The earth today is a giant laboratory in which humans are conducting
thoughtless experiments that could have catastrophic consequences.
We need to think about how the earth and its subsystems of living and
nonliving parts operate, how we disturb the system, and how to improve
the forecasting of our impacts on the environment.
Small ‘scale individual actions may seem harmless, but when carried
out globally their total effect can add up to serious trouble for the environment. One widely predicted catastrophe of global warming is a rise
of sea levels, which would bring economic ruin to many coastal
communities.
Warmer climates could extend growing seasons in colder places like
Canada; poorer countries, which tend to exist in the World’s hottest
regions already, would suffer greater economic inequity.
OCEANS WILL RISE.
Rising global temperatures will shrink glaciers over the coming
decades, causing sea levels to rise around the world. Europe’s glaciers
have been in slow retreat for a century or more; satellite assisted
measurements are expected to reveal, within a few years, whether the
polar ice caps are melting.
A sea level rise might put many coastal areas permanently under
water, but the biggest near term threat may be storm surges.
If the earth becomes warmer the ice on the poles will melt and certain
areas will become too hot to live in. This means that there will be more
water in the oceans and coastal areas like Karachi, Bombay and one third
of Bangladesh will sink. If animal species are destroyed, those animals
which eat them will also be destroyed. The balance of the ecosystem will
be upset and man too will die. If too many chemicals are used to spray our
crops they will be poisoned and many useful insects will be killed.
BLACK MARKET IN ENDANGERED SPECIES EMERGES.
Between $10 and $20 billion in plants and animals were traded
illegally around the world in 1996, with the United States leading the list
of buyers.
The black market in rare species includes butterflies and beetles killed
for collectors, potions made from the horns of black rhinos and the bones
of tigers (both said to increase male sexual potency), exotic skins used in
designer clothing, and Brazilian monkeys, Indonesian reptiles, and
Australian birds, sought by pet enthusiasts. On the black market, an
orang-utan can fetch up to $50,000, a hyacinth macaw up to $20,000, and
a Madagascar plowshare tortoise up to $20,000..
MANAGING NATURE.
Small restoration projects are under way to repair the damage done to
nature by human activities.. One of the new concepts is the oxymoronic
“managed natural zone. “This is a small protected area among at preserving individual rare species. Conservationists say the concept does
not transfer well regionally, but they have to be grateful for what they can
get these days.
Despite enormous efforts, conservationists have managed
but slow or redirect forces that have proved almost universally destructive
of wild nature.
The industrial revolution wrenched man away from the land
increased his power over nature. For nearly a century the human race
insanely plundered the earth. Forests were chopped down to make
furniture houses, print billions of useless books and other useless things.
Animals were hunted for fur, ivory tusks, skins and flesh till whole
species were wiped out. Above all our factories belched out smoke which
the Victorian novelists describe so well. But what the Victorians did not
I know is that the blackened buildings of the city only look ugly. The real
ugliness is that the ozone layer is destroyed.
The lethal rays of sum, which are otherwise blocked, come down and
give us skin cancer. People saw the litter in the Thames but not the sea
which, as the session on marine pollution made clear, is becoming
cesspool. And if the sea dies we will also die. Not only because the sea
I has fish but also because it produces oxygen as do forests. And when we
produce all those gadgets we can do without we produce lethal gases
which form a blanket which trap the heat of the earth. This raises the
temperature of the earth. This raises the temperature of the earth which is
called global warming.
Everyone wants to reduce pollution. But the pollution problem is as
complicated as it is serious. It is complicated because much pollution is
caused by things that benefit people. For example, exhaust from
automobiles causes a large percentage of all air pollution. But the
automobile provides transportation for millions of people. Factories
discharge much of the material that pollutes air and water,, but factories
provide jobs for people and produce goods that people want. Too much
fertilizer or pesticide can ruin soil, but fertilizers and pesticides are
important aids to the growing of crops.
Pollution of the environment has become a major concern during the
20th century as human society has generated an ever increasing variety
and quantity of products and wastes, many of which are released into the
environment. Land, water and air are all increasingly affected by a range
, of pollutants including noises, heat, smoke, chemicals, sewage, manure
and radioactive isotopes. Once in the environment, many pollutants are
dilute, dispersed or broken down into harmless materials, but others may be concentrated or transformed into more damaging forms. Damage
caused by pollution may not be immediately obvious, causing
comparatively subtle but far reaching changes in biological communities
which are not of obvious importance to humans and their environment.
