- Extreme heat costs tropical countries more than 5% of their annual per capita GDP, new research shows, while more prosperous mid-latitude countries lose only about a 1% of GDP due to heat waves, which can even bolster economic growth in some instances.
- Poorer tropical countries suffer the worst effects of heat waves despite being least culpable and least economically capable of adapting.
- The effects of extreme heat and drought can hit hard in local communities, such as among Kenyan families who rely on cattle they can no longer feed.
BISSIL, Kenya — Heat waves are on the rise globally, and countries least culpable suffer the worst effects. While temperatures continue to rise worldwide, new research published in the journal Science Advances shows that poor tropical countries bear the greatest economic brunt of increases in extreme heat, which decreases economic growth in regions where local economies are least able to adapt.
The last eight years were the warmest ever recorded. This has resulted in an increase in extreme weather events, including heat waves, floods and drought.
According to the research in Science Advances, titled “Globally unequal effect of extreme heat on economic growth,” the extreme temperatures witnessed are a result of human activities that emit excess carbon into the atmosphere. A vast extent of the emissions come from rich countries, which makes them primarily responsible for increases in global temperatures. Yet, the study shows, rich countries’ economies are least affected. In fact, the researchers find, extreme heat can actually increase economic growth in cold regions.
“Places that are harmed most by heat waves in our data are disproportionately warm places, across the tropics [that] are also lower-income and also lower-emitting, and so you have this pattern where the people that have contributed least to climate change are the most vulnerable to it, and also where these heat waves are hitting them the hardest,” says Christopher Callahan, the lead author of the paper.
Extreme temperatures take a heavy toll on the economic performance of tropical low-income countries. Based on the sampled regions, the research points out that in tropical countries, the per capita gross domestic product (GDP), which is the measure of a country’s economic output per person, is more than 5% lower than it would have been without heat waves. On the other hand, heat waves affect the per capita GDP of mid-latitude countries by a decrease of only about 1%. Callahan explains that this is a result of the already warm temperatures in tropical regions, which are worsened by heat waves.
“Additional heat is very dangerous because you might already be very close, for example, to the threshold where crops start to die; and since you are already close to that threshold, it just takes a little bit of heat …[to] kill crops and make people sick.”
According to the research, a conservative estimate of global losses accrued from extreme heat totaled at least $16 trillion in 2013. For perspective, that’s the equivalent of a tropical country like Kenya’s entire annual budget for more than 580 years (if it were to stay constant). More liberal estimates project losses of roughly $65 trillion or more globally.
Kenya provides an example of the researchers’ findings as a lower-middle-income tropical country that faces disproportionate effects of climate change. Joyce Kimutai, a principal meteorologist at the Kenya Meteorological Department and PhD student at the African Climate & Development Initiative in Cape Town, says that extreme heat and an ongoing drought in Kenya are correlated. Kenya is currently suffering a drought said to be the worst in the country’s history, with a reported 5.1 million Kenyans facing starvation.
“When droughts occur, you find that it is accompanied by elevated temperatures as well, so we call them compounding events,” she says, adding that heat waves can occur either as a result of droughts or concurrently with them.
Despite the absence of heat wave records in both national and international databases for Kenya, research shows the country has experienced heat waves ranging from “normal” to “deadly,” lasting between 3 and 26 days. This research, based on data collected between 1987 and 2016, also finds that heat waves have worsened in recent years, with the most extreme recorded in 2015. The worst-affected areas are eastern and northern parts of Kenya, which are also currently most affected by drought.
The economic implication of this is enormous, with the Kenyan government reporting it has needed 17 billion shillings ($138.5 million) between November 2022 and January 2023 to fight the worsening drought.
Christine Maswi, a principal meteorologist at the Kenya Meteorological Department, says that heat waves affect humans and animals alike. While humans may get sicker or wane in productivity, animals can very easily die — not just from lack of feed and water, but from heat stress as well.
“One of the effects of the heat waves is heat stress [in the animals] … which could lead to death,” Maswi says. She adds that degradation of pasture and water sources makes things worse.
A report published by Kenya’s Wildlife Research and Training Institute highlighted 1,198 wildlife mortalities — including wildebeest, plains zebra (also known as common zebra, Equus quagga) and Grévy’s zebra (Equus grevyi), elephants and buffalo — attributed to drought between February and October 2022 due to lack of water and feed.
Mutunkei Parmet knows too well what it means to have one’s livelihood hang in the balance owing to extreme temperatures and drought. Parmet, a resident of Bisil in Kajiado county in Kenya’s Rift Valley, earns a living from buying and selling cows. He recounts how he and his family have suffered the pangs of drought over the last few months. According to the National Drought Management Authority (NDMA) December 2022 drought updates, Kajiado is among the worst-hit counties listed in the alarm drought phase. NDMA is a government agency that monitors droughts and coordinates responses.
“For over the last year now, cattle have totally lost value,” Parmet says. “Normally, we sell cattle between 20,000-100,000 kenyan shillings [$163 – $816] but now the highest price we sell is 15,000 shillings [$122].”
