Why rising temps pose deadlier risk in Nairobi slums

(Credit: Ryan Ryan/Flickr)

The health effects of climate change are likely to be worse in Africa’s crowded urban settlements because temperatures will climb sooner to levels dangerous for children and the elderly.

Residents of these “slum” settlements often experience “micro-climates” warmer even than very close-by urban neighborhoods. The difference is due to home construction materials in the slums, along with lack of ventilation, sparse green cover, and poor access to electric power and other services.

“Our work shows that the health impacts of urbanization and climate change may be hidden from view, particularly in low-income settings,” says Anna Scott, a climate scientist at Johns Hopkins University and lead author of the study in PLOS ONE. “We need more monitoring and data to make sure we can protect everyone’s health in a warming world.”

The study focused on three settlements in Nairobi, Kenya. The largest, Kibera, is a neighborhood of narrow alleyways and homes built of mud walls, iron sheet roofs, and concrete slab floors. Home to as many as a million people, it is the largest of these African neighborhoods, often called “informal settlements.”

High temperatures measured in Kibera and two other nearby neighborhoods were between 5 and nearly 10 degrees Fahrenheit higher than at Nairobi’s nearby official weather station. Researchers say the findings show the need for more targeted heat alerts and assistance.

According to previous research, deaths for children up to 4 years old and people over 50 increased by 1 percent for every nearly 2-degree increase above 68 degrees Fahrenheit.

Extreme heat can be a cause of heat stroke, which can damage the brain and other organs. Heat can also raise the likelihood of death from a heart condition, stroke, or difficulty breathing.

As the Earth warms, the burden of climate change will not fall equally from one part of the planet to another.

The higher temperatures found in the study are “certainly consistent with excess deaths,” Scott says, adding there is not enough information to show how many deaths would result from temperature differences of the magnitude reported in the research, especially as the summer studied for this report was hotter than previous years.

Roughly a third to 60 percent of the 3.1 million people who live in Nairobi, the largest city and capital of Kenya in East Africa, make their homes in settlements such as Kibera, Mukuru, and Mathare, the areas studied for the report.

In Mathare, homes are commonly built with iron walls and roofs. Houses in Mukuru are a mix of some high-rise buildings and houses built of iron sheets. There are few paved streets, trees, or vegetation in any of these areas.

Researchers gathered temperature information over 80 days from December. 2, 2015, to February 20, 2016—a period that turned out to be Nairobi’s hottest summer since the 1970s, which is as far back as available records go.

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Team members posted 50 thermometers on trees and wooden posts in the three settlements, most of them in partial or full shade. They also put one sensor at the University of Nairobi, an area about 7 miles northeast of Kibera that has more trees and green space.

At the end of the 80 days, researchers compared the information gathered in the neighborhoods to temperatures recorded at the Kenya Meteorological Department headquarters, located on a grassy wooded campus less than a half-mile from Kibera.

The results were striking. The average daytime high temperature recorded by the government site for the period was a bit over 25 degrees Celsius, or 78 degrees Fahrenheit. The average was a bit over 82 in Kibera, 85 in Mathare, and 87 in Mukuru.

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The data show that grass and trees help to keep temperatures down, and suggest that as the Earth warms, the burden of climate change will not fall equally from one part of the planet to another.

The impact of heat exposure is a function of both temperature and population, both of which are expected to rise faster in Africa than in Europe. As a result, the burden of climate change is expected to be 100 times greater in Africa.

Other researchers are from the Climate Prediction and Applications Centre, part of the Intergovernmental Authority on Development, based in Nairobi; the University of Nairobi; Virginia Polytechnic Institute and State University; and the American Red Cross, Kenya Red Cross and the Red Cross Red Crescent Climate Centre in the Netherlands. The Red Cross, National Science Foundation and the National Institute of Environmental Health Sciences funded the research.

Source: Johns Hopkins University