According to the ecologist, the malaria parasite is highly sensitive to changes in temperature. Even subtle warming can dramatically increase populations of the mosquitoes that transmit the disease.
Some scientists have argued that climate is not involved in the increasing highland epidemics. Instead,
they say, adaptations in the parasite that make it resistant to anti-malarial drugs are the key drivers.

But Pascual says that this “either-or” view is misguided and improperly lets global warming off the hook. More likely, Pascual says, the two work in tandem to an effect greater than the sum of their parts, with rising temperatures leading to faster development of drug resistance.

“The literature has this controversy of 'Is it climate or is it drug resistance?' and drug resistance is taken as evidence that we don't need to invoke climate change,” she adds.

No research has shown this synergy, but Pascual says it makes theoretical sense.
By making conditions favourable for mosquitoes, “warmer temperatures increase transmission, so you're going to increase the number of people you treat,” she says.  And past research has shown a threshold at which treating more cases leads to a higher incidence of drug resistance, making the disease difficult to treat and contain.
Malaria kills 3,000 people each day in Africa, and outbreaks on the continent are not limited to the
eastern highlands. Climate change will cause the disease to migrate away from low latitudes, according to scientists. That could rid some areas of outbreaks but could cause others in regions whose inhabitants have not developed any immunity.

The specifics of how malaria's climate-forced migration will affect outbreaks are largely unknown, but it is already underway, says Christopher Thomas of Aberystwyth University in the United Kingdom.