OK, OK, man-made global warming is real and it might pose some problems for humanity, but one of the most overhyped "problems" is the claim that GW will drive "tropical" diseases into temperate zones. One such over-the-top article "Climate Change Drives Disease To New Territory" appears in today's Washington Post. The article portentuously declares:
Global warming—with an accompanying rise in floods and droughts—is fueling the spread of epidemics in areas unprepared for the diseases, say many health experts worldwide. Mosquitoes, ticks, mice and other carriers are surviving warmer winters and expanding their range, bringing health threats with them.
Let's take a look at the diseases listed by the Post article that we in the United States will soon allegedly enjoy thanks for rising temperatures.
Malaria–This mosquito-borne parasite was probably first brought to the Americas 500 years ago by Spanish explorers. Historically, malaria outbreaks occurred as far north as Sweden and Finland. Malaria was endemic to most of the United States until the 20th century and it wasn't eradiated until 1950 in the southern U.S. when disease-carrying mosquitoes were controlled by the application of DDT. Fun fact: During the Civil War, one half of the white troops and 80 percent of the black soldiers of the Union Army got malaria annually. If malaria becomes epidemic in the United States again that will signal far worse public health problems than an increase in average global temperatures. And if malaria is still infecting 600 million people per year by 2100 that will mean that human ingenuity has failed to increase wealth for the poorest of the world's people, improve mosquito control and develop an effective vaccine.
Cholera–This water and food-borne bacterial disease arose in India during the early 1800s and spread along the world's trading routes very quickly. Outbreaks in New York in 1832 and 1848 killed thousands and periodic epidemics spread nationwide. It was defeated by creation of sanitary water supplies and sewage disposal. The disease returned to the Americas in 1991 apparently when a cargo ship dumped its contaminated bilge into the harbor at Lima, Peru. It spread rapidly because Peruvian public health authorities had stopped chlorinating public water supplies. Again, if the disease becomes epidemic again in the U.S., higher temperatures will not be the cause and will be the least of our worries.
Dengue Fever–This mosquito-borne viral disease apparently began in Africa and was spread by the slave trade. The first outbreak was recorded in Indonesia in 1779 and an outbreak occurred in Philadelphia a year later. The disease remained endemic in a swath across U.S. southern states until this century. Mosquito control finally eliminated it.
Lyme Disease–This tick-borne bacterial disease was first found in Lyme, Connecticut. The Centers for Disease Control believe that its spread is the result of reforestation around suburban communities that created the perfect habitat for burgeoning herds of deer and coincidentally deer ticks which carry the disease. White tail deer range throughout most of the United States. A few years back I actually got the characteristic Lyme bull's eye rash from a tick that I apparently picked up while working around my cabin. I took antibiotics and am fine. We await the development of a truly effective vaccine.
West Nile Virus–This mosquito-borne virus first appeared in New York City in 1999, apparently somehow arriving from Israel. It is quickly spreading across the country carried by birds on which mosquitoes feast. The Centers for Disease Control map of WNV and related viruses shows that WNV is not confined to tropical regions. WNV took hold here not because of increases in global temperatures, but because, like malaria, cholera, and dengue before it, an appropriate carrier finally made it across the Atlantic. Like all of the other diseases discussed by the Washington Post, lowering temperatures is not the way they will be controlled, effective vaccines is.
It is true that at the margin higher average temperatures may help some diseases and their vectors to spread a bit, but with regard to controlling infectious diseases we've got much bigger problems than that. The fact is we already know how to control diseases no matter what the climate is–better vector control and the development of effective vaccines. Focusing on anything else is just another exaggerated environmentalist scare story.