HUMAN IMPACT ON THE ENVIRONMENT



     For most (over 90%) of our history as a species we have impacted 
little on the environment in which we lived.  Our primitive ancestors 
existed as nomadic hunters and gatherers who neither built permanent 
dwellings nor remained in an area long enough to exhaust its resources.  
With the discovery of agriculture, however, this situation changed for 
the worse.  When our later ancestors learned to cultivate crops and 
domesticate animals, they settled down to a more permanent existence 
and began to change the environment around them.  They cleared areas 
for raising crops and animals and their crops depleted the soil of 
nutrients while the grazing of their sheep, goats and cattle interrupted 
the normal sequence of ecological succession and so prevented 
reforestation.  Both practices of farming and animal husbandry 
contributed an excess of food which resulted in a population explosion.  
As population size increased people began to settle into larger 
communities and cities were born.  Released from the need to spend 
most of their time seeking food, these early city-dwellers began to 
specialize in trades and the consequent division of labor did much to 
enhance the quality of life.


     Through technological innovation we passed through the Bronze Age 
and the Iron Age into the Golden Ages of Greece and Rome which laid the 
foundation for the spectacular rise of Western civilization.  During all 
this time, except for occasional setbacks due to epidemic disease and 
warfare, our population size increased.


     Over time this population explosion had negative consequences.  Poor 
farming practices damaged the land as did overexploitation of forested 
areas.  The Middle East, famed for the cedars of Lebanon and the 
Promised Land overflowing with milk and honey, was converted into a 
desert (assisted by a change in climate).  In poorer areas today, e.g., in 
Africa and China, these practices are still ruining the land.  To keep 
warm and to cook the inhabitants lay waste to forested areas in search 
of firewood, and when this is gone, they use the dung of domesticated 
animals for fuel.  This practice has two negative effects: it removes a 
valuable fertilizer so that the land continues to deteriorate and crop 
production declines, also the loss of trees and shrubs results in 
massive soil erosion which renders the land useless.


     With the invention of machines and engines powered by steam, the 
pace of life quickened as we moved into the period of the Industrial 
Revolution.  Now for the first time we began to notice a change in 
society during the span of a single human lifetime, and the rate of 
technological change is still accelerating.  People alive today have 
witnessed the invention of the airplane and subsequent developments 
leading to our present space age.  This rate of technological change has 
not abated so we can expect to see even more human-made wonders in 
the coming decade.  Each decade has produced a marked improvement in 
the quality of human life.  The nostalgic yearning for a return to the 
"good old days," when the pace of life was more leisurely, is but a trick 
of faulty memory which retains the good aspects of former days while 
blotting out the negatives.  No seriously reflective person would opt for 
the past given the quality of human life which exists today as the fruit 
of modern technology.  In general, up to now the present has always 
been better than the past in terms of the quality of human existence!


     I say "up to now" because we can see for the first time substantial 
negative consequences associated with technological progress.  First 
and foremost is the effect of continued population expansion which 
undercuts improvements brought about by technology.  The single source 
of human misery today is poverty associated with reource limitation 
and overpopulation.  Planet Earth now contains 5.2 billion people and 
that number is growing fast.  By the turn of the century it will have 
grown to 6 billion.  How many humans can this planet sustain?  Some 
argue that we have already exceeded the carrying capacity of the 
environment and the decline in the quality of life experienced by Third 
World countries, where the rate of population increase is greatest, 
bears witness to this argument.  


     In addition to this most serious problem we are now coming to 
realize that technological advancement is purchased at a cost to the 
environment.  The burning of fossil fuels (coal, natural gas, gasoline) 
has provided the energy to power the factories which produce the goods 
that contribute to our high standard of living, to heat and cool homes, to 
generate electricity for running appliances and to drive the 
transportation vehicles which characterize our modern age; but this 
combustion releases noxious gases into the atmosphere which 
contribute to acid rain, the depletion of the ozone layer and the 
greenhouse effect.  Indiscriminate use of pesticides and fertilizers has 
poisoned our water supply, damaged the productivity of rivers and 
lakes, and resulted in a serious build-up of toxins in the fish and meat 
we eat.  Our waste products in the form of garbage and trash have 
accumulated to such an extent that we are running out of space to 
contain them safely and improper disposal in the ocean threatens the 
stability of one of the planet's most delicate ecosystems.


     To provide food for our growing masses we are cutting down tropical 
rain forests to produce farms and pastures which will be shortlived due 
to the poor soil conditions.  This destruction continues globally at a 
rate such that an area the size of the state of Ohio is cleared each year.  
In so doing, however, we are destroying ecosystems which took millions 
of years to evolve, which contain by far the greatest number of species 
on this planet and which will never recover once destroyed.  Our 
deforestation efforts rival past geological catastrophes in the number 
of species which will become extinct, and among them will be plants 
that produce medically valuable chemicals.  Changes in local climate 
due to the conversion of rain forests to open land most likely will have 
far reaching, but as yet unpredictable, effects on global climate 
patterns.


     We have the technological might to move mountains, but lack the 
knowledge to predict the ecological consequences of such power.  Our 
attempts to irrigate deserts have met with failure as the land which 
does produce crops for a while becomes too salty and returns to a 
desert.  Such an unforeseen result should serve as a warning: we cannot 
perform experiments on such a scale without a firm understanding of 
their consequences.  But, such experiments might be required in an 
effort to accommodate larger population size. We have already 
experimented with the atmosphere as can be seen in the greenhouse 
effect and ozone depletion by chlorofluorocarbons (CFCs) used as spray 
propellants, cleaning solvents and air-conditioning chemicals.  Now we 
must sit back and await the results of our experiments, for there is 
little we can do to correct the situation. Given our present lack of 
knowledge about the dynamics of the atmosphere, our main hope for the 
future lies in preventing further atmospheric deterioration.


     Our ignorance surpasses our ingenuity.  Forgetful of the power of 
nature we have overdeveloped the East coast from New England to 
Florida and now are vulnerable to the physical damage and loss of life 
that will accompany above average hurricanes that surely will hit in the 
future.  We build cities on fault lines and wonder why earthquakes are 
so devastating.  The suburbs of Aukland, New Zealand have been built 
around volcanic craters once thought to be extinct, but which in the 
light of plate tectonic theory we now know are as active as any time in 
past geological history. Our growth in wisdom has not kept pace with 
our advances in technology, and unless we recognize the fact that we 
are the major instrument of change on our dynamic planet, our survival 
prospects are about as good as those of a baby playing with a loaded 
pistol.


     Of all the species that have ever existed, we alone have a capacity 
for conscious foresight, i.e., we can plan for the future and predict (to 
some extent, anyway) the consequences of our actions.  With this ability 
comes responsibility for our actions.  How will we be judged by future 
generations if we persist in abusing this ability through shortsighted 
and selfish overexploitation of our limited resources?  We are 
sacrificing short-term gain for long-term environmental degradation; 
and unless we change this attitude, we could be doomed to extinction or 
lower the quality of life for our grandchildren to an intolerable level.  
In us, evolution became conscious of itself; it would be tragic if this 
insight resulted in an undoing of the glorious achievements of the past 
3.5 or so billion years through our apathy, or even worse, through our 
greed.