December 16, 1998
Earl Pratt
Kelli Dennis
Jeremy Rentz
Presented to:
Dr. Carmichael
Department of Chemical and Biochemical Engineering
The University of Iowa
Iowa City, Ia 52246
Introduction
of global climate change
Land mass losses
Increased disease rates
Direct-Weather Related Mortality
Bibliography
Introduction
of global climate change
Human health, natural ecological sysems,
and socioeconomic systems are all sensitive to both the magnitude and the
rate of climate change. Many physical and ecological systems will
be affected simultaneously. The ability of these natural ecological
systems to migrate appears to much slower then the pedicted rate of climate
change. Climate change can add to existing environmental stresses.
Land
mass losses
Due to global warming, the sea
level is rising. It is rising more rapidly in the U.S. than compared
to anywhere else in the world. Studies by EPA have estimated that
the Gulf and the Atlantic coasts will raise one foot in sea level by approximately
2050. It is also estimated to raise two to four feet in the next
century.
The effects of rising sea level will erode wetlands and beaches.
New wetlands will form as the sea level rises, by flooding dry land, and
the existing wetlands will erode if the seal level rises a few feet.
The newly created wetlands will be a small area compared to the area destroyed
due to this sea level rise. Nationwide, a two-foot rise in sea level
could eliminate 17-43 percent of US wetlands. Nationwide, about 5000
square miles of dry land are within two feet of high tide. All of this
land would be destroyed by rising sea level. Additional dikes and
bulkheads need to be constructed to protect this area of land. A two-foot
rise in sea level will eliminate around 10,000 square miles of land.
This land eliminated includes both the wetlands and dry land that would
be lost to the sea. This reduction of landmass will increase population
density. A more populated area will initiate a more rapid spread
of disease.
Increased
disease rates
An increase in the rates of mosquito
carried diseases like malaria and dengue fever has occurred in the last
twenty years. These diseases are known as vector-born diseases because
the mosquito is utilized for a portion the life cycle of the parasite.
Health research in the last century has shown that climate will describe
the distribution of mosquito-borne diseases. Localized weather patterns
have also been shown to affect the timing and the intensity of such disease
outbreaks. For this reason, discussions into how global climate change
will alter the rates and distribution of these vector-borne diseases will
be discussed here along with other possible health effects.
It has been estimated that 1 in
20 people in the world are infected with one form of malaria or another.
These infection rates correspond to approxiamately 2 million deaths world
wide, including about 1 million deaths of young children. Malaria
arises from 4 species of the plasmodium parasite. The most dangerous
of these paraisites is Plasmodium falciparum and the most widely
distributed parasite is P. vivax. Anopheline spp.and Aedes
aegyptii mosquitoes are two of the vectors used by the plasmodium to
transmit malaria.
Anopheline spp. 
Aedes aegyptii
As global temperatures increase, several factors affect the
distribution and severity of malaria infection rates. As winter temperatures
rise in Northern lattitudes, mosquitoes will be able to survive in shelters
more readily than in previous years. Most of the malaria vectors
will survive at temperatures above 22 degrees Celsius (McMicael, A.J.).
Survival rates in temperate zones are anticipated to increase with Global
warming. The Plasmodium parasites are also sensitive to temperature
changes. The sensitivity is shown in the sexual developement of the
particular species. Incubation of the plasmodium does not occur outside
of a 14 - 38 degrees Celsius temperature range (McMicael, A.J.).
The optimum incubation temperature varies between 25 degrees Celsius for
P. vivax, to 30 degrees Celsius for P. falciparum, and 22
degrees Celsius for P. malariae. Locally, a slight increase
in the minmum night time temperature in the 14 - 18 degrees Celsius range
will greatly increase the incubation rate of the plasmodium parasites.
Global climate changes also include precipitation changes. The majority
of the forcasted precipitaton increases will come in the form of increased
large storms and an overall increase in global precipitation. These
large storms coupled with more precipitation in various areas of the world
will increase the breeding of vectors. Ironically, as areas of drought
will also occur, more puddles will form that are the ideal conditons for
vector breeding causing localized epidemics from puddle breeding.
Global climate changes will also affect the distribution
and span of malaria cases. As temperatures increase, the mosquitoes
will be able to survive at higher and higher altitudes. The increase
in altitude will be the major migration of increased malaria rates.
The above graphic shows increases in parasite indexes from 1960 to 1995
for South America. It must be noted that malaria rates had been very
low in the 50's and 60's with the advent of vaccines and an educated public.
However, the increases in relative parasite numbers results from more resistant
strains and newer localized species.
Direct-Weather
Related Mortality
The easiest adverse affect to predict from global
warming is heat stress. Heat places stress on the thermoregulatory
system, which affects the circulatory system. In individuals whose
circulatory systems are already compromised (for example: the elderly,
the sick, or the very young) additional stress brought about by increased
temperatures can be extremely unfavorable, and may result in death.
According to http://www.ciesin.org/TG/HH/mortmech.html,
a test was conducted to the potential impact of global warming on heat
stress related mortality in 15 cities across the United States. The
conclusion was that the rate was dependent on the rate of acclimatization.
In the Southern United States mortality rate was not expected to rise considerably
due to heat stress because their populations are acclimatized to hot weather.
The Northern United States would show an increase in summer heat related
deaths in 15 cities. This is taking into account that the number
of cold-related deaths would probably drop. The EPA has reported to Congress
that we might expect a sevenfold increase in heat-related deaths by the
middle of the 21st century if acclimatization does not occur.
This would render heat-related deaths as a major killer, rivaling the present
number of deaths from leukemia.
Bibliography:
McMichael, A.J., Haines, Sloof, Kovats, Climate Change
and Human Health, World Health Organization, 1996, pages 78-86.
Roberts, Donald R., Laughlin, Hsheih, Legters, "DDT, Global
Strategies, and a Malaria Control Crisis is South America", Emerging
Infectious Diseases, Vol. 3, No. 3, July-September 1997.
Epstein, Paul R., Et. al, "Biological and Physical Signs
of Climate Change: Focus on Mosquito-borne Diseases", Bulletin of the
American Meteorological Society, Vol. 79, No. 3, March 1998,
pages 409-415.
http://www.epa.gov/globalwarming/
