UNEP Sounds Alarm on Floods and Toxic Pollution in Kenya

The recurring devastating floods in the country are unearthing buried heavy metals like lead and cadmium from colonial-era industrial sediments, a new United Nations Environment Programme (UNEP) report informs.

The Frontiers 2025 report, titled “The Weight of Time: Facing a New Age of Challenges for People and Ecosystems,” also shows that receding glaciers on Mount Kenya are threatening water supplies, declining river levels due to ageing barriers are disrupting ecosystems, and the nation’s growing elderly population faces heightened dangers from heatwaves and pollution.

The UNEP report highlights these interconnected threats, urging immediate action to safeguard Kenya’s vulnerable communities.

The report, UNEP’s seventh in the Frontiers series, identifies four emerging environmental issues with profound implications for Kenya, a nation already grappling with climate change despite contributing minimally to global emissions.

^{Flooding Kenya in the past has caused havoc | Photo Courtesy}

Inger Andersen, UNEP’s Executive Director, emphasized the urgency: “We must be prepared for the risks these impacts pose, especially for society’s most vulnerable.”

For Kenya, these warnings are not hypothetical as recent events, including the 2024 floods that displaced thousands in Nairobi and along the Athi River, illustrate the report’s dire predictions.

Central to the report’s concerns is the remobilization of legacy pollutants by intensifying flood events, a phenomenon hitting Kenya’s urban and rural areas hard.

Floods, projected to cause up to 20 times more damage by 2100 without adaptation measures, are disturbing sediments laden with toxic heavy metals and persistent organic pollutants (POPs) from decades-old mining, agriculture, and industrial activities.

In Nairobi, rivers like the Ngong and Mathare, flowing through densely populated slums, have shown alarming levels of arsenic, cadmium, lead, mercury, and PCBs, remobilized during floods in 2012, 2016, 2018, and 2024.

These contaminants bioaccumulate in fish and crops, leading to health risks such as cancers, kidney damage, and neurological disorders, particularly affecting low-income communities reliant on these water sources.

The report warns that without monitoring and flood defenses, such as wetland restoration, these “forgotten but not gone” toxins could cascade into widespread public health crises across Kenya’s flood-prone regions, including the Tana River Delta and Lake Victoria basin.

Compounding this is the rapid recession of Kenya’s glaciers, detailed in the report’s chapter on the warming cryosphere. Mount Kenya’s glaciers, a vital water towers for rivers feeding millions, have lost over 80% of their mass in recent decades, with projections of near-total disappearance by 2030.

This thaw not only diminishes water availability, exacerbating droughts in arid and semi-arid lands (ASALs) that cover 80% of Kenya, but also risks awakening “zombie microbes” dormant in the ice for millennia.

Potential pathogen releases could strain Kenya’s health infrastructure that is already burdened by diseases like malaria and cholera.

The implications extend to agriculture as reduced glacial meltwater threatens irrigation for tea and coffee farms in the central highlands, potentially slashing yields and impacting the economy, which relies on agriculture for 25% of GDP.

^{Reported floods in 2024 that submerged schools and villages in various parts in the country | Photo Courtesy}

Declining river levels, driven by ageing dams and barriers, form another critical warning in the report. Kenya’s rivers, including the Ewaso Ng’iro and Athi, are increasingly fragmented by colonial-era weirs and modern hydropower structures, impeding 89% of global river volumes and disrupting fish migration, sediment flow, and biodiversity.

In Laikipia and Samburu counties, these barriers have led to lower water levels downstream, fueling conflicts between pastoralists and wildlife, and worsening food insecurity.

The report advocates for barrier removal, citing successful European examples, to restore connectivity and enhance resilience against floods and droughts. For Kenya, this could mean dismantling obsolete dams to revive ecosystems, but experts caution that political and economic ties to hydropower may hinder progress.

Amid these environmental shifts, Kenya’s ageing population, expected to double by 2050, is emerging as particularly vulnerable. The report notes that heat-related deaths among those over 65 have risen 85% globally since the 1990s, a trend amplified in Kenya’s urban heat islands like Nairobi’s informal settlements.

Elderly residents, often living in flood-prone or polluted areas, face compounded risks from extreme weather, air pollution, and disasters. In the 2023 heatwave, hundreds of older Kenyans suffered respiratory issues exacerbated by wildfire smoke and urban smog.

The document calls for age-friendly policies, such as green spaces and early warning systems, to protect this demographic, which constitutes 5% of Kenya’s population but bears disproportionate health burdens.

Environmental experts in Kenya are echoing the report’s call for integrated solutions. Dr. Jane Mutua, a Nairobi-based climate researcher, told reporters: “These issues are interconnected. Floods release pollutants that harm the elderly, while receding glaciers dry up rivers essential for all. Kenya must prioritize nature-based adaptations like reforestation and sustainable urban planning.”

Government officials have acknowledged the findings, with the Ministry of Environment pledging to incorporate them into the National Climate Change Action Plan, though funding gaps remain a challenge.