The historic drought in the Horn of Africa, which left an estimated 4.3 million people in immediate need of humanitarian aid and an estimated 43,000 dead last year in Somalia, would not have happened without climate change, according to published scientific research today.

“Climate change due to human activities has made droughts in the Horn of Africa about 100 times more likely,” said the World Weather Attribution (WWA), a global network of scientists researching the link between climate extremes and climate deregulation.

As of late 2020 countries in the Horn of Africa—Ethiopia, Eritrea, Somalia, Djibouti, Kenya and Sudan—are facing their worst drought in 40 years.

After five rainy seasons without significant rainfall, crops were destroyed and millions of livestock died. According to the UN, 22 million people are at risk of starvation in Ethiopia, Kenya and Somalia.

As the 19 scientists who wrote the research pointed out, climate change had “small effects on annual rainfall” in the region. But it significantly affected the increase in temperature, which is responsible for the steep rise in evapotranspiration that led to record drying of soils and plants.

“Climate change has caused this severe and unprecedented drought,” said Joyce Kimutai, a Kenyan climatologist with the Kenya Meteorological Service who participated in the research. She and her team concluded that if the temperature had been 1.2 degrees Celsius lower, the combination of reduced rainfall and evapotranspiration “would not have led to the drought”.