Heavy Rainfall That Led To Deadly Floods Are Becoming Common Due To Climate Change

The heavy rainfall that led to deadly floods and killed 9 people in Botswana and 22 in South Africa in February 2025 is becoming more common, according to a new rapid study by World Weather Attribution. The study suggests climate change is the most likely cause, and highlights that rapid urbanisation and a limited drainage infrastructure contributed to turning the extreme rainfall event into a deadly.

The heavy rainfall that led to deadly floods and killed 9 people in Botswana and 22 in South Africa in February 2025 is becoming more common, according to a new rapid study by World Weather Attribution. The study suggests climate change is the most likely cause, and highlights that rapid urbanisation and a limited drainage infrastructure contributed to turning the extreme rainfall event into a human disaster.

Some of the findings of the study include:

Extreme rainfall is becoming more intense in the region. Historical weather observations show an increasing trend in 5-day rainfall over the last few decades. Using only these observations, the researchers estimate that similar rainfall events are today about 60% more intense than they were in pre-industrial times, before humans started burning fossil fuels.

The researchers could not quantify the precise contribution of climate change to the event. Climate models do not show a consistent change in rainfall, as seen in the observations, they explain. Because of this, the exact numbers have high mathematical uncertainty.

But when climate models are used to look at the future and what will happen in the region with further warming, the majority of the models show an increase in extreme rainfall. The scientists explain that as the planet warms more, the effect of climate change in the rainfall becomes clearer.

The impacts of the heavy rainfall were made worse by a combination of inadequate infrastructure, rapid urbanization, and insufficient drainage capacity. In Gaborone and other places, infrastructure development has not kept pace with growing population and rapid urbanisation, leaving critical systems vulnerable. But the researchers note that improvements are already underway in some cities and will help reduce future flood risk if completed.

Dr Ben Clarke, Researcher at the Centre for Environmental Policy, Imperial College London, said: “Human-caused climate change seems to have played a role in these tragic floods. Weather data indicates that heavy rainfall has become more intense in the last decades in southern Botswana, and climate models show that the situation will become even more dangerous in the future. This is exactly what we expect from physics, as a warmer atmosphere can hold more moisture and lead to more extreme downpours. To limit the damage we need to cut fossil fuel emissions and adapt to a warmer climate”.

Between 16-20 February, southern Botswana and eastern South Africa were hit by five consecutive days of heavy rainfall that caused severe flooding across the region. At least 31 people died, including six children, and about 5,000 people were displaced.

Scientists from World Weather Attribution used satellite data, weather observations and climate models to evaluate the role of climate change in the five-day rainfall event that led to the floods. The team also looked at the conditions that turned the event into a humanitarian disaster. Although the team could not quantify the role of climate change, the researchers concluded that global warming played a role in the floods. They base their conclusion on three lines of evidence.

First, datasets of weather observations show a very strong trend towards more intense rainfall in the region. Second, although climate models show different rainfall trends in the current climate, most models shift towards an increased trend in rainfall when looking at the future. Scientists interpret this change as an emergence of the climate change signal, which will become more evident with further warming. Finally, the increase in rainfall is consistent with the physical science and the fact that warmer air can hold more water vapour, leading to more intense rains.

The researchers also highlight that the impacts were likely magnified by infrastructure not built to withstand such extreme rainfall. And they note that urban drainage improvements underway will help cities in Botswana better cope with the growing risks from climate change.

The study was conducted by 15 researchers as part of the World Weather Attribution group, including scientists from universities and meteorological agencies in Botswana, Denmark, Mexico, the Netherlands, South Africa, Sweden, the United Kingdom and the United States.

Scientists globally agree that climate change, caused by burning oil, coal and gas and deforestation, is making rainfall heavier in many regions of the world. To quantify the effect of human-caused warming on the heavy downpours that caused floods in Botswana, researchers analysed weather data and climate models using peer-reviewed methods to compare how these types of events have changed between today’s climate.

Professor Piet Kenabatho, Department of Environmental Science, University of Botswana said: “In the last 10 years, Botswana experienced at least three years of extreme rainfall events, in 2017, 2021 and 2025, all happening in the month of February, almost around the same period – 15.-20 February. “In particular, the 2017 and 2025 events led to severe floods, mainly in the City of Gaborone, where most properties were flooded, roads closed, and unfortunately with some lives lost due to drowning in some places across Botswana. On a positive note, one of the difficult-to-fill dams in Botswana-Gaborone dam which is located in the city of Gaborone was filled to capacity during the two rainfall events.

“Our study adds to other research conducted in Botswana and southern Africa showing that these extreme events are a result of climate change due to global warming. As stated by the United Nations, countries must adapt to climate change by improving their management of water resources. Only that way we can limit the impacts of global warming and tackle poverty.”

“In light of this, and given the current state of drainage systems in Botswana and the frequency of extreme rainfall events, investment in adequate storm water management systems is more
than urgent if Botswana is to cope with the effects of climate change.”

Mr Tiro Nkemelang, Researcher at the Botswana Institute for Technology Research and Innovation, and PhD candidate at the African Climate and Development Initiative of the University of Cape Town said: “Climate change is real and undeniably affecting us. The recent floods serve as clear evidence of its impact, which we are already experiencing. Our study suggests that similar extreme rainfall events and their associated impacts may increase in the future, highlighting the need for proactive measures to enhance resilience.

“Notably, this rapid attribution study comes at a time when the impact of climate change on extreme weather events in Botswana—and its broader implications for the nation—remains largely understudied. While this research helps bridge that gap, it also underscores the need for greater investment in local weather and climate research, particularly at the intersection of climate and development.’”

The writer of this article is Dr. Seema Javed, an environmentalist & a communications professional in the field of climate and energy