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Science Matters by David
Suzuki
Most Canadians today live in large cities — human-created habitats
filled primarily with other people, a few pets and domesticated plants.
So it’s not surprising that I am often asked, "Who needs
nature?"
The answer is "We all do," and I will try to show why. Let
us imagine that scientists have made a breakthrough and created a
time machine. Suppose we board the machine, dial four billion years
ago to a time when no life existed. We push a button and zip, we are
immediately taken back to a sterile Earth. Anxious to see what the
planet was like, we open the door, step out — and within two
minutes, we would be dead.
The reason? The atmosphere was completely toxic back then - rich in
carbon dioxide and devoid of oxygen. After life arose some 3.8 billion
years ago, marine organisms began to absorb the carbon dioxide dissolved
in the oceans in order to make protective carbonaceous shells. When
they died, those organisms sank to the ocean floor where, over millions
of years, they became limestone. All of the world’s limestone
is made of carbon dioxide removed from the atmosphere.
But removing carbon dioxide wasn’t enough. We also need oxygen,
which was added to our atmosphere by organisms through photosynthesis.
Over millions of years, oxygen has accumulated to make up 19 per cent
of our air. To this day, photosynthesis on land, in soil and in oceans
maintains the balance of carbon dioxide and oxygen in the atmosphere
that we need to live.
Well, suppose we had anticipated the lack of breathable air and stored
tanks of it in the time machine. So we don the breathing apparatus
and leave the capsule to check out the land. After a few hours, we’d
get thirsty. But where would we find clean water to drink? Roots of
trees and other plants, soil fungi and microorganisms filter out heavy
metals and other toxic contaminants to clean our water. Again, before
life existed, water would have accumulated substances that we would
not care to drink. To this day, the web of living things filters our
water as it percolates through soil.
OK, so we brought clean water. But after hours of exploration, we
would also be hungry. Where would we find food? Every bit of the nutrition
we require for our bodies was once living. Four billion years ago
before life arose, there would have been nothing to eat.
Even if we brought food with us, we would need to include seeds if
we wanted to grow anything. But where could we plant them? Soil is
created from the carcasses of plants and animals mixed with a matrix
of dust, silt, sand, clay and gravel. So before there was life, there
was no soil. To this very day, besides being our food, other living
organisms create the soil on which we depend.
Finally, suppose after a long day, the sun sets and we would like
to have a fire. Where would we find fuel? Heat liberated from fuel
is sunlight captured and stored by plants. Like our food, every bit
of our fuel — wood, peat, coal, gas, oil — was once alive,
so four billion years ago, there was none to be found. Even if we
brought wood with us, heaped it on paper, then struck a match to light
it — nothing would happen. In order to have a flame, we need
oxygen and before photosynthesis, there was no oxygen.
Now let’s reconsider the question, who needs nature? We do —and
in a most profound way. The web of all life on Earth, through mechanisms
we are far from understanding, creates, cleanses and replenishes the
air, water, soil and energy that we need to survive. We have never
needed nature more than we do today.
To discuss this topic with others, visit the discussion forum
at davidsuzuki.org.
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