Carbon Dioxide and Earth's Future Pursuing the ... - Magazooms

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more detail, ultimately concluding that “only very few examples point toward global warming
as a cause of excess viral activity.” Instead, they find that “coupled ocean/atmosphere
circulations and continuous anthropogenic disturbances (increased populations of humans and
domestic animals, socioeconomic instability, armed conflicts, displaced populations,
unbalanced ecosystems, dispersal of resistant pathogens etc.) appear to be the major drivers of
disease variability,” and that global warming “at best” merely “contributes.”
Also exploring this issue about the same time were Gage et al. (2008), who reviewed what was
then known about it; and in doing so, the four researchers -- all of whom hail from the U.S.
Centers for Disease Control’s National Center for Zoonotic, Vector-Borne, and Enteric Diseases -
- concluded that “the precise impacts” of the various climatic changes that are typically claimed
to occur in response to rising atmospheric CO2 concentrations “are difficult to predict.” Indeed,
they say that “in some areas, climate change could increase outbreaks and the spread of some
vector-borne diseases while having quite the opposite effect on other vector-borne diseases.”
In further discussing this complex situation, they also wrote that “the mere establishment of
suitable vectors for a particular agent does not necessarily mean that spread to humans will
commonly occur, as indicated by the limited transmission of dengue and malaria in the
southern U.S.,” because, as they continue, “local transmission has been limited by factors
unrelated to the climatic suitability of the areas for the relevant vector species.” And they add
that “in instances where a vector-borne disease is also zoonotic, the situation is even more
complex, because not only must the vector and pathogen be present, but a competent
vertebrate reservoir host other than humans must also be present.”
So what are some of the non-climatic factors that impact the spread of vector-borne diseases of
humans? Gage et al. list “many other global changes concurrently transforming the world,
including increased economic globalization, the high speed of international travel and transport
of commercial goods, increased population growth, urbanization, civil unrest, displaced refugee
populations, water availability and management, and deforestation and other land-use
changes,” as well, we would add, as the many different ways in which these phenomena are
dealt with by different societies.
Unfortunately, there is almost no way to correctly incorporate such factors into models to
correctly forecast disease incidence in the future. Therefore, in light of the many complex
phenomena that concurrently impact the spread of vector-borne diseases, it is clearly
unjustified to claim that any future warming of the globe will necessarily lead to a net increase
in their global incidence, for just the opposite could well be true, depending on the type and
degree of a number of current and potential societal impacts on the world of nature, as well as
the diverse natures of the evolving states of the planet’s multiple human societies.
Contemporaneously -- and noting that “dengue is a spectrum of disease caused by four
serotypes of the most prevalent arthropod-borne virus affecting humans today,” and that “its
incidence has increased dramatically in the past 50 years,” to where “tens of millions of cases of
dengue fever are estimated to occur annually, including up to 500,000 cases of the life-
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