Humans and the Environment
Fire was one way that early humans changed
their environment. Fire was a good way to drive animals into
places where they could be killed for food and skins. Burning dead
grass puts nutrients into the soil so that new grass will grow more
quickly. Grazing animals will come to this rich grass and can
easily be hunted. When humans began herding animals and farming,
they made great changes in their environment. They cleared forests
and tilled the soil to kill "weeds" and make a good place for
seeds to grow. They put animals on pastures in greater numbers
than would occur naturally and changed the earth forever. The
Sahara Desert has grown in size because humans tried to farm and herd
cattle and goats close to its edge. When drought came, the topsoil
blew away and the land could not recover.
Humans have had the ability to change their
environment for thousands of years. Today this ability is greater
than ever. This is because there are more people living now than
ever before and human activity is concentrated in huge cities.
Also, science and technology allow us to interfere with natural
processes in more direct ways.
We now understand more about the
environment and how it works. Sometimes this understanding came
about after a problem had surfaced. The story of DDT is a
good example. DDT was introduced after World War II as a very
effective pesticide. DDT is broken down slowly through natural
processes. The DDT was washed into the soil and into rivers where
animals and plants absorbed small amounts of it. Birds, which are
at the top of the food chain, were greatly affected. The DDT caused
them to lay eggs with very thin shells. The eggs did not
survive. Ospreys, eagles and falcons were particularly affected by
DDT. When DDT was banned, these birds made a dramatic recovery but
DDT residue is still found in every environment on earth.
Pollution problems are not just problems of
the air, water, or soil. Pollution affects all parts of the
environment. When we put something into the environment, it
doesn't just go away. The pollutant eventually becomes part of the
environment. When a toxic chemical enters our lakes and
rivers, it
doesn't just stay there. It enters the plants and animals that
live in the water. It may enter drinking water that people
use. It may get into the soil through irrigation. Eventually
it is washed into the ocean where fish and other creatures may become
contaminated. If we eat these fish, we too become
contaminated. Serious diseases, like cancer, could be associated
with pollution.
Some environmental problems are not easy to
see. Not all pollutants cause immediate or short-term
problems. It may take years of exposure or build-up before any
effects are seen. A good example is the accumulation of carbon
dioxide in the air. One of the by-products of combustion is carbon
dioxide. For over a century man has been burning huge amounts of
coal, oil and gas. Research suggests that we have burned so much
that we have increased the amount of carbon dioxide in the air.
Carbon dioxide absorbs heat. A small increase in the amount of
carbon dioxide will increase the temperature of the earth. This is
called the "enhanced greenhouse effect". A rise of the
average annual temperature of 3 degrees Celsius would make most of the
prairies unsuitable for agriculture. It would be too dry.
This same rise in temperature would start melting the polar ice
caps. The world's sea coasts could be flooded by several metres of
water.
The better we understand the earth, the
better we can understand the problems that face us. An
environmental viewpoint is one way of looking at the earth. This
way of looking at problems goes beyond immediate questions and looks at
how they affect the whole environment. A functioning, well balanced environment is
important humans. We need clean air to breathe, clean water to
drink, food to eat, and shelter. All these things are part of our
environment and are interconnected. We now know that if we pollute
our air we may be affecting our food and water supply.
Governments, industry, and public groups
all recognize the need to manage and protect the environment so that it
continues to provide the necessities of life. Scientists in
government and industry research environmental problems. New
information is used to make new regulations or devise new processes
which improve environmental quality. Public groups tell government
and industry of their concerns and interests. Each of us has a
part to play in this process.
The planet Earth is the only place we know
of in the whole universe where mankind can live. We need to take
care of it.
Reprinted from Focus On Environment
(1993) with permission of Alberta
Environment.
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