Some effects of climate change are direct and fairly obvious: higher temperatures in the winter; warmer temperatures at higher elevations; higher sea levels (though this varies from region to region, as recent research has discovered); acidification of the ocean as excess CO2 piles up in the atmosphere since geologic processes can’t operate on the timescale that humans can. Some effects will come about as a result of two or more other effects combining: movement of ecosystems poleward and higher in elevation; extinction of species since they can’t evolve on the timescale that humans are forcing the climate.
One of those complex effects that aren’t obvious in model output data, for example, is the future spread of disease. With warmer temperatures and more water vapor in places that were more moderate in their pre-21st century climate, new diseases will become something to watch for. One of those diseases will be dengue fever. If you haven’t heard of that, you’re not alone. Dengue fever is a viral, tropical disease vectored to humans by mosquitoes. Symptoms include severe headaches, muscle and joint pain, fever and rash. Left untreated, it kills its host.
2.5 billion people are currently at risk from the disease. As more U.S. states continue to see yearly average temperatures increase, mosquitoes carrying the disease will spread further into the country. What was a disease of poorer countries closer to the Equator will begin to affect richer countries. Oh, don’t think for an instant that the effect will be seen across all demographic lines here in the U.S. As with most other diseases, dengue fever is more likely to affect poorer Americans.