=======================Electronic Edition========================
RACHEL’S ENVIRONMENT & HEALTH WEEKLY #466
—November 2, 1995—
News and resources for environmental justice.
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Fax (410) 263-8944; Internet: erf@rachel.clark.net
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CLIMATE AND INFECTIOUS DISEASE, PART 1
Inside a greenhouse, it is the glass roof that creates the
warmth. The glass lets sunlight stream in. When the sunlight
strikes a surface and turns into heat energy, the heat then
radiates back toward the sky. The radiated heat strikes the
glass, which has the peculiar property of allowing light to pass
through much better than it lets heat pass through. Therefore,
some of the heat is reflected back down into the greenhouse, and
the greenhouse warms up.
For at least 100 years, physicists and chemists have known that
carbon dioxide (CO2) in the atmosphere acts like glass covering
the earth. [1]CO2 lets sunlight in, but does not let heat out
nearly so well. Since 1850, the carbon dioxide content of the
atmosphere has increased 30% because of humans burning coal and
oil. There is nearly universal agreement among scientists that
this will warm the earth. [2] It’s only a question of when.
Now evidence is accumulating steadily, indicating that the
warming has begun:
** AIR IS WARMING: Global average air temperature over the last
century has risen about 0.8 degrees Fahrenheit (F.), which is
0.45 degrees Celsius (C.), according to the Intergovernmental
Panel on Climate Change (IPCC). The IPCC is made up of about 200
of the world’s leading scientists who specialize in climate
studies. In some areas, such as Australia and New Zealand, the
increase in air temperature has exceeded the average; in New
Zealand, average air temperature has risen between 0.7 and 1.4
degrees F. (or between 0.4 and 0.8 degrees C.). [3]
** OCEANS ARE WARMING: In November, 1994, researchers announced
finding a 0.9 degree F. (0.5 degree C.) rise in the temperature
of the deep waters of the Indian Ocean, compared to measurements
taken 20 years ago. This was the third ocean observed to be
warming. In 1992 Nathan Bindoff reported that the subsurface
temperature of the southwestern Pacific Ocean had increased at
about the same rate (0.9 degrees F. [0.5 degrees C.] over 20
years). [4] In early 1994, a group led by Gregorio Parrilla of
the Spanish Oceanographic Institute reported that the North
Atlantic was also warming. [5]
** In December, 1994, Ed Carmack of the Institute of Ocean
Sciences in Sidney, British Columbia, Canada, reported that the
waters 200 to 1000 meters (660 to 3280 feet) beneath the Arctic
Ocean have warmed 1.8 degrees F. (1.0 degrees C.) “compared to a
few years ago.” “There is clear evidence that the arctic is
warming,” Carmack reported. [6] The Arctic is thus the fourth
ocean found to be measurably warming. In June, 1995, researchers
used a new technique to measure temperature beneath the Arctic
ice cap. They measured the speed of sound through Arctic waters,
and from that calculated a warming of 0.9 degrees F. (0.5 degrees
C.) compared to thermometer data from a decade ago. [7]
** GLACIERS ARE MELTING. For example, on Mount Jaya in New
Guinea, three glaciers have shrunk by 6.2 square miles (16 square
kilometers) since 1936, and now only 1.1 square miles (3 square
kilometers) of ice remain. “The region has heavy snow showers,”
says Geoff Hope of the Australian National University in
Canberra, “so the shrinking must be due to a rise in
temperature.” [8]
** PLANT AND ANIMAL SPECIES HAVE BEGUN TO SHIFT THEIR TERRITORY
IN RESPONSE TO RISING TEMPERATURES. For example, 45 species of
invertebrates were surveyed along the California coastline in
1930 and again in 1993-94. A definite shift northward in the
range of these species was observed over the 60-year period.
During the period, annual average (mean) ocean temperature at the
shoreline increased 1.35 degrees F. (0.75 degrees C.), and
average summer maximum air temperatures increased 3.9 degrees F.
(2.2 degrees C.). [9]
** In 1994, researchers reported a study of plants on 26 mountain
tops in the Alps in western Austria and eastern Switzerland.
From “12 very precise historical records” the researchers were
able to show that 9 species of plants have been moving upward at
the rate of 4 meters (12 feet) per decade since the original
measurements were made 70 to 90 years ago. [10] These species are
in danger of becoming extinct as they move upward because
eventually they will run out of mountain.
** MOSQUITOES ARE SPREADING: Plants are not the only creatures
moving northward and to higher elevations. Mosquitoes that carry
diseases such as malaria, yellow fever, dengue fever, and
encephalitis are also extending their range, and moving to higher
elevations –thus threatening larger human populations with
exposure to serious infectious diseases. Dengue fever –also
known as “breakbone fever” because it is so painful –appeared in
Texas this past summer.
In May, 1995, researchers in the Netherlands and in England
estimated the increase in malaria that could occur if the IPCC’s
projection for global warming proves correct. They concluded
that, in tropical regions, the “epidemic potential of the
mosquito population” would double; on the other hand, in
temperate climates, the epidemic potential would increase
