13 September 2007

Disease and climate change

Throughout history, disease has played a major role in human affairs. From The Fourth Horseman by A. Nikiforuk:

...[E]pidemics have crumbled empires, defeated armies and forever changed the way we live and love. Smallpox conquered the New World...Plague defeated feudalism [and] fertilized the seeds of capitalism...Malaria extended the viability of the slave trade...the Fourth Horseman rides into our lives at his convenience. (Page xv of introduction)

Our current experiments in environmental modification – greenhouse gas enhancement, land use changes and the like – are saddling up his steed for yet another foray through our overpopulated world. The signs are already appearing, as evidenced by the following recent news items

  • The central highlands region of Kenya, previously malaria-free, is experiencing widespread outbreaks of the disease as mosquitoes expand their range due to rising temperatures associated with global warming. [item]
  • Leishmaniasis, a flesh-eating and sometimes fatal disease will become more prevalent as the climate warms. The sand fly whose bite transmits the parasitic infection is typically only found in the tropics. As temperatures rise, it is able to colonize and broader range and transmit the disease. [item]
  • Global climate change has for several years been contributing greatly to the spread of cholera through associated increase in the frequency of torrential rain, floods and periods of drought. [item]
  • A suggestion that climatic change will render conditions more favorable for human plague, which is still reported regularly in Central Asia. [item]
  • Legionnaire's disease is on the rise in the UK. Last year, the number of cases was the highest ever reported. The the limited evidence available indicates that the increase could be the result of climate change. [item]

Deadly new diseases also emerge regularly, due in part to “...[e]xplosive population growth, intensive agricultural practices, and changes in sexual behavior”.Relatively recent emergees include Ebola -- a new outbreak of which is being reported in the Congo, and bird flu, for which first documented case of human-to-human transmission has been reported in Indonesia. Whatever relationship, if any, these diseases have to climate change is unknown. But as the WHO report linked above indicates, human activities are the source of these maladies.

The spectre of human-induced pandemic, wither through climate or other sources, serves as another wake-up call to humanity. It is time to change our ways. We need to reduce our heedless exploitation of the planet, sensibly reduce the population (how?) and assist those in need in order to prevent future calamity. It is a difficult task, and no-one knows all the answers. The most arduous journey begins with a few small steps. We need to take those steps now.

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