Dr. Joyce Kimutai is a climate scientist with the World Weather Attribution Consortium at Imperial College London’s Centre for Environmental Policy and the Kenya Meteorological Service Authority, and is a board member of HERA’s Heat Science Hotline.
As record-breaking heat pushes communities beyond the limits of what they’ve experienced before, Dr. Joyce Kimutai is helping answer a critical question: how much of today’s extreme weather is due to climate change? Her work does not simply explain the past, it helps policymakers prepare for a more dangerous future, as the climate continues to warm.
As a climate attribution scientist, Kimutai investigates how much climate change has altered the likelihood and severity of extreme weather events. Attribution science has become one of the most important tools for helping governments understand not only whether climate change is occurring, but how it is affecting people’s lives and livelihoods. “We’ve had heatwave events before, but are we now seeing them become more frequent or more intense? What is the role of climate change in that? This kind of science helps us understand whether we’re experiencing more impacts from heatwaves — for example, more people dying because we’re having more record-breaking, more frequent events.”
For Kimutai, the science is only the first step. The data needs to be translated into action. “If we say London is now experiencing 40 °C heat that wasn’t the norm, and that we’ll see it every two or three years, policymakers need to comprehend what that means in practice — what they need to do to protect communities, women, people with disabilities, people with chronic illnesses. We can explain the numbers, but translating them into action takes more than climate science alone. There is value in interdisciplinary expertise making climate information meaningful for decision-makers.”
The Burning Question: What should practitioners/researchers be asking that they aren’t?
The question of what “extreme heat” means in an African context — rather than importing definitions from elsewhere that don’t fit — is a significant issue, and part of what drew Dr. Kimutai to focus on extreme heat in Africa.
“We’ve been using thresholds that don’t work for the African context. And it goes deeper than that — we haven’t been reporting and documenting heatwaves well. There’s a misconception that Africa is ‘naturally hot,’ without understanding that any slight variation in temperature can be very detrimental to physiological functioning and health. People who live somewhere with almost constant temperatures year-round, like much of Africa, are more vulnerable to fluctuations, which are now becoming bigger due to climate change.
“The core issue, though, is that heatwaves go under-recorded in Africa, so their impacts are severely underreported. Met offices issue daily temperature forecasts but haven’t prioritized defining heatwaves by developing thresholds or explaining what it really means to exceed, say, 32°C in Nairobi for three consecutive days — who does that impact—so they don’t issue heat warnings at all. They’ll just give a typical temperature forecast without explaining what that means.
Kenya alone is incredibly diverse: Mombasa on the coast and Kisumu on the shores of Lake Victoria are low-lying and humid; Nairobi is on a plateau and can be quite cold because of elevation. Garissa is hot and dry. There are entirely different climate regimes within one country, but it isn’t being thought through — not from the physical side, and not from the impact or health-system-preparedness side.
A study she conducted two years ago found that Mombasa has informal guidelines around adjusting work hours — starting earlier, pausing during peak heat, resuming later — but these were not standardized or applied across all employers. “There’s no consistent framework to protect people, whether they live in informal settlements or work as outdoor or indoorn laborers. So I felt it was important to develop thresholds that actually speak to the needs of communities across different African contexts.”
With El Niño years bringing their own heat extremes on top of long-term warming trends, it’s important to consider how that layering compounds risk. Kimutai explains that while scientists continue to study how climate change affects El Niño itself, there is no uncertainty that every El Niño event is now unfolding in a much hotter world.
“Whatever regional effects El Niño brings — drought in one place, floods or extreme heat in another — those effects are layered on top of accelerated warming. We saw this in 2023, when we hit around 1.45°C above pre-industrial levels, and we may go higher. What that means is that extremes will be intensified — whatever extreme happens in a region, expect it to be more severe. So for policymakers and decision-makers responsible for protecting communities, the priority is figuring out how to help communities anticipate these risks better.”
The Surprise: What have you learned in your own work that challenged your assumptions?
One of the things that has surprised Dr. Kimutai most in her work is “how conservative we’ve been as scientists. It’s inherent in our training. We’ve been told: just write your reports, don’t be an alarmist or an advocate, or it undermines your credibility. What we’re seeing now is something we’ve actually seen coming for a while. That’s part of why more scientists are becoming vocal and concerned, and why there’s pushback asking, ‘why are you talking about this so much — why aren’t you being a “proper” scientist?'”
A layer of difficulty in communicating the severity of climate change comes from limitations in data and modeling, which have led to underestimating the threat.
“When we evaluated other models against observed trends, we found consistent underestimation. This connects to what I said about scientists being conservative — but it’s also partly about the tools. It worries me for the African continent specifically, because there hasn’t been enough research to understand regional dynamics well enough to fine-tune the models for that context. So the analysis and information we provide for policy may actually be underestimating the scale of the problem.
“At the same time, we shouldn’t treat a lack of models or data as a dead end. Climate change isn’t just a physical-science problem; it’s a whole-system problem. Participatory methods — working directly with communities to understand impacts — matter just as much as data density. I keep coming back to: what data sources and information are genuinely useful for the African continent to respond to this crisis in ways that work for African contexts — African solutions for African problems.”
The Underrated Fix: What’s a solution that deserves more attention than it gets?
“Using locally available materials and resources. I don’t know if this is a colonial legacy, but I see a tendency in Africa to import materials rather than use what’s local. People have lived in these regions for generations and know how to keep a house cool using what’s available — our ancestors did this. Old building styles — mud houses, for instance — that some people now see as backward were actually beautifully adapted to the local climate. Those rooms stayed cool, just through design and local materials. You still see this in West Africa.
My advice to anyone providing climate solutions: you don’t need to import something— if you ask a community to wait on materials shipped from China, they’ll be dead before they arrive. Using local resources is low-cost, and it supports communities directly.”
What is a question you want to be asked?
“Is a heatwave a problem in Africa? It sounds simple, but I’d love to answer it. It might seem like a basic question to some of us, but there are real misconceptions around it that need addressing. Climate is changing everywhere. We do experience heatwaves here — just because they haven’t been documented or written about doesn’t mean they aren’t killing and impacting people. They are.”
For Kimutai, changing that perception is more than a communications challenge—it’s a public health imperative. Until African heatwaves are measured, understood, and treated as the deadly hazards they are, millions of people will remain exposed to a crisis that is too often invisible.