Aside from monetary losses, air pollution eats at beloved cultural treasures.
In Athens I sat on a stone and contemplated what has been called the most
beautiful building in the world. Acid deposition has caused more erosion
on the marble Parthenon in the past 24 years than had occurred in 24 centuries.
The Roman Colosseum, Westminster Abbey, and the Taj Mahal are suffering
similar damage. At Chartres, as with other cathedrals, stained-glass windows
dating from the 12th and 13th centuries have corroded to barely recognizable
images. Is combustion our contribution to the arts?
The sources of damage are not easily removed. Legislation lags because
fumes come from industries badly needed for national economies, from automobiles
prized for private transportation, and from high-sulfur heating oils. Besieged
by budget-conscious citizens and profit-conscious industries, politicians
fiddle with regulations while their Romes burn.
The problem goes far beyond buildings and cities. Our entire troposphere
is a blue balloon from which there is little escape. Some pollutants degrade
or change form, but others may drift for years.
Careless neighbors
ONE NATION'S pollution may become another nation's problem. Most emissions
from North America's industrial heartland fall nearby on the north-eastern
U.S. and eastern Canada, as seen in a global model (top). A small percentage
rises high enough to be carried long distances.
Near their sources, some gases and particles may drop directly to earth
(diagram, above). Others are washed from the sky later by rain, snow, or
mist. But chemicals such as chlorofluorocarbons that do not dissolve or
recombine at higher levels may contaminate the stratosphere.
Clouds over the Amazon in Brazil are profiled in
a lidar image (below), made by bouncing a laser beam off particles in the
air.
Thunderstorms can gather smoke and other organic particles near the
surface and pump them higher into the atmosphere.
Like time capsules of the atmosphere, ice cores from a Yukon glacier contain information about air quality before the industrial revolution. By analyzing trapped air bubbles, a research team including Dr. Gerald Holdsworth (top) has learned that carbon dioxide levels in today's atmosphere are 27 percent higher than they were before 1850.
An ice sample from a glaciated plateau on Mount Logan (above) seems to bubble like club soda. Individual ice crystals take on different colors according to the angle at which polarized light strikes them.
For a portrait of our atmosphere, U. S. scientists sample the air at
four "clean" locations in a federal program called Geophysical Monitoring
for Climatic Change.
What sweeter air than atop one of Hawaii' 5 volcanoes, 13,680-foot
Mauna Loa? Meteorologist Elmer Robinson drove me up its bare shoulders
through lava fields sometimes jagged as cinders, sometimes smooth as swirled
chocolate. In bright sunlight we looked down at clouds raining on the town
of Hilo, far below.
On Mauna Loa's dry, primordial landscape nothing sprouts but technological
wizardry. The air is tasted with tongue-twisting nephelometers, transmissometers,
and spectrometers to better understand the aerial porridge that now surrounds
us.
The heavens are probed with laser light to see what particles are drifting.
Dust from China reaches here, and a mystery cloud once appeared whose source
was never identified, the stuff of science fiction.
For a view more mesmerizing than any fantasy, I mounted a ladder to
a telescope aimed at the morning sky. A large, black obscuring disk loomed
in the eyepiece to protect my retina, but at its edges flickered the light
of hidden energy -- the burning sun. Here, seemingly within arm's reach,
was the engine that drives this planet, hurling gases thousands of miles
into space. Is that life-giving heat now perilously altered on earth?
"One of the longest continuous records of CO2 content of the air is
kept here," said Mr. Robinson, director of the Mauna Loa Observatory. "We
find an increase of 27 percent since the mid-l9th century. CO2 holds heat
close to the earth, so the greenhouse effect is not a wild idea, it's pretty
basic physics."
The greenhouse effect, with potential for altering climate, melting
the polar ice caps, and raising ocean levels, has been called one of the
most serious long-range environmental issues. Suddenly, it's short-range.
"The most significant thing we've seen in the past few years has been
the increase in other greenhouse gases-methane and the chlorofluorocarbons,"
said Mr. Robinson.
"With the addition of these gases we may begin to see the effects around
the turn of the century," says climatologist J. Murray Mitchell, Jr., of
McLean, Virginia, who analyzes data sent from Mauna Loa.
All gases thickening the greenhouse are believed due to human activities.
Combustion gives off CO2. Methane, escalating by 2 percent a year, is attributed
to gases from livestock manure, additional rice fields, and digestion of
termites proliferating on dead wood left by worldwide clearing of forests.
The chlorofluorocarbons are a two-edged sword. Used as refrigerants
and, in some places, still used as spray-can propellants, they add to the
greenhouse as they drift upward. When they reach the stratosphere, they
are believed to react destructively with the gauze of ozone that protects
us from excessive ultraviolet rays. A sharp rise in ultraviolet rays would
increase melanomas and other malignant skin cancers and reduce crops. Melanomas
have doubled worldwide in recent years, but scientists are unable to connect
that fact directly to ozone depletion. It may be simply that people are
spending more time outdoors.
A warmer, wetter earth, or one more seared by sun? We are not just
polluting, as bad as that may be, we are tampering with basic weather-making
components of our atmosphere without knowing the outcome.
THERE IS mounting evidence that our whole planet is involved. The South Pole seems fairly clean because 90 percent of earth's population lives in the Northern Hemisphere. Yet in late 1985 scientists monitoring the stratosphere detected a major hole in the protective ozone screen over Antarctica.