Scientists are warning that climate change — warmer temperatures, specifically — are letting mosquitoes that carry malaria flourish in places they normally haven’t. And that means malaria, which relies on the winged beasts, could also flourish in places not previously seen.
As The Washington Post couched it, “As temperatures rise, many tropical species once confined to the warmest parts of the globe are expected to climb to higher altitudes and creep farther from the equator.”
In a news release this week for a study published in the journal Biology Letters, researchers at Georgetown University warned that “mosquitoes responsible for transmitting malaria in Africa are spreading deeper into southern Africa and to higher elevations than previously recorded.”
Biology Letters is a peer-reviewed journal produced by The Royal Society Publishing. The scientists noted they used “one of the most comprehensive datasets ever compiled by medical entomologists to track the observed range limits of African malaria mosquito vectors (Anopheles spp.) from 1898 to 2016.”
“This is exactly what we would expect to see if climate change is helping these species reach colder parts of the continent,” Colin Carlson, who has a doctorate and is an assistant research professor at the Center for Global Health Science and Security at Georgetown, who led the study, said. “If mosquitoes are spreading into these areas for the first time, it might help explain some recent changes in malaria transmission that have otherwise been hard to trace back to climate.”
“As the planet warms, plants and animals — particularly invertebrates — are seeking cooler temperatures, either by moving to higher altitudes or by moving closer to the poles,” The New York Times reported. “Ticks that transmit Lyme disease, for example, are dramatically expanding their range in the northern United States. Bats are also on the move, and with them diseases that they transmit, such as rabies.”
Carlson told The Washington Post that more data is needed to directly connect warming temperatures to spread of malaria mosquitoes. “But what we can say is a lot of these species are moving in the direction and at the speed that looks like a climate change impact.”
The researchers noted, too, that back in 2011 “scientists estimated that earthbound species were moving uphill at a rate of 1.1 meters a year, and to polar latitudes at 1.7 kilometers per year.”
In contrast, the new study showed that the Anopheles mosquitoes in sub-Saharan Africa gained roughly 21 feet a year and expanded their range south of the equator by nearly three miles a year.
They were able to consider the spread of malaria because those mosquitoes spread the disease and have been tracked historically for decades. The release said other species “are probably moving in similar ways,” but more region-specific, disease-specific and species-specific study is needed.
The Times noted that mosquitoes reproduce more often at higher temperatures.