However, the nature of the ecosystem is such that minor fluctuations may
be magnified by the interactions between species: for example, the
detrimental effect pesticides can have on bird populations. Monitoring
pollution pathways and effects is a formidable problem for environmental
scientists, but solving pollution problems is more than a technical issue.
Pollution occurs where human activities introduce something into the
environment which has harmful effects. The inclusion of harmful effects
in the definition means that the concept of pollution is value dependent and
hence politically contested. In many cases, values and interests differ: for
example, farmers use weedkillers and pesticides and regard the results as
beneficial, while conservationists lament the effects on meadow plants or
butterflies. In other cases it matters where the substance is: depletion of
stratospheric ozone is regarded as a problem, and so is increased low level
ozone. In some cases sulphur dioxide in the air acts as a valuable source of
plant nutrients while in others it contributes to acid rain and plant damage.
Concentration of pollutants makes a crucial difference: carbon dioxide
would not have been regarded as a pollutant a decade ago but now it is
involved in one of the most threatening pollution issues. In small
quantities, animal manure is beneficial, but in large quantities it can
overwhelm the capacity of natural cycles to deal with it. For most
chemical pollutants, and even for radioactivity, harmful effects may be
difficult to demonstrate at low concentrations so there may be passionate
disputes between emitter and affected publics. In many such cases there
may be natural sources of the possible pollutant as well as industrial
sources so responsibility is difficult to prove. Although governments seem
increasingly concerned to regulate pollution, progress is far from simple,
which is illustrated by some examples from air, water and land.
Acid rain has become an international issue, but ozone depletion is
truly global. It was a largely unexpected problem because the cause was a
I was strongest through a quite unexpected route. The stability of the
family of chemicals chosen for their safety and stability, and the effect
chlorofluorocarbons (CFCs) was ideal for refrigerators and aerosols, but it
allowed them to spread throughout the atmosphere and into the
stratosphere where ultraviolet light from the Sun broke them down. The
chlorine released proved extremely effective at breaking down ozone,
especially in the special conditions of the Antarctic spring, where more
than half of the ozone was lost. The surprise at the extent of damage, plus fear of skin can er from increased exposure to UV radiation
at the
surface, has made e international response unusually energetic, but there
are still problems i preventing CFC use from spreading into the Third
World. The problen. of global warming is an even more challenging
global issue, because its causes are integral to the nature of modern
society.
Land pollution occurs in three main ways:
(1) Mining and mineral processing may produce large voids and spoil
heaps. These are at least unsightly and spoil has the potential to cause
weathering processes which transform sulphides into dissolved acid. In
significant pollution. The entry of air and water into spoil heaps may cause
turn, increased acidity can dissolve metals, some of which are toxic. For
example, in acidified water courses it may be dissolved aluminium which
kills fish rather than the acid itself.
(2) The sites of manufacturing plants may become contaminated by raw
* materials, combustion products and wastes over the yeas they are running.
Any attempt to redevelop the site may encounter asbestos, toxic metals or
hazardous solvents.
(3) More pervasive, and often less identifiable, are the problems
associated with landfill sites. Many old dams contain chemical and metal
wastes as well as house hold refuse. Water percolating through such
dumps may dissolve toxic materials, producing leaches which contaminate
water courses. More pervasive still is the decomposition of organic
materials to produce methane, a gas which is explosive when mixed wit
ir and which is a very effective greenhouse gas. Modern landfills can b
anaged to reduce water percolation and to collect methane for use as
fuel, but many old dumps are unrecorded and potentially hazardous.
Pollution control is partly a matter of improving technology, for
ample, incineration of domestic waste can solve the problem of methane
n landfalls, as well as generating useful amounts of electricity, but
adoption of improved controls may be costly and may require political
pressure. Several different principles have been used or proposed. In the
UK, the Alkali Inspectorate relied for decades on the principle of Best
Practicable Means, that is the use of methods which would reduce
pollution but not put the polluters out of business. More recently this has
evolved into the Best Practicable Environmental Option and then the Best
Available Technology Not Entailing Excessive Cost. Most Europe
countries have preferred to set Emission Limits for pollutants and the EC
has moved toward imposing the same limits across its territory to provide
a level playing field for competition. The UK, with the advantage of a westerly airflow and rather short rivers, has objective that these limits are
discussed. This is the Prevention Principle, which seeks to prevent
coping with the
pollution from occurring rather than limiting it or
would bear very heavily on industry and face
consequences. As this
problems of predicting whether or not pollution would occur in particular
circumstances its progress will probably be slow.
