Public-health efforts and increasing urbanization have overwhelmed any effects that global warming has had on malaria, according to a new analysis.
Malaria may not deserve its high-profile spot as a leading public-health concern tied to global warming.
A research team has found that over the past century, malaria's prevalence has declined significantly, despite a century-long warming of global average temperatures.
The finding was published in this week's issue of the journal Nature by the Malaria Atlas Project, an international consortium of researchers that maps and tracks incidence of the disease, as well as social and environmental factors.
Warming can stimulate malaria outbreaks, as can increased rainfall and even drought, notes David Smith, an associate professor of zoology and an associate director of the Emerging Pathogens Institute at the University of Florida in Gainesville.
But the analysis holds that public-health efforts – from the expanded use of insecticide-laced mosquito nets around beds to improved treatments – and increasing urbanization have overwhelmed any climate-related effect on the incidence of the disease.
"We're not saying that weather and climate won't affect malaria," Dr. Smith writes in an e-mail exchange. "But we are arguing that there are much more powerful forces at work. The broad patterns of the last century suggest an optimistic picture for malaria."
The team compared a map it developed in 2007 showing the prevalence of malaria globally with maps based on historical data dating back to 1900, when malaria is widely considered to have peaked.
Despite the increase in global average temperatures, the prevalence of malaria fell globally. According to the team's estimates, some 58 percent of the globe's landscape was malaria prone in 1900, versus 30 percent in 2007.
Those numbers may be of little comfort to people who public-health officials say are still at risk, acknowledges Pete Gething, a researcher at Oxford University in England and leader of the team reporting the results. But the trend "is important when thinking about the effects of climate on the future of disease," he says.