Site icon Conservation news

From theory to deadly reality: malaria moving upslope due to global warming

Malaria is a global scourge: despite centuries of efforts to combat the mosquito-borne disease, it still kills between 660,000 to 1.2 million people a year, according to World Health Organization data from 2010. Astoundingly, experts estimate that around 300 million people are infected with the disease every year or about 4 percent of the world’s total population. And these stats may only get worse. For years scientists have vigorously debated whether or not malaria will expand as global warming worsens, but a new study in Science lays down the first hard evidence.



“We saw an upward expansion of malaria cases to higher altitudes in warmer years, which is a clear signal of a response by highland malaria to changes in climate,” said co-author Mercedes Pascual with the University of Michigan.



The researchers looked at malaria prevalence in two highland regions in Ethiopia and Colombia over more than a decade. In the past, tropical highlands have been largely safe from malaria outbreaks because of mosquitoes’ inability to handle the cooler climate.



“Colder temperatures at higher altitude in these tropical latitudes slow down and even halt the development of the parasite inside the mosquito vector, decrease the rate of reproduction, and reduce the biting rate of the vector, minimizing, if not preventing, transmission,” the scientists write in the paper released today.



However, during abnormally warm years—the number of which are rising due to climate change—the researchers found that malarial mosquitoes moved into these normally inhospitable, and unprepared, regions.





An Anopheles gambiae mosquito, which transmits malaria in the Ethiopian highlands. Photo by: Dan Salaman, London School of Hygiene & Tropical Medicine.



“Malaria cases occurred at higher elevations in warmer years, notably in 1997 and 2002, in both regions,” the scientists write. “This synchrony between continents may be related to above-normal global temperatures that accompany El Niño events.”



The researchers’ findings strike at the heart of an ongoing argument over whether or not malaria expand spread as temperatures rose, and the extent of the impact. In order to isolate their findings, the scientists took into account other factors such as rainfall, insecticide use, and resistance to anti-malarial drugs. Importantly, in both the Ethiopia and Colombia, temperature proved the best explanation for outbreaks.



“Our latest research suggests that with progressive global warming, malaria will creep up the mountains and spread to new high-altitude areas. And because these populations lack protective immunity, they will be particularly vulnerable for severe morbidity and mortality,” noted co-author Menno Bouma an Honorary Senior Clinical Lecturer at the London School of Hygiene & Tropical Medicine. Experts have long warned that climate change is likely to hit the world’s poorest and most marginalized (and those least responsible) hardest. These new findings add greater weight to this argument.



The implications could be profound: Ethiopia’s highlands, alone, contain 37 million people living in rural areas. In fact, the scientists estimate that just one degree (Celsius) of warming could lead to an additional 2.8 million infections among children in the country’s highlands. Already, the global climate has warmed 0.8 degrees Celsius and while governments have pledged to tackle global climate change their current target is a 2 degree Celsius rise (and they are barely making headway to this mark).



“Our findings here underscore the size of the problem and emphasize the need for sustained intervention efforts in these regions, especially in Africa,” said Pascual.



Highland communities need not be victims, however. After suffering a malaria epidemic between 2002-2004, communities in the Ethiopian highlands responded with stepped-up insecticide use and better anti-malarial medicine. This lead to a “considerable reduction of cases” according to the authors. But this will require increased public health efforts in these regions, say the scientists.



In addition to moving into higher altitudes, scientists have also predicted that in a warmer world malaria will likely seep north and south, invading new latitudes and perhaps returning to countries where it was long evicted. Two years ago avian malaria—similar to human malaria—was found in birds as far north as Alaska. Meanwhile, scientists are working furiously to develop a malaria vaccine or other means—including genetic manipulation in mosquito populations—to stop the disease cold.




A highlands region in Ethiopia. Photo by: Asnakew Yeshiwondim.