THERMAL POLLUTION is a form of environmental pollution caused
by the release of waste heat into water or air. Electric power plants are a
major source of thermal pollution. In these plants, only about one third of
the energy in the fuel is converted into electricity, and the remaining
energy is released as heat to the local environment into water pumped to a
river, lake, or other waterway or into the air as hot exhaust gases. The.
entrance of this waste heat into the environment may have serious
consequences.
EFFECTS
Heat introduced into water can make the water so hot that no living
thing can survive in it. In water above 140° F (60°C) it is very unusual for
algae or bacteria to live, and serious problems occur at even much lower
temperature levels. Unlike warm blooded animals, fish and other cold
blooded organisms do not have a regulatory mechanism for maintaining a
fixed internal body temperature. Therefore when water temperate changes,
the body temperatures of the organisms also change. The resulting thermal
stress may be lethal to some species. Factors such as diet, age, previous
temperature exposure, weather, season of the year, and chemical
composition of the water may change the specific lethal temperature point
for fishes. Under certain conditions, for example, brown trout cannot live
in water at a temperature above 79° F (26°C). However, some hardy fish,
often known as “rough” fish, can survive in even higher temperatures
carp, for example, can live at 95° F (35°C) water temperature
Even comparatively small temperature increases may have serious
results, affecting, for example, reproduction in aquatic organisms. For
example, the natural rise in water temperature during the spring causes
female oysters and clams to shed their eggs. A similar, but artificially
produced, temperature rise at a different time of the year can trigger the
release of immature eggs. Excessive temperature can also prevent the
normal development of certain eggs. The Oregon Fish commission has
reported that a rise of only 5.4° F (3° C) in the Columbia River could be
disastrous to the eggs of the Chinook salmon. Increased temperature may
also affect hatching time in certain species. For example, herring eggs normally hatch in 47 days at a temperature of 32° F (0.° C). When the
Such an early hatching often results in smaller adult size and shortened life
water temperature is raised to 58° F (14.5° C) the eggs hatch in 8 days,
span.
SOLUTIONS
pollution from major industrial sources. One is a cooling pond into which
Several engineering solutions are available to minimize thermal
cooling pond permits evaporation of some water, carrying heat into the air
heated wastewater is released before it enters a natural waterway. The
I might, however, under some conditions, condense, producing fogs where
and this releasing cooler water into the water way. The evaporated water
none existed before. In addition, the evaporation from the cooling pond
might deprive the waterway of significant amounts of water, which could
be serious during summer month when the natural flow in a river is low.
Another possible solution to the problem of thermal pollution is the
cooling tower either wet or dry which also transfers heat to the air. In both
types, heated, water is introduced into a tower through which air is
blown,
and some heat is passed to the air. In wet towers, water and air are in
contact, resulting in water loss. In dry towers, a device like a car
arries the heated water, and less water is lost.
radiator
Several suggestions for the beneficial uses of thermal pollution have
jeen made. Among them is the possible use of heated water under fields
to lengthen the growing season for certain crops, under city streets in
winter to melt snow, or in cold estuarial areas to increase growth of fish
and shellfish. At the moment, these schemes are untested on a large scale.
All solutions must consider the general health of the environment as well
as energy use patterns, overall population growth, and other factors.
Water pollution is one of our most serious environmental problems. It
occurs when water is contaminated by such substances as human and other
animal wastes, toxic chemicals, metals, and oils. Pollution can affect rain,
rivers, lakes, oceans, and the water beneath the surface of the earth, called
ground water.
Polluted water may look clean or dirty, but it all contains germs,
chemicals, or other materials that can cause inconvenience, illness, or
death. Impurities must be removed before such water can be used safely
for drinking, cooking, washing, or laundering. Even some industries must
clean the water before it can be used in their manufacturing processes.
Water pollution has become a serious problem in most countries,
including Canada, China, India, Japan, the Soviet Union, and the United States. Governments have passed laws limiting the amount and kinds of
waste that can be dumped into water. Governments, industries, cities, and
towns have spent billions of dollars on research and water treatment plants
to reduce pollution. But there are still serious problems. In the United
States, several large cities, including Boston and New York City, release a
huge volume of untreated sewage into their harbours or coastal waters.
Also, pollution that does not come from a direct point, such as a sewage
outlet or factory drain, is largely uncontrolled. These non point sources of
pollution include water that runs off construction sites and farmland and
carries sediment (soil particles) and nutrients into streams and lakes.