Parmet adds that due to lack of water and pasture, he and his family have been forced to sell their cattle at a “throw-away price,” for as low as 1,000 shillings ($8.16) for a fully grown cow. Parmet, who has six children between the ages of 1 and 13 years, has lost 48 cows in a span of 7 months, leaving him with only two.
Dire need forces his family to sell the cows, no matter how small the price, Parmet says. At least the family gets something that way. During these hard times, they “lack food for the children, let alone the cows,” he says. “If you get 1,000 shillings [$8], the children get something to eat. If the cow dies at home, it’s a huge loss — and you do not get food for that day.”
The clear connection between droughts and heat waves highlights how one problem is compounded by the other. Parmet says that the hot sun seems too eager to make an already bad situation worse.
Kimutai acknowledges that extreme heat during drought, though common, exacerbates the situation. “I did a study in Kenya in 2016; as much as we could see the signal of climate change in drought, we [also] saw the signal in extreme heat; we saw a shift in temperatures so for sure the elevated temperatures that we see currently are attributable to climate change,” says Kimutai.
These shifts also affect human health. Kimutai, whose focus is on weather extremes, has co-authored a paper on the effects of extreme heat on human physiology. The paper, which is still under review, establishes a correlation between heat waves and elevated cases of hospitalizations and admissions in the cities of Mombasa, Nairobi and Kisumu.
“It seems that when temperatures are a bit elevated, people’s conditions are exacerbated, so when you go to the hospital you are likely to be bedridden, or when you are in the hospital you are likely to stay there longer or people with preexisting conditions are likely to visit the hospital and get admitted,” Kimutai says.
Research shows that the added costs of treatment for heat-related illnesses combine with decreased productivity, effects on crops and food supplies and other factors that add to the overall economic toll of extreme heat.
According to Callahan, adaptation to extreme heat depends on income. He says this impedes technologically driven adaptation measures such as installation of air conditioning, since the worst-affected regions also happen to be low-income regions.
“One of the key things that is going to be necessary everywhere in the world is air conditioning,” he says. “Unfortunately, air conditioning is very expensive and so the ability to adapt to climate change currently is structured by income.”
He adds that in higher-income countries, in addition to infrastructural changes like air conditioning, adaptation usually entails structural economic shifts from agriculturally focused to service sector focused economies. On the other hand, in lower-income countries, adaptations are behavioral. For instance: moving indoors during the hottest part of the day or doing labor-intensive jobs in the mornings and evenings when temperatures are cooler. These may not be effective most times.
However, Callahan adds that planting trees could go a long way to help communities adapt to extreme heat. This could be one of the most effective strategies to help alleviate the problem in Kenya with the government committing to increase the country’s tree cover from 12% to 30% by 2032.
“Green spaces are an underrated climate adaptation. … The availability of trees and green spaces can radically change city environments; trees provide shade, they transpire water into the atmosphere and the water in the air can cool the air, and they provide an open space away from buildings,” Callahan says.
While the scope of his team’s research is limited to GDP, Callahan says the effects of heat waves go beyond that, and it may not be possible to fully estimate all losses.
“You have an economy that produces goods and services [that] get wrapped into this label of gross domestic product,” he says. “The problem with this is that GDP, monetary and economic outputs … things that we put dollars on, is a very incomplete assessment of what matters to us. And so one category of some of the most severe impacts of climate change are going to be: species loss, biodiversity loss [and] habitat loss.”
He says that increased adaptation measures have to be coupled with emissions reduction alongside the possibility of compensation for loss and damage by the high-emitting countries. At the close of COP27 in Egypt, delegates agreed to establish a fund to compensate poorer countries for losses attributed to climate change.
“Large emitters need to pay smaller emitters … for losses they have suffered [and] our research makes it very clear that those losses are very large and need to be compensated,” Callahan says.
He says extreme heat is not getting any better, and extreme measures are imperative. The economic implications projected by the research, aside from highlighting the great extent of losses from extreme heat, should serve as a wake-up call that something needs to be done urgently, he says.
Callahan, C. W., & Mankin, J. S. (2022). Globally unequal effect of extreme heat on economic growth. Science Advances, 8(43). doi:10.1126/sciadv.add3726
Human Rights Watch. (2014). “There is No Time Left”: Climate Change, Environmental Threats, and Human Rights in Turkana County, Kenya. Retrieved from https://www.hrw.org/sites/default/files/report_pdf/kenya1015_brochure_web.pdf
Amou, M., Gyilbag, A., Demelash, T., & Xu, Y. (2020). Heatwaves in Kenya 1987–2016: Facts from CHIRTS high resolution satellite remotely sensed and station blended temperature dataset. Atmosphere, 12(1), 37. doi:10.3390/atmos12010037
The Impacts of the Current Drought on Wildlife in Kenya. (2022). Retrieved from Wildlife Research and Training Institute website: https://www.scribd.com/document/609219507/48-WRTI-Drought-Report-2022-Final-Nov-2nd#