Related articles


Despite frigid cold in U.S., January was the fourth warmest on record worldwide

(02/27/2014) Worldwide, this January was the fourth warmest since record-keeping began, according to new data released by National Oceanic and Atmospheric Administration (NOAA). While parts of the world, most notably eastern North America and northern Russia, experienced temperatures well-below average, overall the month was a scorcher. In fact, another dataset, from NASA’s Goddard Institute for Space Studies (GISS), that uses different methodology, found that January was the third warmest since record keeping began.

Ocean acidifying 10 times faster than anytime in the last 55 million years, putting polar ecosystems at risk

(02/24/2014) An assessment of ocean acidification, presented at the UN Climate Change Conference in Warsaw in November 2013, starkly concluded that acidity is on track to rise 170 percent by the end of this century. As many key species are sensitive to changes in acidity, this would drastically impact ocean ecosystems, with effects especially pronounced in polar regions where the cold waters intensify acidification, and which are home to many organisms that are particularly vulnerable to acidification.

Alaska roasting: new NASA map shows the Final Frontier in grip of January heatwave

(02/05/2014) Alaska got California weather at the end of January, as displayed by a new map based on data by NASA’s Terra satellite’s Moderate Resolution Imaging Spectroradiometer (MODIS). The U.S. state experiences one of its warmest winter periods on record during the second half of January, including some temperatures that ran 40 degrees Fahrenheit (22 degrees Celsius) above average. According to the EPA, temperatures in Alaska have risen an average of 3.4 degrees Fahrenheit (1.9 degrees Celsius) in just the last 50 years due to climate change.

2013 was the seventh hottest year yet

(01/27/2014) Global warming continues apace as 2013 was the seventh warmest year in the past 133 years, according to a new analysis from NASA’s Goddard Institute for Space Studies (GISS). In total, the global temperature in 2013 averaged 14.6 degrees Celsius (58.3 degrees Fahrenheit), or 0.6 degrees Celsius (1.1 degrees Fahrenheit) hotter than the 20th Century average.

Underestimating global warming: gaps in Arctic temperature data lead scientists and public astray

(01/15/2014) No place on Earth is heating up faster than the Arctic, but just how fast has remained an open question due to large gaps in temperature data across the vast region. Now, a recent study in the Quarterly Journal of the Royal Meteorological Society finds that not only is the Arctic warming eight times faster than the rest of the planet, but failure to account for temperature gaps has led global datasets to underestimate the rise of temperatures worldwide.

Carbon emissions rise 2 percent in U.S. due to increase in coal

(01/14/2014) Carbon dioxide emissions rose two percent in the U.S. last year, according to preliminary data from the Energy Information Administration. Emissions rose largely due to increased coal consumption, the first such rise in U.S. emissions since 2010. Still, the annual emissions remain well below the peak hit in 2007 when emissions hit 6 billion tons.

Climate fail: Geoengineering would cool planet, but screw up rainfall patterns

(01/14/2014) For decades, scientists have been grappling with the consequences of climate change and working toward viable solutions. Climate engineering, also known as geoengineering, is the most controversial possible solution. Currently, one of the most talked about geoengineering ideas is Solar Radiation Management (SRM), which intends to block shortwave solar radiation, thus cooling the Earth to offset rising temperatures. In other words, SRM may be one way in which global temperatures could be artificially stabilized.

Down Under scorching: Australia experiences warmest year on record

(01/06/2014) Australia had its warmest year on record, with annual temperatures 1.2 degrees Celsius (2.16 degrees Fahrenheit) above the 1961-1990 average, according to a new analysis from Australia’s Bureau of Meteorology (BOM). This is 0.5 degrees Celsius higher than the previous warmest year on record—2005—for Australia. Global warming due to burning fossil fuels is increasing temperatures worldwide.

Global warming could upset Antarctic food chain

(01/02/2014) Resting near the bottom of the foodchain, Antarctic krill (Euphausia superba) underpin much of the Southern Ocean’s ecosystem. But in a rapidly warming world, these hugely-abundant crustaceans could see their habitat shrink considerably. In a recent paper in PLOS ONE, scientists predict that Antarctic krill could lose 20 percent of their growth habitat, or 1.2 million square kilometers.