Climate zones in Kenya are shifting toward hotter and drier conditions, a new study looking at how temperature and precipitation trends have changed over time and how the geographic distribution and arrangement of climate zones in Kenya shifted due to those trends has established.

“In the past 40 years arid climate regions in Kenya have expanded from 72 to 81 percent, a roughly 50,000-km2 shift from humid and semi-humid-to-semi-arid to arid regions. While tropical climate regions expanded from 91 to 93 percent with over 13,000km2 shifting from high-altitude and temperate regions to tropical ones,” say the research team that analysed Kenya’s geographic distribution and arrangement of climate zones between 1980 and 2020.

“We observed an approximate 1°C increase in average annual temperature since the 1970s,” said the team.

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Agricultural casualty

Overall, more than 36 percent of all of Kenya’s area experienced either shifts in precipitation zones only, shifts in temperature zones only, or shifts in both temperature and precipitation zones. Furthermore, all arid regions expanded from 72 percent over all of Kenya’s area in 1980 to 81 percent in 2020. The hottest zone increased 0.59°C.

A woman drives her livestock along a dry bend of River Nyariginu in Laikipia County, Kenya, in search of water on February 16, 2023. PHOTO | JOSEPH KANYI | NMG

The study titled Shifting Climate Zones and Expanding Tropical and Arid Climate Regions Across Kenya (1980-2020) and published online on April 5, says these shifts will cause ecological diversity to decline, posing a major threat to ecosystems with far-reaching social and ecological impacts.

One of the significant implications is expected in agricultural land use and ecosystem management. “These shifts will pose a serious threat to agricultural systems, crop yields, agricultural activities, and food prices,” it said.

“Increasing temperature and changes to temperature zones likely exacerbate the expansion of drylands in Kenya. Specifically, drylands in arid regions are expected to dry more quickly and severely and to a greater extent than in humid regions. Tropical – fairly hot to very hot, which comprises a large majority of Kenya, expanded substantially more than any other temperature zone. The enhanced warming has important implications in interpreting global warming patterns and assessing impacts of climate change,” it added.

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Population growth

Furthermore, the expansion of all tropical regions and contraction of all temperate and alpine regions in Kenya may serve on a smaller scale as a microcosm to understanding the expansion of the global tropics, which the scientific community has struggled to characterise.

“Similar observations of decreased rains, warming temperatures coupled with rapid population growth under a warmer climate have been observed in neighbouring Uganda signalling a major regional to global challenge,” they also noted.

Kenya is one of the countries experiencing population explosion. Half of its population is aged 25 years and below. PHOTO | FILE | NMG

The expansion of global drylands under climate change is particularly concerning. Global drylands cover about 41 percent of the Earth’s land surface, have expanded over the latter half of the 20th century, and are projected to expand 10–15 percent during the 21st century. Africa has one of the most extensive dryland systems, which comprises roughly 15 percent of the global land area under desert.

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Climate adaptation strategies

The scientists urge the need for climate adaptation strategies in Kenya.

“With a better understanding of how climate shifts occurred in an environment like Kenya, we can estimate how food security will be impacted in other regions with similar geographic patterns,” said Prof Enbal Shacham, professor of behavioural science and health education at Saint Louis University’s College for Public Health and Social Justice and acting director of strategic initiatives for the Taylor Geospatial Institute.

The research published in Regional Environmental Change, focused on Kenya because rain-fed agriculture is central to the country’s economy and key food-producing country for the region.

It also said the findings highlight the urgent need for adaptation strategies that take into account the impacts of shifting climate zones on food security.

They underscore the need to develop land use and ecosystem management practices that can help mitigate the impact of climate change and maintain ecological diversity.

“Information on climate change and shifting climate zones in this paper can better inform the Kenyan National Climate Change Response Strategy and be used to investigate a variety of ecological questions and aid in the effort to reach the UN Sustainable Development Goals.”

Data showed that in addition to the 1°C increase in temperature, there was a decrease in precipitation during the long rains (March to May) and an increase in precipitation in the short rain season (November and December).

A woman fetches water from a water pan in Kenya. PHOTO | FILE | NMG

“An area 76,346km2 shifted from cooler to hotter zones, while 1,298km2 shifted from hotter to cooler zones. Human-induced climate change significantly alters the spatial-temporal patterns of climate zones, driving agricultural land use and ecosystem change. Changes to the climate zone alter the biological and physical properties of the ecosystem, leading to a change in what an ecosystem can support,” say the scientists.

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Data reviewed

The researchers reviewed data from among others average monthly and annual temperature and precipitation trends and time series of Kenya between 1975 and 2020, obtained from the Climate Change Knowledge Portal, Georeferenced average monthly temperature and precipitation across Kenya with a 5-kilometer resolution during 1976-1980, 1996-2000 and 2016-2020 from the TerraClimate dataset and a digitized version of the georeferenced boundaries of the Kenyan ACZs documented in 1982 and obtained through the Igad Climate Prediction and Application Centre Portal.

“Human-induced climate change in Kenya resembles global trends,” the research found, “with certain regions being more sensitive to the forces of climate change.”

“The detectability of shifting climate zones and the rate and time of the changes has yet to be adequately addressed at the regional-to-local scale,” say the scientists.

This work was supported in part by the Taylor Geospatial Institute, the Living Earth Collaborative at Washington University in St. Louis, the UK Biotechnology and Biological Sciences Research Council, the Department for International Development, the Economic & Social Research Council, the Medical Research Council, the Natural Environment Research Council, and the Defence Science & Technology Laboratory, under the Zoonoses and Emerging Livestock Systems (ZELS) programme, and the CGIAR One Health initiative “Protecting Human Health Through a One Health Approach,” which was supported by contributors to the CGIAR Trust Fund.