher rainfall in the west and less in the east.
These changes in climate will cause a range of effects including changing agricultural
productivity where some species will not grow as well and other warm loving species
will need to be grown, warmer winters with fewer frosts, but hotter summers causing
heat stress and diseases in plants and animals, rising sea levels will effect coastal areas
and glaciers are expected to retreat.
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All living things are made of carbon and that carbon
changes from one form to another in a carbon cycle
Carbon exists in a
number of forms. It
is part of a gas
molecule called
carbon dioxide
found in the
atmosphere which
can be turned into
carbon compounds
in plants through
photosynthesis. This
carbon is then
passed along to
other living
organisms when
they are consumed
and released back
into the atmosphere
during respiration.
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All living things are made of carbon and that carbon changes from one form
to another in a carbon cycle
Natural processes of photosynthesis and respiration (blue arrows) keep the carbon
dioxide levels reasonably stable in the atmosphere – and therefore the global
temperature steady. Human activity such as farming, industry and burning fossil fuels
(red arrows) which have a large amount of “locked up” carbon are affecting this balance
and causing the levels of Carbon Dioxide to increase.
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Carbon can be stored in the Earth in ‘carbon sinks’ such as fossil fuels, rocks
and ocean sediments
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Increases in the human population has a negative impact on the Earth’s
resources
Increases in the human population
has resulted in:
>An increased demand for food,
materials and energy resources;
>An increased destruction of
habitats for industry, farming,
houses and roads;
>An increased need to dispose of
waste
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The activities of humans are leading to serious pollution problems
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The activities of humans are leading to serious pollution problems
Land pollution
Land pollution is caused
by the contamination
and degradation of the
land surface and soil of
the earth, due to unsustainable practice.
The activities of humans are leading to serious pollution problems
Water pollution
Water pollution is the
contamination of lakes, rivers,
oceans, aquifers or groundwater with
untreated waste.
The activities of humans are leading to serious pollution problems
Air pollution
Air pollution is contamination of the
environment by any chemical, physical
or biological waste that changes the
atmosphere.
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The Earth has a fixed amount of resources that have to be managed
sustainably
Sustainable means to
continue being able to do
something or use something
indefinitely. Some of our
resources on Earth are Nonrenewable such as coal, oil
and minerals and they will be
all used up eventually as the
process to make more takes a
very long time. Other
resources such as timber and
fish are renewable. As long as
we do not take to much and
replace what we use then
these resources can be used
for a long period of time
sustainably.
The Earth has a fixed amount of resources that have to be managed
sustainably
We can manage our
environment more
sustainably by:
>Introducing regulations
to reduce air pollution and
water pollution.
>Reclaiming areas
damaged by mining and
industry.
>Improved management
of habitats, nature
reserves and national
parks.
>Restrictions on the
number of wild animals
taken for food.
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