100-fold (in other words, it would become 100 times as great as
it is today). Furthermore, they said, “There is a real risk of
reintroducing malaria into nonmalarial areas, including parts of
Australia, the United States, and southern Europe.” All told,
they estimated that climate change of 5.4 degrees F. (3 degrees
C.) in the next century could cause an additional 50 million to
80 million new cases of malaria each year around the globe. [11]
Today, about 110 million new cases of malaria occur each year,
globally.
The increase of malaria is not merely theoretical. A recent
study of a 1987 malaria outbreak in Rwanda showed that 80% of the
outbreak could be explained by unusually high temperatures, and
abundant rainfall (both of which are expected to increase with
global warming). [12] A 1.8 degree F. (1.0 degree C.) temperature
increase led to a 337% increase in malaria. Furthermore, there
is evidence of a 5-to-8-year cycle of malaria outbreaks in
various parts of the world, and these can be shown to correlate
with the El Nino Southern Oscillation (ENSO), a periodic warming
of the southern Pacific ocean surface, which usually occurs about
twice each decade. ENSO ordinarily appears at Christmastime and
affects patterns of temperature, rainfall, and drought worldwide
for about a year. [13] Since 1980, ENSO events have occurred more
frequently, and have lasted longer than they used to. As a
writer in SCIENCE magazine said recently, “Recent data suggest
that warming in the deep oceans may be driving El Nino
conditions….” [14]During the period 1991-1994, El Nino recurred
each year –an event without precedent in the historical
record. [15] Paul Epstein of the Harvard School of Public Health
explains the importance of recent El Nino events this way: Warmer
seas evaporate quickly, yielding greater precipitation over some
areas and drought in others. The strength of the 1992/1993 El
Nino was unexpected, and the endurance of +2 to 3 degree C. (3.6
to 5.4 degree F.) increases in ocean temperatures into summer was
unprecedented. As a result of the extended El Nino event of the
last 4 years, weather patterns have become particularly erratic
and volatile (i.e., unstable), Epstein writes.
** ALGAE ARE BLOOMING. Partly as a result of El Nino events,
marine ecosystems around the globe have begun to experience
enormous unnatural blooms of algae. Algae are tiny floating
plants that photosynthesize, which is to say they use energy
from sunlight to combine carbon dioxide and hydrogen (from
water) into carbohydrates. Thus algae form the bottom of the
oceans’ food chains. According to researchers from Harvard
University and from the University of Maryland, recent algae
blooms threaten the health of marine ecosystems,[16,17] and of
humans.
Algae blooms are promoted by many human activities:
** Algae growth is promoted by nitrogen-rich waste waters, by
fertilizers, by acid rain, and by nutrient-carrying soil that
runs off the land when it rains.
** Wetlands and mangroves (“nature’s kidneys”) filter out
nitrates and phosphates (chemicals which act as fertilizers and
promote algae blooms).
** While nutrient sources are increasing, the filtration systems
are being lost to coastal development, to aquaculture (fish
farming), to diking (a response to rising sea levels, caused by
global warming), and to drilling.
** Simultaneously, fish stocks (which eat the creatures that eat
algae) are being depleted (14 of 17 major world fisheries are in
serious decline).
** Simultaneously, climate-related warmer sea-surface
temperatures also increase growth of algae by: (1) increasing
photosynthesis and speeding up the algae’s metabolism; (2)
increasing nutrient-rich coastal upwelling (upward flows of
water); and (3) shifting the community of organisms toward more
toxic species (“red tides,” fish and shellfish poisonings) which
are in turn less palatable to creatures that eat algae.
Why should humans care? For one thing, algae provide a home for
the microbe that causes cholera –an illness that kills humans by
a violent diarrhea, if not promptly and expertly treated. In
1991, El Nino and algae blooms contributed to a massive outbreak
of cholera in Latin America in which 500,000 people fell ill and
5000 died. [16]
In sum, “The spread if infectious diseases will be the most
important public health problem related to climate change,” says
Jonathan Patz, a microbiologist at Johns Hopkins University. [14]
                
                
                
                
    
–Peter Montague
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[1] Svante Arrhenius, “On the Influence of Carbonic Acid in the
Air Upon the Temperature of the Ground,” PHILOSOPHICAL MAGAZINE
(1896) cited in Douglas Cogan, THE GREENHOUSE GAMBIT (Washington,
D.C.: Investor Responsibility Research Center, 1992), pg. 63.
[3] Tim Thwaites, “Are the Antipodes in hot water?” NEW SCIENTIST
November 12, 1994, pg. 21.
Descriptor terms: greenhouse effect; greenhouse gases; carbon
dioxide; air pollution; atmosphere; coal; oil; fossil fuels;
combustion; air temperature; global warming; oceans; glaciers;
mosquitoes; dengue fever; yellow fever; malaria; encephalitis;
rwanda; el nino southern oscillation; enso; paul epstein; algae;
eutrophication; fertilizer; nutrients; mangroves; wetlands;
aquaculture; fish; cholera; infectious diseases;